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Sample records for suppressing advanced glycation

  1. Reactive immunization suppresses advanced glycation and mitigates diabetic nephropathy.

    PubMed

    Shcheglova, Tatiana; Makker, Sudesh; Tramontano, Alfonso

    2009-05-01

    Agents that inhibit glycation end products by reducing the carbonyl load from glycation and glycoxidation are an emerging pharmacologic approach to treat complications of diabetes. We previously demonstrated that antibodies generated to the glycoprotein keyhole limpet hemocyanin (KLH) can cross-link with reactive carbonyl residues on protein conjugates. Here, we immunized streptozotocin-induced diabetic rats with KLH to assess the capacity of the elicited antibodies to intercept carbonyl residues on glycated proteins and to mitigate glycation-related pathology. Compared with diabetic rats immunized with adjuvant alone, KLH-immunized diabetic rats had decreased levels of glycated peptides in sera and demonstrated a reduction in albuminuria, proteinuria, deposition of glycation end products in the kidney, and histologic damage. In vitro, low molecular weight glycated peptides from rat serum reacted with anti-KLH antibodies at a faster rate than normal IgG and selectively modified the lambda chains. The reaction products contained peptide sequences from type I collagen alpha chain, albumin, and LDL receptor-related protein. These adduction reactions were inhibited by free KLH and by reduction of glycated peptides with borohydride. In summary, these results suggest that inherent reactivity of Ig light chains provides a natural mechanism for the removal of cytotoxic glycation products. This reactivity can be augmented by glycoprotein-specific reactive immunization, a potential biopharmaceutical approach to glycation-related pathology.

  2. Receptor for advanced glycation end products inhibits proliferation in osteoblast through suppression of Wnt, PI3K and ERK signaling

    SciTech Connect

    Li, Guofeng; Xu, Jingren; Li, Zengchun

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer RAGE overexpression suppresses cell proliferation in MC3T3-E1 cells. Black-Right-Pointing-Pointer RAGE overexpression decreases Wnt/{beta}-catenin signaling. Black-Right-Pointing-Pointer RAGE overexpression decreases ERK and PI3K signaling. Black-Right-Pointing-Pointer Inhibition of Wnt signaling abolishes PI3K signaling restored by RAGE blockade. Black-Right-Pointing-Pointer Inhibition of Wnt signaling abolishes ERK signaling restored by RAGE blockade. -- Abstract: Expression of receptor for advanced glycation end products (RAGE) plays a crucial role in bone metabolism. However, the role of RAGE in the control of osteoblast proliferation is not yet evaluated. In the present study, we demonstrate that RAGE overexpression inhibits osteoblast proliferation in vitro. The negative regulation of RAGE on cell proliferation results from suppression of Wnt, PI3K and ERK signaling, and is restored by RAGE neutralizing antibody. Prevention of Wnt signaling using Sfrp1 or DKK1 rescues RAGE-decreased PI3K and ERK signaling and cell proliferation, indicating that the altered cell growth in RAGE overexpressing cells is in part secondary to alterations in Wnt signaling. Consistently, RAGE overexpression inhibits the expression of Wnt targets cyclin D1 and c-myc, which is partially reversed by RAGE blockade. Overall, these results suggest that RAGE inhibits osteoblast proliferation via suppression of Wnt, PI3K and ERK signaling, which provides novel mechanisms by which RAGE regulates osteoblast growth.

  3. Advanced glycation end products

    PubMed Central

    Gkogkolou, Paraskevi; Böhm, Markus

    2012-01-01

    Aging is the progressive accumulation of damage to an organism over time leading to disease and death. Aging research has been very intensive in the last years aiming at characterizing the pathophysiology of aging and finding possibilities to fight age-related diseases. Various theories of aging have been proposed. In the last years advanced glycation end products (AGEs) have received particular attention in this context. AGEs are formed in high amounts in diabetes but also in the physiological organism during aging. They have been etiologically implicated in numerous diabetes- and age-related diseases. Strategies inhibiting AGE accumulation and signaling seem to possess a therapeutic potential in these pathologies. However, still little is known on the precise role of AGEs during skin aging. In this review the existing literature on AGEs and skin aging will be reviewed. In addition, existing and potential anti-AGE strategies that may be beneficial on skin aging will be discussed. PMID:23467327

  4. Linagliptin blocks renal damage in type 1 diabetic rats by suppressing advanced glycation end products-receptor axis.

    PubMed

    Nakashima, S; Matsui, T; Takeuchi, M; Yamagishi, S-I

    2014-09-01

    Advanced glycation end products (AGEs) and their receptor (RAGE) play a role in diabetic nephropathy. We have recently found that linagliptin, an inhibitor of dipeptidyl peptidase-4 (DPP-4) suppresses the AGE-induced oxidative stress generation and intercellular adhesion molecule-1 (ICAM-1) gene expression in endothelial cells. However, whether linagliptin could have beneficial effects on experimental diabetic nephropathy in a glucose-lowering independent manner remains unknown. To address the issue, this study examined the effects of linagliptin on renal damage in streptozotocin-induced diabetic rats. Serum levels of DPP-4 were significantly elevated in diabetic rats compared with control rats. Although linagliptin treatment for 2 weeks did not improve hyperglycemia in diabetic rats, linagliptin significantly reduced AGEs levels, RAGE gene expression, and 8-hydroxy-2'-deoxyguanosine, a marker of oxidative stress in the kidney of diabetic rats. Furthermore, linagliptin significantly reduced albuminuria, renal ICAM-1 mRNA levels, and lymphocyte infiltration into the glomeruli of diabetic rats. Our present study suggests that linagliptin could exert beneficial effects on diabetic nephropathy partly by blocking the AGE-RAGE-evoked oxidative stress generation in the kidney of streptozotocin-induced diabetic rats. Inhibition of DPP-4 by linagliptin might be a promising strategy for the treatment of diabetic nephropathy.

  5. Scopoletin protects against methylglyoxal-induced hyperglycemia and insulin resistance mediated by suppression of advanced glycation endproducts (AGEs) generation and anti-glycation.

    PubMed

    Chang, Wen-Chang; Wu, Shinn-Chih; Xu, Kun-Di; Liao, Bo-Chieh; Wu, Jia-Feng; Cheng, An-Sheng

    2015-02-09

    Recently, several types of foods and drinks, including coffee, cream, and cake, have been found to result in high methylglyoxal (MG) levels in the plasma, thus causing both nutritional and health concerns. MG can be metabolized by phase-II enzymes in liver through the positive regulation of nuclear factor-erythroid 2-related factor 2 (Nrf2). In this study, we investigated the ability of scopoletin (SP) to protect against MG-induced hyperglycemia and insulin resistance. Recently, SP was shown to be a peroxisome proliferator-activated receptor-γ activator to elevate insulin sensitivity. We investigated the effects of oral administration of SP on the metabolic, biochemical, and molecular abnormalities characteristic of type 2 diabetes in MG-treated Wistar rats to understand the potential mechanism of scopoletin for diabetes protection. Our results suggested that SP activated Nrf2 by Ser40 phosphorylation, resulting in the metabolism of MG into d-lactic acid and the inhibition of AGEs generation, which reduced the accumulation of AGEs in the livers of MG-induced rats. In this manner, SP improved the results of the oral glucose tolerance test and dyslipidemia. Moreover, SP also increased the plasma translocation of glucose transporter-2 and promoted Akt phosphorylation caused by insulin treatment in MG-treated FL83B hepatocytes. In contrast, SP effectively suppressed protein tyrosine phosphatase 1B (PTP1B) expression, thereby alleviating insulin resistance. These findings suggest that SP acts as an anti-glycation and anti-diabetic agent, and thus has therapeutic potential for the prevention of diabetes.

  6. Metformin Inhibits Advanced Glycation End Products-Induced Inflammatory Response in Murine Macrophages Partly through AMPK Activation and RAGE/NFκB Pathway Suppression

    PubMed Central

    Zhou, Zhong'e; Tang, Yong; Chen, Chengjun; Lu, Yi; Liu, Liang

    2016-01-01

    Advanced glycation end products (AGEs) are major inflammatory mediators in diabetes, affecting atherosclerosis progression via macrophages. Metformin slows diabetic atherosclerosis progression through mechanisms that remain to be fully elucidated. The present study of murine bone marrow derived macrophages showed that (1) AGEs enhanced proinflammatory cytokines (interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α)) mRNA expression, RAGE expression, and NFκB activation; (2) metformin pretreatment inhibited AGEs effects and AGEs-induced cluster designation 86 (CD86) (M1 marker) expression, while promoting CD206 (M2 marker) surface expression and anti-inflammatory cytokine (IL-10) mRNA expression; and (3) the AMPK inhibitor, Compound C, attenuated metformin effects. In conclusion, metformin inhibits AGEs-induced inflammatory response in murine macrophages partly through AMPK activation and RAGE/NFκB pathway suppression. PMID:27761470

  7. Metformin Inhibits Advanced Glycation End Products-Induced Inflammatory Response in Murine Macrophages Partly through AMPK Activation and RAGE/NFκB Pathway Suppression.

    PubMed

    Zhou, Zhong'e; Tang, Yong; Jin, Xian; Chen, Chengjun; Lu, Yi; Liu, Liang; Shen, Chengxing

    2016-01-01

    Advanced glycation end products (AGEs) are major inflammatory mediators in diabetes, affecting atherosclerosis progression via macrophages. Metformin slows diabetic atherosclerosis progression through mechanisms that remain to be fully elucidated. The present study of murine bone marrow derived macrophages showed that (1) AGEs enhanced proinflammatory cytokines (interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α)) mRNA expression, RAGE expression, and NFκB activation; (2) metformin pretreatment inhibited AGEs effects and AGEs-induced cluster designation 86 (CD86) (M1 marker) expression, while promoting CD206 (M2 marker) surface expression and anti-inflammatory cytokine (IL-10) mRNA expression; and (3) the AMPK inhibitor, Compound C, attenuated metformin effects. In conclusion, metformin inhibits AGEs-induced inflammatory response in murine macrophages partly through AMPK activation and RAGE/NFκB pathway suppression.

  8. DNA aptamer raised against advanced glycation end products (AGEs) improves glycemic control and decreases adipocyte size in fructose-fed rats by suppressing AGE-RAGE axis.

    PubMed

    Ojima, A; Matsui, T; Nakamura, N; Higashimoto, Y; Ueda, S; Fukami, K; Okuda, S; Yamagishi, S

    2015-04-01

    Advanced glycation end products (AGEs) decrease adiponectin expression and suppress insulin signaling in cultured adipocytes through the interaction with a receptor for AGEs (RAGE) via oxidative stress generation. We have recently found that high-affinity DNA aptamer directed against AGE (AGE-aptamer) prevents the progression of experimental diabetic nephropathy by blocking the harmful actions of AGEs in the kidney. This study examined the effects of AGE-aptamer on adipocyte remodeling, AGE-RAGE-oxidative stress axis, and adiponectin expression in fructose-fed rats. Although AGE-aptamer treatment by an osmotic mini pump for 8 weeks did not affect serum insulin levels, it significantly decreased average fasting blood glucose and had a tendency to inhibit body weight gain in fructose-fed rats. Furthermore, AGE-aptamer significantly suppressed the increase in adipocyte size and prevented the elevation in AGEs, RAGE, and an oxidative stress marker, 8-hydroxydeoxyguanosine (8-OHdG), levels in adipose tissues of fructose-fed rats at 14-week-old, while it restored the decrease in adiponectin mRNA levels. Our present study suggests that AGE-aptamer could improve glycemic control and prevent adipocyte remodeling in fructose-fed rats partly by suppressing the AGE-RAGE-mediated oxidative stress generation. AGE-aptamer might be a novel therapeutic strategy for fructose-induced metabolic derangements.

  9. Metformin inhibits advanced glycation end products (AGEs)-induced renal tubular cell injury by suppressing reactive oxygen species generation via reducing receptor for AGEs (RAGE) expression.

    PubMed

    Ishibashi, Y; Matsui, T; Takeuchi, M; Yamagishi, S

    2012-11-01

    Advanced glycation end products (AGEs) and their receptor (RAGE) play a role in tubulointerstitial damage in diabetic nephropathy. Recently, metformin has been shown to ameliorate tubular injury both in cell culture and diabetic animal model. However, effects of metformin on AGEs-induced tubular cell apoptosis and damage remain unknown. We examined here whether and how metformin could block the AGEs-RAGE-elicited tubular cell injury in vitro. Gene expression level was evaluated by real-time reverse-transcription polymerase chain reactions. Reactive oxygen species (ROS) generation was measured with dihydroethidium staining. Apoptosis was evaluated by DNA fragmentation and annexin V expression level. AGEs upregulated RAGE mRNA levels and subsequently increased ROS generation and intercellular adhesion molecule-1, monocyte chemoattractant protein-1 and transforming growth factor-β gene expression in human renal proximal tubular cells, all of which were significantly blocked by the treatment of 0.01 and 0.1 mM metformin. Compound C, an inhibitor of AMP-activated protein kinase significantly blocked the effects of metformin on RAGE gene expression and ROS generation in AGEs-exposed tubular cells. Furthermore, metformin dose-dependently inhibited the AGEs-induced apoptotic cell death of tubular cells; 1 mM metformin completely suppressed the pro-apoptotic effects of AGEs in 2 different assay systems. Our present study suggests that metformin could inhibit the AGEs-induced apoptosis and inflammatory and fibrotic reactions in tubular cells probably by reducing ROS generation via suppression of RAGE expression through AMP-activated protein kinase activation. Metformin may protect against tubular cell injury in diabetic nephropathy by blocking the AGEs-RAGE-ROS axis.

  10. Fibroblast growth factor 21 protects mouse brain against D-galactose induced aging via suppression of oxidative stress response and advanced glycation end products formation.

    PubMed

    Yu, Yinhang; Bai, Fuliang; Wang, Wenfei; Liu, Yaonan; Yuan, Qingyan; Qu, Susu; Zhang, Tong; Tian, Guiyou; Li, Siming; Li, Deshan; Ren, Guiping

    2015-06-01

    Fibroblast growth factor 21 (FGF21) is a hormone secreted predominantly in the liver, pancreas and adipose tissue. Recently, it has been reported that FGF21-Transgenic mice can extend their lifespan compared with wild type counterparts. Thus, we hypothesize that FGF21 may play some roles in aging of organisms. In this study d-galactose (d-gal)-induced aging mice were used to study the mechanism that FGF21 protects mice from aging. The three-month-old Kunming mice were subcutaneously injected with d-gal (180mg·kg(-1)·d(-1)) for 8weeks and administered simultaneously with FGF21 (1, 2 or 5mg·kg(-1)·d(-1)). Our results showed that administration of FGF21 significantly improved behavioral performance of d-gal-treated mice in water maze task and step-down test, reduced brain cell damage in the hippocampus, and attenuated the d-gal-induced production of MDA, ROS and advanced glycation end products (AGEs). At the same time, FGF21 also markedly renewed the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and total anti-oxidation capability (T-AOC), and decreased the enhanced total cholinesterase (TChE) activity in the brain of d-gal-treated mice. The expression of aldose reductase (AR), sorbitol dehydrogenase (SDH) and member-anchored receptor for AGEs (RAGE) declined significantly after FGF21 treatment. Furthermore, FGF21 suppressed inflamm-aging by inhibiting IκBα degradation and NF-κB p65 nuclear translocation. The expression levels of pro-inflammatory cytokines, such as TNF-α and IL-6, decreased significantly. In conclusion, these results suggest that FGF21 protects the aging mice brain from d-gal-induced injury by attenuating oxidative stress damage and decreasing AGE formation.

  11. Advanced Glycation End Products and Diabetic Complications

    PubMed Central

    Singh, Varun Parkash; Bali, Anjana; Singh, Nirmal

    2014-01-01

    During long standing hyperglycaemic state in diabetes mellitus, glucose forms covalent adducts with the plasma proteins through a non-enzymatic process known as glycation. Protein glycation and formation of advanced glycation end products (AGEs) play an important role in the pathogenesis of diabetic complications like retinopathy, nephropathy, neuropathy, cardiomyopathy along with some other diseases such as rheumatoid arthritis, osteoporosis and aging. Glycation of proteins interferes with their normal functions by disrupting molecular conformation, altering enzymatic activity, and interfering with receptor functioning. AGEs form intra- and extracellular cross linking not only with proteins, but with some other endogenous key molecules including lipids and nucleic acids to contribute in the development of diabetic complications. Recent studies suggest that AGEs interact with plasma membrane localized receptors for AGEs (RAGE) to alter intracellular signaling, gene expression, release of pro-inflammatory molecules and free radicals. The present review discusses the glycation of plasma proteins such as albumin, fibrinogen, globulins and collagen to form different types of AGEs. Furthermore, the role of AGEs in the pathogenesis of diabetic complications including retinopathy, cataract, neuropathy, nephropathy and cardiomyopathy is also discussed. PMID:24634591

  12. Endogenous alpha-oxoaldehydes and formation of protein and nucleotide advanced glycation endproducts in tissue damage.

    PubMed

    Thornalley, Paul J

    2007-01-01

    Human and other biological tissues face a continual threat of damage by alpha-oxoaldehydes formed endogenously. Glyoxal, methylglyoxal and 3-deoxyglucosone are formed by the degradation of glycolytic intermediates, glycated proteins and lipid peroxidation. They are potent glycating agents of protein and nucleotides leading to the formation of advanced glycation endproducts (AGEs). With proteins, they are arginine residue-directed glycating agents forming mainly hydroimidazolones, found at 0.1-1% of total arginine residues in tissues (2-20% of proteins modified). With nucleotides, imidazopurinone- and N2-carboxyalkyl- derivatives of deoxyguanosine are formed, found at 0.1-0.8 per 10(6) nucleotides in DNA. Glycation occurs in all tissues and body fluids. Cellular proteolysis of AGE-modified proteins and DNA releases glycated amino acids and nucleosides. Glycated amino acids and nucleosides are released into plasma, undergo glomerular filtration and are excreted in urine. The damage to tissue protein and nucleotides by alpha-oxoaldehydes is suppressed by the metabolism of alpha-oxoaldehyde glycating agents by the glutathione-dependent enzyme, glyoxalase I, and aldo-keto reductases. These enzymatic activities are part of the enzymatic defence against glycation. Tissue damage by alpha-oxoaldehyde glycation is implicated in diabetic and non-diabetic vascular disease, renal failure, cirrhosis, Alzheimer's disease, arthritis and ageing.

  13. Suppression of antioxidant Nrf-2 and downstream pathway in H9c2 cells by advanced glycation end products (AGEs) via ERK phosphorylation.

    PubMed

    Ko, Shun-Yao; Chang, Shu-Shing; Lin, I-Hsuan; Chen, Hong-I

    2015-11-01

    Diabetic cardiomyopathy is related to oxidative stress and correlated with the presence of advanced glycation end products (AGEs). In a clinical setting, AGEs can be detected in patients presenting diabetic cardiomyopathy; however, the underlying mechanism has yet to be elucidated. In our previous study, AGEs increase cell hypertrophy via ERK phosphorylation in a process closely related to ROS production. Thus, we propose that AGEs regulate the antioxidant gene nuclear factor-erythroid 2-related factor (Nrf-2). In H9c2 cells treated with AGEs, the expression of Nrf-2 was reduced; however, ERK phosphorylation was shown to increase. Treatment with H2O2 was also shown to increase Nrf-2 and ERK phosphorylation. In cells pretreatment with ROS scavenger NAC, the effects of H2O2 were reduced; however, the effects of the AGEs remained largely unchanged. Conversely, when cells were pretreated with PD98059 (ERK inhibitor), the expression of Nrf-2 was recovered following treatment with AGEs. Our results suggest that AGEs inhibit Nrf-2 via the ERK pathway; however, this influence is partly associated with ROS. Our finding further indicated that AGEs possess both ROS-dependent and ROS-independent pathways, resulting in a reduction in Nrf-2. This report reveals an important mechanism underlying the regulation of diabetic cardiomyopathy progression by AGEs.

  14. Metformin inhibits advanced glycation end products (AGEs)-induced growth and VEGF expression in MCF-7 breast cancer cells by suppressing AGEs receptor expression via AMP-activated protein kinase.

    PubMed

    Ishibashi, Y; Matsui, T; Takeuchi, M; Yamagishi, S

    2013-05-01

    Metformin use has been reported to decrease breast cancer incidence and mortality in diabetic patients. We have previously shown that advanced glycation end products (AGEs) and their receptor (RAGE) interaction stimulate growth and/or migration of pancreatic cancer and melanoma cells. However, effects of metformin on AGEs-RAGE axis in breast cancers remain unknown. We examined here whether and how metformin could block the AGEs-induced growth and vascular endothelial growth factor (VEGF) expression in MCF-7 breast cancer cells. Cell proliferation was measured with an electron coupling reagent WST-1 based colorimetric assay. Gene expression level was evaluated by real-time reverse-transcription polymerase chain reactions. AGEs significantly increased cell proliferation of MCF-7 cells, which was completely prevented by the treatment with 0.01 or 0.1 mM metformin or anti-RAGE antibodies. Furthermore, metformin at 0.01 mM completely suppressed the AGEs-induced upregulation of RAGE and VEGF mRNA levels in MCF-7 cells. An inhibitor of AMP-activated protein kinase, compound C significantly blocked the growth-inhibitory and RAGE and VEGF suppressing effects of metformin in AGEs-exposed MCF-7 cells. Our present study suggests that metformin could inhibit the AGEs-induced growth and VEGF expression in MCF-7 breast cancer cells by suppressing RAGE gene expression via AMP-activated protein kinase pathway. Metformin may protect against breast cancer expansion in diabetic patients by blocking the AGEs-RAGE axis.

  15. Advanced glycation end product 3 (AGE3) suppresses the mineralization of mouse stromal ST2 cells and human mesenchymal stem cells by increasing TGF-β expression and secretion.

    PubMed

    Notsu, Masakazu; Yamaguchi, Toru; Okazaki, Kyoko; Tanaka, Ken-ichiro; Ogawa, Noriko; Kanazawa, Ippei; Sugimoto, Toshitsugu

    2014-07-01

    In diabetic patients, advanced glycation end products (AGEs) cause bone fragility because of deterioration of bone quality. We previously showed that AGEs suppressed the mineralization of mouse stromal ST2 cells. TGF-β is abundant in bone, and enhancement of its signal causes bone quality deterioration. However, whether TGF-β signaling is involved in the AGE-induced suppression of mineralization during the osteoblast lineage remains unknown. We therefore examined the roles of TGF-β in the AGE-induced suppression of mineralization of ST2 cells and human mesenchymal stem cells. AGE3 significantly (P < .001) inhibited mineralization in both cell types, whereas transfection with small interfering RNA for the receptor for AGEs (RAGEs) significantly (P < .05) recovered this process in ST2 cells. AGE3 increased (P < .001) the expression of TGF-β mRNA and protein, which was partially antagonized by transfection with RAGE small interfering RNA. Treatment with a TGF-β type I receptor kinase inhibitor, SD208, recovered AGE3-induced decreases in osterix (P < .001) and osteocalcin (P < .05) and antagonized the AGE3-induced increase in Runx2 mRNA expression in ST2 cells (P < .001). Moreover, SD208 completely and dose dependently rescued AGE3-induced suppression of mineralization in both cell types. In contrast, SD208 intensified AGE3-induced suppression of cell proliferation as well as AGE3-induced apoptosis in proliferating ST2 cells. These findings indicate that, after cells become confluent, AGE3 partially inhibits the differentiation and mineralization of osteoblastic cells by binding to RAGE and increasing TGF-β expression and secretion. They also suggest that TGF-β adversely affects bone quality not only in primary osteoporosis but also in diabetes-related bone disorder.

  16. Inhibitory effect of leonurine on the formation of advanced glycation end products.

    PubMed

    Huang, Lianqi; Yang, Xin; Peng, Anlin; Wang, Hui; Lei, Xiang; Zheng, Ling; Huang, Kun

    2015-02-01

    Long-term hyperglycemia is a typical symptom of diabetes mellitus (DM) which can cause a high level of protein glycation and lead to the formation of advanced glycation end products (AGEs). The accumulation of AGEs in turn deteriorates DM and its complications. Insulin, the only hormone that directly decreases blood sugar in vivo, is vulnerable to glycation which causes the loss of its biological activity. In this study, we used a porcine insulin (PI)-methylglyoxal (MGO) model to investigate the inhibitory effect of leonurine (LN), a natural alkaloid extracted from Herba leonuri, on AGE formation. Assays including AGE-specific fluorescence, and fructosamine level and carbonyl group content determination showed that LN can dose-dependently suppress PI glycation. A significantly decreased cross-linking level on the glycated PI was also proven by SDS-PAGE electrophoresis. A further liquid chromatography-mass spectrometry study suggested that LN may inhibit PI glycation through trapping MGO and keeping it from reacting with PI. Our results thus indicate that LN is a promising anti-glycation agent for the prevention of diabetes and its complications via inhibiting AGE formation.

  17. Advanced glycation end products and diabetic retinopathy.

    PubMed

    Milne, Ross; Brownstein, Seymour

    2013-06-01

    Retinopathy is a serious microvascular complication of diabetes and a major cause of blindness in young adults, worldwide. Early diabetic retinopathy is characterized by a loss of pericytes from retinal capillaries, the appearance of acellular capillaries and microaneurysms, and a breakdown of the blood-retinal barrier. In later stages, this can evolve into the proliferative phase in which there is neovascularization of the retina, which greatly increases the probability of vision loss. Advanced glycation end products (AGEs) which accumulate under hyperglycemic conditions are thought to play an important role in the pathogenesis of diabetic retinopathy. AGEs arise primarily by the modification of amine groups of proteins by reactive dicarbonyls such as methylglyoxal. Intracellular proteins including anti-oxidant enzymes, transcription factors and mitochondrial proteins are targets of dicarbonyl modification and this can modify their functional properties and thus compromise cellular physiology. Likewise, modification of extracellular proteins by dicarbonyls can impair cell adhesion and can generate ligands that can potentially bind to cell surface AGE receptors that activate pro-inflammatory signaling pathways. AGE inhibitors have been shown to provide protection in animal models of diabetic retinopathy and currently are being evaluated in clinical trials.

  18. Autofluorescence characterization of advanced glycation end products of hemoglobin

    NASA Astrophysics Data System (ADS)

    Vigneshwaran, Nadanathangam; Bijukumar, Gopalakrishnapillai; Karmakar, Nivedita; Anand, Sneh; Misra, Anoop

    2005-01-01

    This article describes the analysis of autofluorescence of advanced glycation end products of hemoglobin (Hb-AGE). Formed as a result of slow, spontaneous and non-enzymatic glycation reactions, Hb-AGE possesses a characteristic autofluorescence at 308/345 nm ( λex/ λem). Even in the presence of heme as a quenching molecule, the surface presence of the glycated adduct gave rise to autofluorescence with the quantum yield of 0.19. The specificity of monoclonal antibody developed against common AGE structure with Hb-AGE was demonstrated using reduction in fluorescence polarization value due to increased molecular volume while binding. The formation of fluorescent adduct in hemoglobin in the advanced stage of glycation and the non-fluorescent HbA 1c will be of major use in distinguishing and to know the past status of diabetes mellitus. While autofluorescence correlated highly with HbA 1c value under in vivo condition ( r=0.85), it was moderate in the clinical samples ( r=0.55). The results suggest a non-linear relation between glycemia and glycation, indicating the application of Hb-AGE as a measure of susceptibility to glycation rather than glycation itself.

  19. Nifedipine, a calcium channel blocker, inhibits advanced glycation end product (AGE)-elicited mesangial cell damage by suppressing AGE receptor (RAGE) expression via peroxisome proliferator-activated receptor-gamma activation

    SciTech Connect

    Matsui, Takanori; Yamagishi, Sho-ichi; Takeuchi, Masayoshi; Ueda, Seiji; Fukami, Kei; Okuda, Seiya

    2009-07-24

    The interaction between advanced glycation end products (AGE) and their receptor RAGE mediates the progressive alteration in renal architecture and loss of renal function in diabetic nephropathy. Oxidative stress generation and inflammation also play a central role in diabetic nephropathy. This study investigated whether and how nifedipine, a calcium channel blocker (CCB), blocked the AGE-elicited mesangial cell damage in vitro. Nifedipine, but not amlodipine, a control CCB, down-regulated RAGE mRNA levels and subsequently reduced reactive oxygen species (ROS) generation in AGE-exposed mesangial cells. AGE increased mRNA levels of vascular cell adhesion molecule-1 (VCAM-1) and induced monocyte chemoattractant protein-1 (MCP-1) production in mesangial cells, both of which were prevented by the treatment with nifedipine, but not amlodipine. The beneficial effects of nifedipine on AGE-exposed mesangial cells were blocked by the simultaneous treatment of GW9662, an inhibitor of peroxisome proliferator-activated receptor-{gamma} (PPAR-{gamma}). Although nifedipine did not affect expression levels of PPAR-{gamma}, it increased the PPAR-{gamma} transcriptional activity in mesangial cells. Our present study provides a unique beneficial aspect of nifedipine on diabetic nephropathy; it could work as an anti-inflammatory agent against AGE by suppressing RAGE expression in cultured mesangial cells via PPAR-{gamma} activation.

  20. Advanced glycation end products in renal failure: an overview.

    PubMed

    Noordzij, M J; Lefrandt, J D; Smit, A J

    2008-12-01

    The article aims to present an overview of the existing knowledge on advanced glycation end products (AGE). They are moieties that bind to proteins, but also lipids and nuclear acids. AGE are formed during glycation and oxidative stress. Accumulation of AGE occurs especially in diabetes and chronic renal failure and plays a major pathogenetic role. The deleterious effects of AGE result from cross-linking of proteins and activation of the receptor for advanced glycation end products. AGE accumulation can be noninvasively assessed by the skin autofluorescence reader. In diabetics, the skin autofluorescence predicts cardiac mortality and the occurrence of macro- and microvascular complications. In patients on haemodialysis, skin autofluorescence is highly elevated and predicts mortality. After renal transplantation AGE accumulation is lower than during haemodialysis, but still remains elevated and is a strong risk factor for chronic renal transplant dysfunction. Some of the potential methods to intervene with AGE accumulation are discussed in this article.

  1. Chemical Reactivity Theory Study of Advanced Glycation Endproduct Inhibitors.

    PubMed

    Frau, Juan; Glossman-Mitnik, Daniel

    2017-02-02

    Several compounds with the known ability to perform as inhibitors of advanced glycation endproducts (AGE) have been studied with Density Functional Theory (DFT) through the use of anumberofdensityfunctionalswhoseaccuracyhasbeentestedacrossabroadspectrumofdatabases in Chemistry and Physics. The chemical reactivity descriptors for these systems have been calculated through Conceptual DFT in an attempt to relate their intrinsic chemical reactivity with the ability to inhibit the action of glycating carbonyl compounds on amino acids and proteins. This knowledge could be useful in the design and development of new drugs which can be potential medicines for diabetes and Alzheimer's disease.

  2. Advanced Glycation End-products and Bone Fractures

    PubMed Central

    Vashishth, Deepak

    2015-01-01

    Bone does not turn over uniformly, and becomes susceptible to post-translational modification by non-enzymatic glycation (NEG). NEG of bone causes the formation of advanced glycation end-products (AGEs) and this process is accelerated with aging, diabetes and antiresorptive postmenopausal osteoporosis therapy. Due to the elevated incidence of fracture associated with aging and diabetes, several studies have attempted to measure and evaluate AGEs as biomarkers for fracture risk. Here current methods of estimating AGEs in bone by liquid chromatography and fluorometric assay are summarized and the relationships between AGEs and fracture properties at whole bone, apparent tissue and matrix levels are discussed. PMID:27158323

  3. Coptis chinensis Polysaccharides Inhibit Advanced Glycation End Product Formation.

    PubMed

    Yang, Ye; Li, Yun; Yin, Dengke; Chen, Song; Gao, Xiangdong

    2016-06-01

    Coptis chinensis Franch (Huanglian) is commonly used to treat diabetes in China. In this study, the effects of the C. chinensis Franch polysaccharides (CCP) on advanced glycation end product (AGE) formation in vitro and in streptozotocin-induced diabetic mice were investigated. CCP significantly inhibited all the three periods of nonenzymatic protein glycation in vitro, including Amadori product, dicarbonyl compound, and AGE formation (P < .01). In diabetic mice, the administration of CCP not only improved both bodyweight and serum insulin and decreased fasting blood glucose and glycated serum protein concentrations but also decreased the AGE accumulations and morphological abnormalities in pancreas and liver. The inhibitory effects of CCP on AGE formation afford a potential therapeutic use in the prevention and treatment of diabetes.

  4. Advanced-glycation-end-product-cholesterol-aggregated-protein accelerates the proliferation of mesangial cells mediated by transforming-growth-factor-beta 1 receptors and the ERK-MAPK pathway.

    PubMed

    Hirasawa, Yasushi; Sakai, Takayuki; Ito, Masanori; Yoshimura, Hiromitsu; Feng, Yibin; Nagamatsu, Tadashi

    2011-12-15

    Hyperglycemia and hyperlipidemia are considered critical to the development of diabetic nephropathy. The aim of this study is to clarify the effect of cholesterol on advanced-glycation-end-products and the mechanisms behind the advanced-glycation-end-product-cholesterol-aggregated bovine serum albumin (BSA)-induced proliferation of mesangial cells. Mesangial cells were treated with advanced-glycation-end-product-cholesterol-aggregated-BSA, and RNA and protein were isolated. Cholesterol caused a 1.5-fold increase in fluorescent intensity and 2-fold increase in advanced-glycation-end-products in vitro. Pyridoxamine, aminoguanidine, and N-acetyl-l-cycteine suppressed the production of advanced-glycation-end-product-cholesterol-aggregated-BSA. Advanced-glycation-end-product-cholesterol-BSA was analyzed by matrix-assisted-laser-desorption/ionization-time of flight mass spectrometry, and peaks were found to shift toward a higher mass. Advanced-glycation-end-product-cholesterol-aggregated-BSA induced overexpression of the mRNA of transforming growth factor-beta1, collagen type 1, collagen type 4 and receptor for advanced-glycation-end-products, and the proliferation of mesangial cells. The injection of advanced-glycation-end-product-cholesterol-aggregated-BSA caused glomerular changes and albuminuria in non-diabetic mice. A transforming-growth-factor-beta receptor 1 kinase inhibitor or Mitogen-activated-Protein-Kinase/Extracellular-Signal-regulated-Kinase kinase (ERK) inhibitor (U-0126) suppressed the proliferation of mesangial cells induced by advanced-glycation-end-product-cholesterol-aggregated-BSA dose-dependently. U-0126 inhibited the phosphorylation of ERK1/2 in advanced-glycation-end-product-cholesterol-aggregated-BSA treated mesangial cells. These findings suggested that cholesterol promotes the formation of advanced-glycation-end-products-protein and that advanced-glycation-end-product-cholesterol-aggregated protein stimulates mesangial cells to proliferate via

  5. Advanced glycation end products (AGEs), but not high glucose, inhibit the osteoblastic differentiation of mouse stromal ST2 cells through the suppression of osterix expression, and inhibit cell growth and increasing cell apoptosis.

    PubMed

    Okazaki, Kyoko; Yamaguchi, Toru; Tanaka, Ken-Ichiro; Notsu, Masakazu; Ogawa, Noriko; Yano, Shozo; Sugimoto, Toshitsugu

    2012-10-01

    Diabetes mellitus is known to be associated with osteoporotic fractures through a decrease in osteoblastic bone formation rather than an increase in osteoclastic bone resorption. However, its precise mechanism is unknown, and we examined whether or not high glucose or advanced glycation end products (AGEs), which play key roles in the pathogenesis and complications of diabetes, would affect the osteoblastic differentiation, growth, and apoptosis of mouse stromal ST2 cells. Ten to 200 μg/mL AGE2 or AGE3 alone dose-dependently inhibited the mineralization. AGE2 or AGE3 alone (200 μg/mL) significantly inhibited alkaline phosphatase (ALP) activities as well as the mineralization of the cells (p < 0.01). In contrast, 22 mM glucose alone or in combination with 200 μg/mL AGE2 or AGE3 did not affect these cellular phenotypes. Real-time PCR showed that AGE2 or AGE3 alone (200 μg/mL) significantly decreased mRNA expressions of osteocalcin as well as osterix on day 14 (p < 0.01). Western blot analysis showed that AGE2 or AGE3 alone (200 μg/mL) also decreased the levels of Runx2 and osterix protein expressions on days 7 and 14. AGE2 or AGE3 significantly suppressed cell growth and increased apoptotic cell death in time- and dose-dependent manners (p < 0.01). Moreover, AGE3 alone (200 μg/mL) significantly increased mRNA expression of the receptor for AGEs (RAGE) on days 2 and 3 (p < 0.01). These results suggest that AGE2 and AGE3, but not high glucose, may inhibit the osteoblastic differentiation of stromal cells by decreasing osterix expression and partly by increasing RAGE expression, as well as inhibiting cell growth and increasing cell apoptosis.

  6. Uremic Toxicity of Advanced Glycation End Products in CKD.

    PubMed

    Stinghen, Andréa E M; Massy, Ziad A; Vlassara, Helen; Striker, Gary E; Boullier, Agnès

    2016-02-01

    Advanced glycation end products (AGEs), a heterogeneous group of compounds formed by nonenzymatic glycation reactions between reducing sugars and amino acids, lipids, or DNA, are formed not only in the presence of hyperglycemia, but also in diseases associated with high levels of oxidative stress, such as CKD. In chronic renal failure, higher circulating AGE levels result from increased formation and decreased renal clearance. Interactions between AGEs and their receptors, including advanced glycation end product-specific receptor (RAGE), trigger various intracellular events, such as oxidative stress and inflammation, leading to cardiovascular complications. Although patients with CKD have a higher burden of cardiovascular disease, the relationship between AGEs and cardiovascular disease in patients with CKD is not fully characterized. In this paper, we review the various deleterious effects of AGEs in CKD that lead to cardiovascular complications and the role of these AGEs in diabetic nephropathy. We also discuss potential pharmacologic approaches to circumvent these deleterious effects by reducing exogenous and endogenous sources of AGEs, increasing the breakdown of existing AGEs, or inhibiting AGE-induced inflammation. Finally, we speculate on preventive and therapeutic strategies that focus on the AGE-RAGE axis to prevent vascular complications in patients with CKD.

  7. Advanced glycation end-products inhibitors isolated from Schisandra grandiflora.

    PubMed

    Poornima, B; Kumar, D Anand; Siva, Bandi; Venkanna, A; Vadaparthi, P R Rao; Kumar, K; Tiwari, Ashok K; Babu, K Suresh

    2016-01-01

    Free radicals scavenging and advanced glycation end-products (AGEs) inhibitory potentials in crude chloroform extract of Schisandra grandiflora were evaluated. Bioassay-guided isolation of the chloroform extract led to the identification of 24 compounds. Among the isolates, ( ± ) gomisin M1, arisantetralone C and D, macelignan, saurulignan B and SZ-MO displayed potent-free radical scavenging as well as AGEs inhibitory potentials. This is the first report identifying the presence of AGEs inhibitory activity and assigning AGEs inhibitory activity to these compounds. Therefore, our research finds new application of traditional medicinal plant S. grandiflora having capacity to reduce formation and accumulation of AGEs in diabetes.

  8. Vascular Effects of Dietary Advanced Glycation End Products

    PubMed Central

    Stirban, Alin; Tschöpe, Diethelm

    2015-01-01

    Evidence has accumulated lately demonstrating that advanced glycation end products (AGEs) play an important role in the development of diabetic and cardiovascular complications as well as the development of other chronic diseases. AGEs originating from diet have a significant contribution to the AGEs body pool and therefore dietary interventions aiming at reducing AGEs load are believed to exert health promoting effects. This review summarizes the evidence from clinical studies regarding effects of dietary AGEs on the vascular system, highlighting also the different aspects of vascular tests. It also advocates an extension of dietary recommendations towards the promotion of cooking methods that reduce dietary AGEs in consumed foods. PMID:26089897

  9. Advanced Glycation End-Product Accumulation Reduces Vitreous Permeability

    PubMed Central

    Lee, On-Tat; Good, Samuel D.; Lamy, Ricardo; Kudisch, Max; Stewart, Jay M.

    2015-01-01

    Purpose. To evaluate the effect of nonenzymatic cross-linking (glycation) upon the permeability of the vitreous to small- and large-solute diffusion. Methods. Vitreous from freshly excised porcine eyes was treated for 30 minutes with control or 0.01%, 0.1%, or 1% methylglyoxal (MG) solution. The efficacy of the glycation regimen was verified by measuring nonenzymatic cross-link density by fluorescence in the vitreous samples. Resistance to collagenase digestion as well as Nε-(carboxyethyl) lysine (CEL) content were also measured. The permeability coefficient for fluorescein and fluorescein isothiocyanate (FITC)-IgG diffusion through 3 mL of the vitreous samples was determined by using a custom permeability tester. Results. Vitreous cross-linking with MG treatment was confirmed by increased fluorescence, increased CEL concentration, and increased resistance to collagenase digestion. Vitreous glycation resulted in a statistically significant decrease in the permeability coefficient for fluorescein diffusion when either 0.1% or 1% MG solution was used (5.36 ± 5.24 × 10−5 cm s−1, P = 0.04; and 4.03 ± 2.1 × 10−5 cm s−1, P = 0.001; respectively, compared with control, 9.77 ± 5.45 × 10−5 cm s−1). The permeability coefficient for diffusion of FITC-IgG between control (9.9 ± 6.37 × 10−5 cm s−1) and treatment groups was statistically significant at all MG concentrations (0.01% MG: 3.95 ± 3.44 × 10−5 cm s−1, P = 0.003; 0.1% MG: 4.27 ± 1.32 × 10−5 cm s−1, P = 0.004; and 0.1% MG: 3.72 ± 2.49 × 10−5 cm s−1, P = 0.001). Conclusions. Advanced glycation end-product (AGE) accumulation reduces vitreous permeability when glycation is performed in ex vivo porcine vitreous. The permeability change was more pronounced for the larger solute, suggesting a lower threshold for AGE-induced permeability changes to impact the movement of proteins through the vitreous when compared with smaller molecules. PMID:26024075

  10. Methylglyoxal-Derived Advanced Glycation Endproducts in Multiple Sclerosis

    PubMed Central

    Wetzels, Suzan; Wouters, Kristiaan; Schalkwijk, Casper G.; Vanmierlo, Tim; Hendriks, Jerome J. A.

    2017-01-01

    Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS). The activation of inflammatory cells is crucial for the development of MS and is shown to induce intracellular glycolytic metabolism in pro-inflammatory microglia and macrophages, as well as CNS-resident astrocytes. Advanced glycation endproducts (AGEs) are stable endproducts formed by a reaction of the dicarbonyl compounds methylglyoxal (MGO) and glyoxal (GO) with amino acids in proteins, during glycolysis. This suggests that, in MS, MGO-derived AGEs are formed in glycolysis-driven cells. MGO and MGO-derived AGEs can further activate inflammatory cells by binding to the receptor for advanced glycation endproducts (RAGE). Recent studies have revealed that AGEs are increased in the plasma and brain of MS patients. Therefore, AGEs might contribute to the inflammatory status in MS. Moreover, the main detoxification system of dicarbonyl compounds, the glyoxalase system, seems to be affected in MS patients, which may contribute to high MGO-derived AGE levels. Altogether, evidence is emerging for a contributing role of AGEs in the pathology of MS. In this review, we provide an overview of the current knowledge on the involvement of AGEs in MS. PMID:28212304

  11. Methylglyoxal-Derived Advanced Glycation Endproducts in Multiple Sclerosis.

    PubMed

    Wetzels, Suzan; Wouters, Kristiaan; Schalkwijk, Casper G; Vanmierlo, Tim; Hendriks, Jerome J A

    2017-02-15

    Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS). The activation of inflammatory cells is crucial for the development of MS and is shown to induce intracellular glycolytic metabolism in pro-inflammatory microglia and macrophages, as well as CNS-resident astrocytes. Advanced glycation endproducts (AGEs) are stable endproducts formed by a reaction of the dicarbonyl compounds methylglyoxal (MGO) and glyoxal (GO) with amino acids in proteins, during glycolysis. This suggests that, in MS, MGO-derived AGEs are formed in glycolysis-driven cells. MGO and MGO-derived AGEs can further activate inflammatory cells by binding to the receptor for advanced glycation endproducts (RAGE). Recent studies have revealed that AGEs are increased in the plasma and brain of MS patients. Therefore, AGEs might contribute to the inflammatory status in MS. Moreover, the main detoxification system of dicarbonyl compounds, the glyoxalase system, seems to be affected in MS patients, which may contribute to high MGO-derived AGE levels. Altogether, evidence is emerging for a contributing role of AGEs in the pathology of MS. In this review, we provide an overview of the current knowledge on the involvement of AGEs in MS.

  12. Early- and advanced non-enzymatic glycation in diabetic vascular complications: the search for therapeutics.

    PubMed

    Schalkwijk, Casper G; Miyata, Toshio

    2012-04-01

    Cardiovascular disease is a common complication of diabetes and the leading cause of death among people with diabetes. Because of the huge premature morbidity and mortality associated with diabetes, prevention of vascular complications is a key issue. Although the exact mechanism by which vascular damage occurs in diabetes in not fully understood, numerous studies support the hypothesis of a causal relationship of non-enzymatic glycation with vascular complications. In this review, data which point to an important role of Amadori-modified glycated proteins and advanced glycation endproducts in vascular disease are surveyed. Because of the potential role of early- and advanced non-enzymatic glycation in vascular complications, we also described recent developments of pharmacological inhibitors that inhibit the formation of these glycated products or the biological consequences of glycation and thereby retard the development of vascular complications in diabetes.

  13. The Mechanisms of Inhibition of Advanced Glycation End Products Formation through Polyphenols in Hyperglycemic Condition.

    PubMed

    Khangholi, Shahpour; Majid, Fadzilah Adibah Abdul; Berwary, Najat Jabbar Ahmed; Ahmad, Farediah; Aziz, Ramlan Bin Abd

    2016-01-01

    Glycation, the non-enzymatic binding of glucose to free amino groups of an amino acid, yields irreversible heterogeneous compounds known as advanced glycation end products. Those products play a significant role in diabetic complications. In the present article we briefly discuss the contribution of advanced glycation end products to the pathogenesis of diabetic complications, such as atherosclerosis, diabetic retinopathy, nephropathy, neuropathy, and wound healing. Then we mention the various mechanisms by which polyphenols inhibit the formation of advanced glycation end products. Finally, recent supporting documents are presented to clarify the inhibitory effects of polyphenols on the formation of advanced glycation end products. Phytochemicals apply several antiglycation mechanisms, including glucose metabolism, amelioration of oxidative stress, scavenging of dicarbonyl species, and up/down-regulation of gene expression. To utilize polyphenols in order to remedy diabetic complications, we must explore, examine and clarify the action mechanisms of the components of polyphenols.

  14. Mangiferin suppressed advanced glycation end products (AGEs) through NF-κB deactivation and displayed anti-inflammatory effects in streptozotocin and high fat diet-diabetic cardiomyopathy rats.

    PubMed

    Hou, Jun; Zheng, Dezhi; Fung, Gabriel; Deng, Haoyu; Chen, Lin; Liang, Jiali; Jiang, Yan; Hu, Yonghe

    2016-03-01

    Given the importance of the aggregation of advanced glycation end products (AGEs) and cardiac inflammation in the onset and progression of diabetic cardiomyopathy (DCM), our objective in this study was to demonstrate the cardioprotective effect of mangiferin, an antidiabetic and anti-inflammatory agent, on diabetic rat model. The DCM model was established by a high-fat diet and a low dose of streptozotocin. DCM rats were treated orally with mangiferin (20 mg/kg) for 16 weeks. Serum and left ventricular myocardium were collected for determination of inflammatory cytokines. AGEs mRNA and protein expression of nuclear factor kappa B (NF-κB) and receptor for AGEs (RAGE) in myocardium were assayed by real-time PCR and Western blot. ROS levels were measured by dihydroethidium fluorescence staining. NF-κB binding activity was assayed by TransAM NF-κB p65 ELISA kit. Chronic treatment with mangiferin decreased the levels of myocardial enzymes (CK-MB, LDH) and inflammatory mediators (TNF-α, IL-1β). Meanwhile, NF-κB is inhibited by the reduction of nuclear translocation of p65 subunit, and mangiferin reduced AGE production and decreased the mRNA and protein expression of RAGE in DCM rats. Our data indicated that mangiferin could significantly ameliorate DCM by preventing the release of inflammatory cytokines, and inhibiting ROS accumulation, AGE/RAGE production, and NF-κB nuclear translocation, suggesting that mangiferin treatment might be beneficial in DCM.

  15. Advanced glycation endproducts and diabetes. Beyond vascular complications.

    PubMed

    Puddu, Alessandra; Viviani, Giorgio L

    2011-06-01

    Advanced Glycation Endproducts (AGEs) are a group of heterogeneous compounds formed by the non enzymatic reactions between aldehydic group of reducing sugars with proteins, lipids or nucleic acids. Formation and accumulation of AGEs is related with the aging process and is accelerated in diabetes. Type 2 diabetes, the most common form of diabetes, is characterized by hyperglycaemia and insulin resistance associated to a progressive deterioration of beta cell function and mass. The pathogenic role of AGEs in vascular diabetic complications is widely recognised. Recently other aspects of the detrimental effects of AGEs in type 2 diabetes are emerged: AGEs interfere with the complex molecular pathway of insulin signaling, leading to insulin resistance; AGEs modify the insulin molecule, and, consequently, its function; AGEs decrease insulin secretion and insulin content. In this article we review the role of AGEs in type 2 diabetes, beyond their involvement in vascular complications.

  16. Clinical relevance of advanced glycation endproducts for vascular surgery.

    PubMed

    Meerwaldt, R; van der Vaart, M G; van Dam, G M; Tio, R A; Hillebrands, J-L; Smit, A J; Zeebregts, C J

    2008-08-01

    Atherosclerosis is the main contributor to cardiovascular disease and leads to intimal plaque formation, which may progress to plaque rupture with subsequent thromboembolic events and/or occlusion of the arterial lumen. There is increasing evidence that the development or progression of atherosclerosis is associated with advanced glycation endproducts (AGEs). AGEs are a heterogeneous group of compounds formed by the non-enzymatic reaction of reducing sugars with proteins, lipids, and nucleic acids. An increased understanding of the mechanisms of formation and interaction of AGEs has allowed the development of several potential anti-AGE strategies. This review summarizes AGE formation and biochemistry, the pathogeneic role of AGEs in cardiovascular disease, anti-AGE therapies and clinical relevance to vascular surgery.

  17. Determination of advanced glycation endproducts in cooked meat products.

    PubMed

    Chen, Gengjun; Smith, J Scott

    2015-02-01

    Advanced glycation endproducts (AGEs), a pathogenic factor implicated in diabetes and other chronic diseases, are produced in cooked meat products. The objective of this study was to determine the AGE content, as measured by Nε-carboxymethyllysine (CML) levels, in cooked chicken, pork, beef and fish (salmon and tilapia) prepared by three common cooking methods used by U.S. consumers: frying, baking, and broiling. The CML was detected in all the cooked samples, but the levels were dependent on types of meat, cooking conditions, and the final internal temperature. Broiling and frying at higher cooking temperature produced higher levels of CML, and broiled beef contained the highest CML content (21.8μg/g). Baked salmon (8.6μg/g) and baked tilapia (9.7μg/g) contained less CML as compared to the other muscle food samples.

  18. Advanced glycation end products increase carbohydrate responsive element binding protein expression and promote cancer cell proliferation.

    PubMed

    Chen, Hanbei; Wu, Lifang; Li, Yakui; Meng, Jian; Lin, Ning; Yang, Dianqiang; Zhu, Yemin; Li, Xiaoyong; Li, Minle; Xu, Ye; Wu, Yuchen; Tong, Xuemei; Su, Qing

    2014-09-01

    Diabetic patients have increased levels of advanced glycation end products (AGEs) and the role of AGEs in regulating cancer cell proliferation is unclear. Here, we found that treating colorectal and liver cancer cells with AGEs promoted cell proliferation. AGEs stimulated both the expression and activation of a key transcription factor called carbohydrate responsive element binding protein (ChREBP) which had been shown to promote glycolytic and anabolic activity as well as proliferation of colorectal and liver cancer cells. Using siRNAs or the antagonistic antibody for the receptor for advanced glycation end-products (RAGE) blocked AGEs-induced ChREBP expression or cell proliferation in cancer cells. Suppressing ChREBP expression severely impaired AGEs-induced cancer cell proliferation. Taken together, these results demonstrate that AGEs-RAGE signaling enhances cancer cell proliferation in which AGEs-mediated ChREBP induction plays an important role. These findings may provide new explanation for increased cancer progression in diabetic patients.

  19. Preparation of nucleotide advanced glycation endproducts--imidazopurinone adducts formed by glycation of deoxyguanosine with glyoxal and methylglyoxal.

    PubMed

    Fleming, Thomas; Rabbani, Naila; Thornalley, Paul J

    2008-04-01

    An analytical procedure was developed for nucleotide advanced glycation endproducts formed by the reaction of glyoxal and methylglyoxal with deoxyguanosine under physiological conditions. For this, the imidazopurinone derivatives, 3-(2'-deoxyribosyl)-6,7-dihydro-6,7-dihydroxyimidazo[2,3-b]purin-9(8)one (dG-G) and 3-(2'-deoxyribosyl)-6,7-dihydro-6,7-dihydroxy-6-methylimidazo-[2,3-b]purine-9(8)one (dG-MG), were prepared. Authentic standard and stable isotope-substituted standard adducts were prepared and an isotopic dilution analysis assay methodology was developed using liquid chromatography with tandem mass spectrometry and optimized DNA extraction and nuclease digestion procedures. Analysis of dG-G, dG-MG, and the oxidative marker 8-hydroxydeoxyguanosine in the DNA of cultured human cells and mononuclear leukocytes showed that nucleotide advanced glycation endproducts are major markers of DNA damage in human cells.

  20. Advanced glycation end products contribute to amyloidosis in Alzheimer disease.

    PubMed Central

    Vitek, M P; Bhattacharya, K; Glendening, J M; Stopa, E; Vlassara, H; Bucala, R; Manogue, K; Cerami, A

    1994-01-01

    Alzheimer disease (AD) is characterized by deposits of an aggregated 42-amino-acid beta-amyloid peptide (beta AP) in the brain and cerebrovasculature. After a concentration-dependent lag period during in vitro incubations, soluble preparations of synthetic beta AP slowly form fibrillar aggregates that resemble natural amyloid and are measurable by sedimentation and thioflavin T-based fluorescence. Aggregation of soluble beta AP in these in vitro assays is enhanced by addition of small amounts of pre-aggregated beta-amyloid "seed" material. We also have prepared these seeds by using a naturally occurring reaction between glucose and protein amino groups resulting in the formation of advanced "glycosylation" end products (AGEs) which chemically crosslink proteins. AGE-modified beta AP-nucleation seeds further accelerated aggregation of soluble beta AP compared to non-modified "seed" material. Over time, nonenzymatic advanced glycation also results in the gradual accumulation of a set of posttranslational covalent adducts on long-lived proteins in vivo. In a standardized competitive ELISA, plaque fractions of AD brains were found to contain about 3-fold more AGE adducts per mg of protein than preparations from healthy, age-matched controls. These results suggest that the in vivo half-life of beta-amyloid is prolonged in AD, resulting in greater accumulation of AGE modifications which in turn may act to promote accumulation of additional amyloid. PMID:8197133

  1. Advanced glycation end-products: modifiable environmental factors profoundly mediate insulin resistance

    PubMed Central

    Ottum, Mona S.; Mistry, Anahita M.

    2015-01-01

    Advanced glycation end-products are toxic by-products of metabolism and are also acquired from high-temperature processed foods. They promote oxidative damage to proteins, lipids and nucleotides. Aging and chronic diseases are strongly associated with markers for oxidative stress, especially advanced glycation end-products, and resistance to peripheral insulin-mediated glucose uptake. Modifiable environmental factors including high levels of refined and simple carbohydrate diets, hypercaloric diets and sedentary lifestyles drive endogenous formation of advanced glycation end-products via accumulation of highly reactive glycolysis intermediates and activation of the polyol/aldose reductase pathway producing high intracellular fructose. High advanced glycation end-products overwhelm innate defenses of enzymes and receptor-mediated endocytosis and promote cell damage via the pro-inflammatory and pro-oxidant receptor for advanced glycation end-products. Oxidative stress disturbs cell signal transduction, especially insulin-mediated metabolic responses. Here we review emerging evidence that restriction of dietary advanced glycation end-products significantly reduces total systemic load and insulin resistance in animals and humans in diabetes, polycystic ovary syndrome, healthy populations and dementia. Of clinical importance, this insulin sensitizing effect is independent of physical activity, caloric intake and adiposity level. PMID:26236094

  2. Reduced formation of advanced glycation endproducts via interactions between glutathione peroxidase 3 and dihydroxyacetone kinase 1.

    PubMed

    Lee, Hana; Chi, Seung Wook; Lee, Phil Young; Kang, Sunghyun; Cho, Sayeon; Lee, Chong-Kil; Bae, Kwang-Hee; Park, Byoung Chul; Park, Sung Goo

    2009-11-06

    Dihydroxyacetone (DHA) induces the formation of advanced glycation endproducts (AGEs), which are involved in several diseases. Earlier, we identified dihydroxyacetone kinase 1 (Dak1) as a candidate glutathione peroxidase 3 (Gpx3)-interacting protein in Saccharomyces cerevisiae. This finding is noteworthy, as no clear evidence on the involvement of oxidative stress systems in DHA-induced AGE formation has been found to date. Here, we demonstrate that Gpx3 interacts with Dak1, alleviates DHA-mediated stress by upregulating Dak activity, and consequently suppresses AGE formation. Based on these results, we propose that defense systems against oxidative stress and DHA-induced AGE formation are related via interactions between Gpx3 and Dak1.

  3. Advanced glycation end products in degenerative nucleus pulposus with diabetes.

    PubMed

    Tsai, Tsung-Ting; Ho, Natalie Yi-Ju; Lin, Ying-Ting; Lai, Po-Liang; Fu, Tsai-Sheng; Niu, Chi-Chien; Chen, Lih-Huei; Chen, Wen-Jer; Pang, Jong-Hwei S

    2014-02-01

    Diabetes mellitus (DM) has been clinically proved as a risk factor of disc degeneration, and the accumulation of advanced glycation end products (AGEs) is known to be potentially involved in diabetes. The purpose of this study is to investigate the effect of AGEs in the degeneration process of diabetic nucleus pulposus (NP) in rats and humans. Diabetic NP cells from rat coccygeal discs were treated with different concentrations of AGEs (0, 50, and 100 µg/ml) for 3 days, and mRNA expressions of MMP-2 and RAGE were measured by real-time RT-PCR. In addition, conditioned medium from NP cells was used to analyze protein expression of MMP-2 activity and ERK by gelatin zymography and Western blot. These experiments were repeated using human intervertebral disc samples. The immunohistochemical expression of AGEs was significantly increased in diabetic discs. In response to AGEs, an increase of MMP-2, RAGE, and ERK at both mRNA and protein expression levels was observed in diabetic NP cells. The findings suggest that AGEs and DM are associated with disc degeneration in both species. Hyperglycemia in diabetes enhances the accumulation of AGEs in the NP and triggers disc degeneration.

  4. Immunological detection of a novel advanced glycation end-product.

    PubMed Central

    Takeuchi, M.; Yanase, Y.; Matsuura, N.; Yamagishi Si, S.; Kameda, Y.; Bucala, R.; Makita, Z.

    2001-01-01

    BACKGROUND: The advanced stage of the Maillard reaction that leads to the formation of advanced glycation end-products (AGEs) plays an important role in the pathogenesis of angiopathy in diabetic patients and in the aging process. Recently, it has been proposed that the intermediates contributing to AGE formation include dicarbonyl intermediates such as glyoxal, methylglyoxal, and 3-deoxyglucosone (3-DG). In the present study, we developed a novel, non-carboxymethyllysine (CML) anti-AGE antibody that recognizes serum proteins and peptides modified by 3-DG in vivo. MATERIALS AND METHODS: AGE-modified serum albumins were prepared by incubation of rabbit serum albumin with 3-DG or D-glucose. After immunization of rabbits, anti-AGE antisera were subjected to affinity chromatography on a Sepharose 4B column coupled with CML-BSA, or AGE-BSA created by incubation with 3-DG (AGE-6) or D-glucose (AGE-1). The AGE-Ab-6 and AGE-Ab-1 thus obtained was used to investigate AGEs in serum from diabetic patients on hemodialysis. RESULTS: Characterization of the novel AGE-Ab-6 obtained by immunoaffinity chromatography was performed with a competitive ELISA and immunoblot analysis. This antibody specifically cross-reacted with proteins modified by 3-DG. AGE-6 was detected in diabetic serum as three peaks with apparent molecular weights of 200, 1.15, and 0.85 kD, while AGE-1 was detected as four peaks with apparent molecular weights of 200, 65, 1.15, and 0.85 kD. CONCLUSION: This study provides new data on the pathways of AGE formation from 3-DG and methods for the immunochemical detection of AGEs. We also provide immunochemical evidence for the existence of six distinct AGEs in vivo among the AGE-modified proteins and peptides in the serum of diabetic patients on hemodialysis. PMID:11788793

  5. Stimulatory effects of advanced glycation endproducts (AGEs) on fibronectin matrix assembly.

    PubMed

    Pastino, Alexandra K; Greco, Todd M; Mathias, Rommel A; Cristea, Ileana M; Schwarzbauer, Jean E

    2017-05-01

    Advanced glycation endproducts (AGEs) are a heterogeneous group of compounds that form via non-enzymatic glycation of proteins throughout our lifespan and at a higher rate in certain chronic diseases such as diabetes. AGEs contribute to the progression of fibrosis, in part by stimulating cellular pathways that affect gene expression. Long-lived ECM proteins are targets for non-enzymatic glycation but the question of whether the AGE-modified ECM leads to excess ECM accumulation and fibrosis remains unanswered. In this study, cellular changes due to AGE accretion in the ECM were investigated. Non-enzymatic glycation of proteins in a decellularized fibroblast ECM was achieved by incubating the ECM in a solution of methylglyoxal (MGO). Mass spectrometry of fibronectin (FN) isolated from the glycated matrix identified twenty-eight previously unidentified MGO-derived AGE modification sites including functional sites such as the RGD integrin-binding sequence. Mesangial cells grown on the glycated, decellularized matrix assembled increased amounts of FN matrix. Soluble AGE-modified bovine serum albumin (BSA) also stimulated FN matrix assembly and this effect was reduced by function-blocking antibodies against the receptor for AGE (RAGE). These results indicate that cells respond to AGEs by increasing matrix assembly and that RAGE is involved in this response. This raises the possibility that the accumulation of ECM during the progression of fibrosis may be enhanced by cell interactions with AGEs on a glycated ECM.

  6. Glycation inhibitors extend yeast chronological lifespan by reducing advanced glycation end products and by back regulation of proteins involved in mitochondrial respiration.

    PubMed

    Kazi, Rubina S; Banarjee, Reema M; Deshmukh, Arati B; Patil, Gouri V; Jagadeeshaprasad, Mashanipalya G; Kulkarni, Mahesh J

    2017-03-06

    Advanced Glycation End products (AGEs) are implicated in aging process. Thus, reducing AGEs by using glycation inhibitors may help in attenuating the aging process. In this study using Saccharomyces cerevisiae yeast system, we show that Aminoguanidine (AMG), a well-known glycation inhibitor, decreases the AGE modification of proteins in non-calorie restriction (NR) (2% glucose) and extends chronological lifespan (CLS) similar to that of calorie restriction (CR) condition (0.5% glucose). Proteomic analysis revealed that AMG back regulates the expression of differentially expressed proteins especially those involved in mitochondrial respiration in NR condition, suggesting that it switches metabolism from fermentation to respiration, mimicking CR. AMG induced back regulation of differentially expressed proteins could be possibly due to its chemical effect or indirectly by glycation inhibition. To delineate this, Metformin (MET), a structural analog of AMG and a mild glycation inhibitor and Hydralazine (HYD), another potent glycation inhibitor but not structural analog of AMG were used. HYD was more effective than MET in mimicking AMG suggesting that glycation inhibition was responsible for restoration of differentially expressed proteins. Thus glycation inhibitors particularly AMG, HYD and MET extend yeast CLS by reducing AGEs, modulating the expression of proteins involved in mitochondrial respiration and possibly by scavenging glucose.

  7. Genistein inhibits advanced glycation end product formation by trapping methylglyoxal.

    PubMed

    Lv, Lishuang; Shao, Xi; Chen, Huadong; Ho, Chi-Tang; Sang, Shengmin

    2011-04-18

    Methylglyoxal (MGO) is a highly reactive endogenous metabolite derived from several nonenzymatic and enzymatic reactions, and identified as a well-known precursor of advanced glycation end products (AGEs). In the present study, genistein, a naturally occurring isoflavone derived from soy products, demonstrated significant trapping effects of MGO and consequently formed mono- and di-MGO adducts under physiological conditions (pH 7.4, 37 °C). More than 80.0% of MGO was trapped within 4 h, and the trapping efficiency could be up to 97.7% at 24 h. The reaction adducts formed from genistein and MGO under different ratios were analyzed using LC/MS. We also successfully purified and identified the major mono- and di-MGO conjugated adducts of genistein. The NMR data showed that positions 6 and 8 of the A ring of genistein were the major active sites for trapping MGO. We further demonstrated that genistein could effectively inhibit the formation of AGEs in the human serum albumin (HSA)-MGO assay. Two mono-MGO adducts and one di-MGO adduct of genistein were detected in this assay using LC/MS. The di-MGO adduct of genistein became the dominant reaction product during prolonged incubation. Results from this study, as well as our previous findings on (-)-epigallocatechin 3-gallate (EGCG), phloridzin and phloretin, indicate that dietary flavonoids that have the same A ring structure as genistein, EGCG, phloridzin, and phloretin may have the potential to inhibit the formation of AGEs by trapping reactive dicarbonyl species.

  8. Advanced glycation endproducts and rat dental implant osseointegration.

    PubMed

    Quintero, David G; Winger, Julia N; Khashaba, Rania; Borke, James L

    2010-01-01

    Advanced glycation endproducts (AGEs) are a diverse group of molecular adducts formed in environments high in reducing sugars that accumulate with aging and in diabetes. This study tests the hypothesis that AGEs inhibit the stabile osseointegration of dental implants through tissue interactions that interfere with bone turnover and compromise the biomechanical properties at the bone-implant interface. Maxillary first molars were extracted from 32 rats and allowed to heal for 4 weeks. Titanium implants (1 mm x 3 mm) were placed in the healed sockets of 2 groups of 16 rats consisting of 8 rats injected 3 times/wk for 1 month with AGE (prepared from glucose and lysine) and 8 rats injected with vehicle as a control. AGE injections continued for an additional 14 or 28 days before sacrifice. X-ray images, blood, and tissues were collected to examine bone/implant contact ratio, serum pyridinoline ([PYD] a collagen breakdown marker), osteocalcin ([OSC] a bone formation marker), and for immunohistochemistry with antibodies to AGE and the bone turnover-marker protein matrix metalloproteinase1. Compared with the AGE-treated groups, the controls showed significantly higher bone/implant contact at both 14- and 28-day time points. PYD (P < .05) and OSC (trend) levels from controls showed decreases at 28 days when compared with AGE-treated groups. Immunohistochemistry with AGE-specific and bone turnover marker antibodies showed stronger staining associated with the implant/tissue interface in AGE-treated rats. Our studies indicate an association between AGE and inhibition of bone turnover, suggesting that the formation of AGE in high glycemic conditions, such as diabetes, may contribute to a slower rate of osseointegration that negatively affects implant stability.

  9. How Can Diet Affect the Accumulation of Advanced Glycation End-Products in the Human Body?

    PubMed Central

    Guilbaud, Axel; Niquet-Leridon, Celine; Boulanger, Eric; Tessier, Frederic J.

    2016-01-01

    The accumulation of advanced glycation end products (AGEs) is associated with the complications of diabetes, kidney disease, metabolic disorders and degenerative diseases. It is recognized that the pool of glycation products found in the human body comes not only from an endogenous formation, but also from a dietary exposure to exogenous AGEs. In recent years, the development of pharmacologically-active ingredients aimed at inhibiting endogenous glycation has not been successful. Since the accumulation of AGEs in the human body appears to be progressive throughout life, an early preventive action against glycation could be effective through dietary adjustments or supplementation with purified micronutrients. The present article provides an overview of current dietary strategies tested either in vitro, in vivo or both to reduce the endogenous formation of AGEs and to limit exposure to food AGEs. PMID:28231179

  10. Advanced glycation end-products diminish tendon collagen fiber sliding.

    PubMed

    Li, Yufei; Fessel, Gion; Georgiadis, Marios; Snedeker, Jess G

    2013-04-24

    Connective tissue aging and diabetes related comorbidity are associated with compromised tissue function, increased susceptibility to injury, and reduced healing capacity. This has been partly attributed to collagen cross-linking by advanced glycation end-products (AGEs) that accumulate with both age and disease. While such cross-links are believed to alter the physical properties of collagen structures and tissue behavior, existing data relating AGEs to tendon mechanics is contradictory. In this study, we utilized a rat tail tendon model to quantify the micro-mechanical repercussion of AGEs at the collagen fiber-level. Individual tendon fascicles were incubated with methylglyoxal (MGO), a naturally occurring metabolite known to form AGEs. After incubation in MGO solution or buffer only, tendons were stretched on the stage of a multiphoton confocal microscope and individual collagen fiber stretch and relative fiber sliding were quantified. Treatment by MGO yielded increased fluorescence and elevated denaturation temperatures as found in normally aged tissue, confirming formation of AGEs and related cross-links. No apparent ultrastructural changes were noted in transmission electron micrographs of cross-linked fibrils. MGO treatment strongly reduced tissue stress relaxation (p<0.01), with concomitantly increased tissue yield stress (p<0.01) and ultimate failure stress (p=0.036). MGO did not affect tangential modulus in the linear part of the stress-strain curve (p=0.46). Microscopic analysis of collagen fiber kinematics yielded striking results, with MGO treatment drastically reducing fiber-sliding (p<0.01) with a compensatory increase in fiber-stretch (p<0.01). We thus conclude that the main mechanical effect of AGEs is a loss of tissue viscoelasticity driven by matrix-level loss of fiber-fiber sliding. This has potentially important implications to tissue damage accumulation, mechanically regulated cell signaling, and matrix remodeling. It further highlights the

  11. Advanced glycation endproducts in horses with insulin-induced laminitis.

    PubMed

    de Laat, M A; Kyaw-Tanner, M T; Sillence, M N; McGowan, C M; Pollitt, C C

    2012-01-15

    Advanced glycation endproducts (AGEs) have been implicated in the pathogenesis of cancer, inflammatory conditions and diabetic complications. An interaction of AGEs with their receptor (RAGE) results in increased release of pro-inflammatory cytokines and reactive oxygen species (ROS), causing damage to susceptible tissues. Laminitis, a debilitating foot condition of horses, occurs in association with endocrine dysfunction and the potential involvement of AGE and RAGE in the pathogenesis of the disease has not been previously investigated. Glucose transport in lamellar tissue is thought to be largely insulin-independent (GLUT-1), which may make the lamellae susceptible to protein glycosylation and oxidative stress during periods of increased glucose metabolism. Archived lamellar tissue from horses with insulin-induced laminitis (n=4), normal control horses (n=4) and horses in the developmental stages (6h, 12h and 24h) of the disease (n=12) was assessed for AGE accumulation and the presence of oxidative protein damage and cellular lipid peroxidation. The equine-specific RAGE gene was identified in lamellar tissue, sequenced and is now available on GenBank. Lamellar glucose transporter (GLUT-1 and GLUT-4) gene expression was assessed quantitatively with qRT-PCR in laminitic and control horses and horses in the mid-developmental time-point (24 h) of the disease. Significant AGE accumulation had occurred by the onset of insulin-induced laminitis (48 h) but not at earlier time-points, or in control horses. Evidence of oxidative stress was not found in any group. The equine-specific RAGE gene was not expressed differently in treated and control animals, nor was the insulin-dependent glucose transporter GLUT-4. However, the glucose transporter GLUT-1 was increased in lamellar tissue in the developmental stages of insulin-induced laminitis compared to control horses and the insulin-independent nature of the lamellae may facilitate AGE formation. However, due to the lack of

  12. Advanced glycation end products and diabetic nephropathy: a comparative study using diabetic and normal rats with methylglyoxal-induced glycation.

    PubMed

    Rodrigues, Lisa; Matafome, Paulo; Crisóstomo, Joana; Santos-Silva, Daniela; Sena, Cristina; Pereira, Paulo; Seiça, Raquel

    2014-03-01

    Hyperglycemia-related advanced glycation end product (AGE) formation is a key mechanism in diabetic nephropathy. Since methylglyoxal (MG) is a potent AGE precursor, we aimed to assess the role of MG-related AGE formation in the progression of renal damages. A comparative study between Wistar (W, normal) and Goto-Kakizaki (GK, nonobese type 2 diabetic) rats was performed at 6 and 14 months old and after 14 weeks of MG administration to 6-month-old rats. Diabetic rats showed progressive structural, biochemical, and functional alterations, including AGE, albuminuria, and tissue hypoxia, which were partially mimicked by MG administration to young GK rats. Aged Wistar rats had an impairment of some parameters, whereas MG administration caused a phenotype similar to young GK rats, including oxidative stress, impaired apoptotic and angiogenic markers, and structural lesions. MG accumulation specifically impaired several of the renal disease markers progressively observed in diabetic rats, and thus, it contributes to the progression of diabetic nephropathy.

  13. Advanced glycation end products in human cancer tissues: detection of Nepsilon-(carboxymethyl)lysine and argpyrimidine.

    PubMed

    van Heijst, Jeroen W J; Niessen, Hans W M; Hoekman, Klaas; Schalkwijk, Casper G

    2005-06-01

    Tumors are generally characterized by an increased glucose uptake and a high rate of glycolysis. Since one consequence of an elevated glycolysis is the nonenzymatic glycation of proteins, we studied the presence of advanced glycation end products (AGEs) in human cancer tissues. We detected the presence of the AGEs N(epsilon)-(carboxymethyl)lysine (CML) and argpyrimidine in several human tumors using specific antibodies. Because AGEs have been associated with the etiology of a variety of different diseases, these results suggest that CML and argpyrimidine could be implicated in the biology of human cancer.

  14. Inhibition of the formation of advanced glycation end products by thymoquinone.

    PubMed

    Losso, Jack N; Bawadi, Hiba A; Chintalapati, Madhavi

    2011-09-01

    The inhibitory activity of thymoquinone, a major quinone from black seeds (Nigella sativa) against the formation of advanced glycation end products was studied using the hemoglobin-δ-gluconolactone, human serum albumin-glucose, and the N-acetyl-glycyl-lysine methyl ester-ribose assays. A comparison was made with the inhibitory activity of aminoguanidine. The cytotoxicity of thymoquinone was studied by the release of lactate dehydrogenase from platelets and the levels of plasma thiols. At 20μM, thymoquinone inhibited 39% of hemoglobin glycation, 82% of post-Amadori glycation products, reduced methyglyoxal-mediated human serum albumin glycation by 68%, inhibited 78% of late glycation end products. Aminoguanidine at 10mM was less effective than thymoquinone. The IC50 for thymoquinone and aminoguanidine were 7.2μM and 1.25mM, respectively. Thymoquinone at 20-50μM was not toxic to platelet lactate dehydrogenase and plasma thiols. The potential of thymoquinone in food applications is discussed.

  15. Advanced Glycation End Products in Extracellular Matrix Proteins Contribute to the Failure of Sensory Nerve Regeneration in Diabetes

    PubMed Central

    Duran-Jimenez, Beatriz; Dobler, Darin; Moffatt, Sarah; Rabbani, Naila; Streuli, Charles H.; Thornalley, Paul J.; Tomlinson, David R.; Gardiner, Natalie J.

    2009-01-01

    OBJECTIVE The goal of this study was to characterize glycation adducts formed in both in vivo extracellular matrix (ECM) proteins of endoneurium from streptozotocin (STZ)-induced diabetic rats and in vitro by glycation of laminin and fibronectin with methylglyoxal and glucose. We also investigated the impact of advanced glycation end product (AGE) residue content of ECM on neurite outgrowth from sensory neurons. RESEARCH DESIGN AND METHODS Glycation, oxidation, and nitration adducts of ECM proteins extracted from the endoneurium of control and STZ-induced diabetic rat sciatic nerve (3–24 weeks post-STZ) and of laminin and fibronectin that had been glycated using glucose or methylglyoxal were examined by liquid chromatography with tandem mass spectrometry. Methylglyoxal-glycated or unmodified ECM proteins were used as substrata for dissociated rat sensory neurons as in vitro models of regeneration. RESULTS STZ-induced diabetes produced a significant increase in early glycation Nε-fructosyl-lysine and AGE residue contents of endoneurial ECM. Glycation of laminin and fibronectin by methylglyoxal and glucose increased glycation adduct residue contents with methylglyoxal-derived hydroimidazolone and Nε-fructosyl-lysine, respectively, of greatest quantitative importance. Glycation of laminin caused a significant decrease in both neurotrophin-stimulated and preconditioned sensory neurite outgrowth. This decrease was prevented by aminoguanidine. Glycation of fibronectin also decreased preconditioned neurite outgrowth, which was prevented by aminoguanidine and nerve growth factor. CONCLUSIONS Early glycation and AGE residue content of endoneurial ECM proteins increase markedly in STZ-induced diabetes. Glycation of laminin and fibronectin causes a reduction in neurotrophin-stimulated neurite outgrowth and preconditioned neurite outgrowth. This may provide a mechanism for the failure of collateral sprouting and axonal regeneration in diabetic neuropathy. PMID:19720799

  16. Linolenic acid prevents early and advanced glycation end-products (AGEs) modification of albumin.

    PubMed

    Prasanna, Govindarajan; Saraswathi, N T

    2017-02-01

    In this study, we report the protective effects of linolenic acid towards the formation of early (HbA1c) and advanced glycation end-products (AGEs) based on fluorescence, circular dichroism, confocal microscopy and molecular interaction studies. Linolenic acid was found to be a potent inhibitor of AGEs formed by both glucose and fructose. The HbA1c (early glycation product) level was found to be reduced to 7.4% when compared to glycated control (8.4%). Similarly, linolenic acid also inhibited the methylglyoxal mediated AGEs formation. Circular dichroism spectroscopy studies suggested that the protective effect of linolenic acid for the helical structure of albumin. The molecular interaction studies showed that linolenic acid interacts with arginine residues of albumin with high affinity. Results suggested linolenic acid to be a potent antiglycation compound and also it could be a better lead compound for AGE inhibition.

  17. Sesamin Ameliorates Advanced Glycation End Products-Induced Pancreatic β-Cell Dysfunction and Apoptosis.

    PubMed

    Kong, Xiang; Wang, Guo-Dong; Ma, Ming-Zhe; Deng, Ru-Yuan; Guo, Li-Qun; Zhang, Jun-Xiu; Yang, Jie-Ren; Su, Qing

    2015-06-09

    Advanced glycation end products (AGEs), the direct modulators of β-cells, have been shown to cause insulin-producing β-cell dysfunction and apoptosis through increase of intracellular reactive oxygen species (ROS) production. Sesamin has been demonstrated to possess antioxidative activity. This study was designed to investigate whether sesamin protects against AGEs-evoked β-cell damage via its antioxidant property. The effects of sesamin were examined in C57BL/6J mice and MIN6 cell line. In in vivo studies, mice were intraperitoneally injected with AGEs (120 mg/kg) and orally treated with sesamin (160 mg/kg) for four weeks. Intraperitoneal glucose tolerance and insulin releasing tests were performed. Insulin content, ROS generation and β-cell apoptosis in pancreatic islets were also measured. In in vitro studies, MIN6 cells were pretreated with sesamin (50 or 100 μM) and then exposed to AGEs (200 mg/L) for 24 h. Insulin secretion, β-cell death, ROS production as well as expression and activity of NADPH oxidase were determined. Sesamin treatment obviously ameliorated AGE-induced β-cell dysfunction and apoptosis both in vivo and in vitro. These effects were associated with decreased ROS production, down-regulated expression of p67(phox) and p22(phox), and reduced NADPH oxidase activity. These results suggest that sesamin protects β-cells from damage caused by AGEs through suppressing NADPH oxidase-mediated oxidative stress.

  18. Sesamin Ameliorates Advanced Glycation End Products-Induced Pancreatic β-Cell Dysfunction and Apoptosis

    PubMed Central

    Kong, Xiang; Wang, Guo-Dong; Ma, Ming-Zhe; Deng, Ru-Yuan; Guo, Li-Qun; Zhang, Jun-Xiu; Yang, Jie-Ren; Su, Qing

    2015-01-01

    Advanced glycation end products (AGEs), the direct modulators of β-cells, have been shown to cause insulin-producing β-cell dysfunction and apoptosis through increase of intracellular reactive oxygen species (ROS) production. Sesamin has been demonstrated to possess antioxidative activity. This study was designed to investigate whether sesamin protects against AGEs-evoked β-cell damage via its antioxidant property. The effects of sesamin were examined in C57BL/6J mice and MIN6 cell line. In in vivo studies, mice were intraperitoneally injected with AGEs (120 mg/kg) and orally treated with sesamin (160 mg/kg) for four weeks. Intraperitoneal glucose tolerance and insulin releasing tests were performed. Insulin content, ROS generation and β-cell apoptosis in pancreatic islets were also measured. In in vitro studies, MIN6 cells were pretreated with sesamin (50 or 100 μM) and then exposed to AGEs (200 mg/L) for 24 h. Insulin secretion, β-cell death, ROS production as well as expression and activity of NADPH oxidase were determined. Sesamin treatment obviously ameliorated AGE-induced β-cell dysfunction and apoptosis both in vivo and in vitro. These effects were associated with decreased ROS production, down-regulated expression of p67phox and p22phox, and reduced NADPH oxidase activity. These results suggest that sesamin protects β-cells from damage caused by AGEs through suppressing NADPH oxidase-mediated oxidative stress. PMID:26066015

  19. Therapeutic interventions for Advanced Glycation-End Products and its Receptor-Mediated Cardiovascular Disease.

    PubMed

    Prasad, Kailash; Tiwari, Shuchita

    2016-10-06

    Advanced glycation end products (AGEs) are heterogeneous group of molecules formed from non-enzymatic reaction of reducing sugars with amino group of proteins, lipids, and nucleic acid. Interaction of AGEs with its cell-bound receptor (RAGE) results in generation of oxygen radicals, nuclear factor kappa-β, pro-inflammatory cytokines and cell adhesion molecules, and is involved in the pathophysiology of cardiovascular diseases (CVD). Circulating soluble forms of RAGE (sRAGE) and endo-secretory RAGE (esRAGE) compete with RAGE for ligand binding and function as a decoy. This paper describes the endogenous and exogenous (high dietary AGEs, cooking food under high dry heat, elevated pH, and long period) sources of AGEs. AGE-RAGE-mediated CVD includes atherosclerosis, coronary artery disease, carotid artery disease, hypertension, peripheral vascular diseases, heart failure, cardiomyopathy, and microangiopathy. The therapeutic intervention with reduction in AGEs and RAGE, and elevation in sRAGE has been reported for the treatment of AGE-RAGE-mediated CVD. Reduction in levels of AGEs can be achieved by reduction in consumption of food containing low amount of AGEs, cooking food at low temperature, moist heat, and shorter duration. AGE formation can be reduced with drugs, vitamins and stoppage of cigarette smoking. Statins, telmisartan, and curcumin have been used for suppression of RAGE. Statins, ACE-inhibitors, Rosiglitazone and vitamin D have been used to increase levels of sRAGE. Finally exogenous administration of sRAGE can be helpful in amelioration of CVD. In conclusion, AGE-RAGE-mediated CVD could be attenuated with reduction in consumption of AGEs, suppression of RAGE and elevation of sRAGE.

  20. Decrease in fluorescence lifetime by glycation of collagen and its application in determining advanced glycation end-products in human dentin

    PubMed Central

    Fukushima, Shuichiro; Shimizu, Masato; Miura, Jiro; Matsuda, Yusuke; Kubo, Mizuho; Hashimoto, Mamoru; Aoki, Takuya; Takeshige, Fumio; Araki, Tsutomu

    2015-01-01

    Advanced Glycation End-products (AGEs) are produced by the Maillard reaction, which causes cross-linking of collagen and results in changes in the mechanical properties of collagen tissues. Several types of AGE fluoresce, and measurement of this fluorescence is effective for determining the presence of AGEs. Because fluorescence intensity by steady-state fluorometry is affected by sample surface condition and light source, we focused on fluorescence lifetime measurement (FLM). We found that fluorescence lifetime of collagen gel decreased with glycation progress. In vivo application of FLM for determination of AGEs was confirmed in human dentin. PMID:26137384

  1. Inhibition of advanced glycation end-product formation on eye lens protein by rutin.

    PubMed

    Muthenna, P; Akileshwari, C; Saraswat, Megha; Bhanuprakash Reddy, G

    2012-04-01

    Formation of advanced glycation end products (AGE) plays a key role in the several pathophysiologies associated with ageing and diabetes, such as arthritis, atherosclerosis, chronic renal insufficiency, Alzheimer's disease, nephropathy, neuropathy and cataract. This raises the possibility of inhibition of AGE formation as one of the approaches to prevent or arrest the progression of diabetic complications. Previously, we have reported that some common dietary sources such as fruits, vegetables, herbs and spices have the potential to inhibit AGE formation. Flavonoids are abundantly found in fruits, vegetables, herbs and spices, and rutin is one of the commonly found dietary flavonols. In the present study, we have demonstrated the antiglycating potential and mechanism of action of rutin using goat eye lens proteins as model proteins. Under in vitro conditions, rutin inhibited glycation as assessed by SDS-PAGE, AGE-fluorescence, boronate affinity chromatography and immunodetection of specific AGE. Further, we provided insight into the mechanism of inhibition of protein glycation that rutin not only scavenges free-radicals directly but also chelates the metal ions by forming complexes with them and thereby partly inhibiting post-Amadori formation. These findings indicate the potential of rutin to prevent and/or inhibit protein glycation and the prospects for controlling AGE-mediated diabetic pathological conditions in vivo.

  2. Acetoacetate promotes the formation of fluorescent advanced glycation end products (AGEs).

    PubMed

    Bohlooli, Mousa; Ghaffari-Moghaddam, Mansour; Khajeh, Mostafa; Aghashiri, Zohre; Sheibani, Nader; Moosavi-Movahedi, Ali Akbar

    2016-12-01

    Acetoacetate (AA) is an important ketone body, which produces reactive oxygen species (ROS). Advanced glycation end products (AGEs) are defined as final products of glycation process whose production is influenced by the levels of ROS. The accumulation of AGEs in the body contributes to pathogenesis of many diseases including complications of diabetes, and Alzheimer's and Parkinson's disease. Here, we evaluated the impact of AA on production of AGEs upon incubation of human serum albumin (HSA) with glucose. The effect of AA on the AGEs formation of HSA was studied under physiological conditions after incubation with glucose for 35 days. The physical techniques including circular dichroism (CD) and fluorescence spectroscopy were used to assess the impact of AA on formation and structural changes of glycated HSA (GHSA). Our results indicated that the secondary and tertiary structural changes of GHSA were increased in the presence of AA. The fluorescence intensity measurements of AGEs also showed an increase in AGEs formation. Acetoacetate has an activator effect in formation of AGEs through ROS production. The presence of AA may result in enhanced glycation in the presence of glucose and severity of complications associated with accumulation of AGEs.

  3. Advanced glycation end products induce differential structural modifications and fibrillation of albumin

    NASA Astrophysics Data System (ADS)

    Awasthi, Saurabh; Sankaranarayanan, Kamatchi; Saraswathi, N. T.

    2016-06-01

    Glycation induced amyloid fibrillation is fundamental to the development of many neurodegenerative and cardiovascular complications. Excessive non-enzymatic glycation in conditions such as hyperglycaemia results in the increased accumulation of advanced glycation end products (AGEs). AGEs are highly reactive pro-oxidants, which can lead to the activation of inflammatory pathways and development of oxidative stress. Recently, the effect of non-enzymatic glycation on protein structure has been the major research area, but the role of specific AGEs in such structural alteration and induction of fibrillation remains undefined. In this study, we determined the specific AGEs mediated structural modifications in albumin mainly considering carboxymethyllysine (CML), carboxyethyllysine (CEL), and argpyrimidine (Arg-P) which are the major AGEs formed in the body. We studied the secondary structural changes based on circular dichroism (CD) and spectroscopic analysis. The AGEs induced fibrillation was determined by Congo red binding and examination of scanning and transmission electron micrographs. The amyloidogenic regions in the sequence of BSA were determined using FoldAmyloid. It was observed that CEL modification of BSA leads to the development of fibrillar structures, which was evident from both secondary structure changes and TEM analysis.

  4. Hormetic modulation of hepatic insulin sensitivity by advanced glycation end products.

    PubMed

    Fabre, Nelly T; Thieme, Karina; Silva, Karolline S; Catanozi, Sérgio; Cavaleiro, Ana Mercedes; Pinto, Danilo A C; Okamoto, Maristela M; Morais, Mychel Raony P T; Falquetto, Bárbara; Zorn, Telma M; Machado, Ubiratan F; Passarelli, Marisa; Correa-Giannella, Maria Lúcia

    2017-05-15

    Because of the paucity of information regarding metabolic effects of advanced glycation end products (AGEs) on liver, we evaluated effects of AGEs chronic administration in (1) insulin sensitivity; (2) hepatic expression of genes involved in AGEs, glucose and fat metabolism, oxidative stress and inflammation and; (3) hepatic morphology and glycogen content. Rats received intraperitoneally albumin modified (AlbAGE) or not by advanced glycation for 12 weeks. AlbAGE induced whole-body insulin resistance concomitantly with increased hepatic insulin sensitivity, evidenced by activation of AKT, inactivation of GSK3, increased hepatic glycogen content, and decreased expression of gluconeogenesis genes. Additionally there was reduction in hepatic fat content, in expression of lipogenic, pro-inflamatory and pro-oxidative genes and increase in reactive oxygen species and in nuclear expression of NRF2, a transcription factor essential to cytoprotective response. Although considered toxic, AGEs become protective when administered chronically, stimulating AKT signaling, which is involved in cellular defense and insulin sensitivity.

  5. Advanced glycation end-products and receptor for advanced glycation end-products expression in patients with idiopathic pulmonary fibrosis and NSIP.

    PubMed

    Kyung, Sun Young; Byun, Kyung Hee; Yoon, Jin Young; Kim, Yu Jin; Lee, Sang Pyo; Park, Jeong-Woong; Lee, Bong Hee; Park, Jong Sook; Jang, An Soo; Park, Choon Sik; Jeong, Sung Hwan

    2014-01-01

    Advanced glycation end products (AGEs) are associated with the pathogenesis of various diseases. AGEs induce excess accumulation of extracellular matrix and expression of profibrotic cytokines. In addition, studies on receptor for advanced glycation end products (RAGE) have shown that the ligand-RAGE interaction activates several intracellular signaling cascades associated with several fibrotic diseases. We investigated the expression of AGEs and RAGE in samples from patients with idiopathic pulmonary fibrosis (IPF) and non-specific interstitial pneumonia (NSIP). Lung tissues and plasma samples from patients with IPF (n=10), NSIP (n=10), and control subjects (n=10) were obtained. Expression of AGEs and RAGE was determined by immunofluorescence assay of lung tissue. Circulating AGEs were measured by Western blot and enzyme-linked immunosorbent assay. Lungs with IPF showed strong expression for both AGEs and RAGE compared to that in NSIP and controls. However, no difference in AGE or RAGE expression was observed in lungs with NSIP compared to that in the controls. Levels of circulating AGEs also increased significantly in lungs of patients with IPF compared to those with NSIP and normal control. Increased AGE-RAGE interaction may play an important role in the pathogenesis of IPF.

  6. Advanced glycation end-products and receptor for advanced glycation end-products expression in patients with idiopathic pulmonary fibrosis and NSIP

    PubMed Central

    Kyung, Sun Young; Byun, Kyung Hee; Yoon, Jin Young; Kim, Yu Jin; Lee, Sang Pyo; Park, Jeong-Woong; Lee, Bong Hee; Park, Jong Sook; Jang, An Soo; Park, Choon Sik; Jeong, Sung Hwan

    2014-01-01

    Advanced glycation end products (AGEs) are associated with the pathogenesis of various diseases. AGEs induce excess accumulation of extracellular matrix and expression of profibrotic cytokines. In addition, studies on receptor for advanced glycation end products (RAGE) have shown that the ligand-RAGE interaction activates several intracellular signaling cascades associated with several fibrotic diseases. We investigated the expression of AGEs and RAGE in samples from patients with idiopathic pulmonary fibrosis (IPF) and non-specific interstitial pneumonia (NSIP). Lung tissues and plasma samples from patients with IPF (n=10), NSIP (n=10), and control subjects (n=10) were obtained. Expression of AGEs and RAGE was determined by immunofluorescence assay of lung tissue. Circulating AGEs were measured by Western blot and enzyme-linked immunosorbent assay. Lungs with IPF showed strong expression for both AGEs and RAGE compared to that in NSIP and controls. However, no difference in AGE or RAGE expression was observed in lungs with NSIP compared to that in the controls. Levels of circulating AGEs also increased significantly in lungs of patients with IPF compared to those with NSIP and normal control. Increased AGE-RAGE interaction may play an important role in the pathogenesis of IPF. PMID:24427342

  7. Beneficial effects of metformin and irbesartan on advanced glycation end products (AGEs)-RAGE-induced proximal tubular cell injury.

    PubMed

    Ishibashi, Yuji; Matsui, Takanori; Takeuchi, Masayoshi; Yamagishi, Sho-ichi

    2012-03-01

    Advanced glycation end products (AGEs) and their receptor (RAGE) axis contributes to diabetic nephropathy. An oral hypoglycemic agent, metformin may have a potential effect on the inhibition of glycation reactions. Further, since a pathophysiological crosstalk between renin-angiotensin system (RAS) and AGEs-RAGE axis is involved in diabetic nephropathy, it is conceivable that metformin and irbesartan additively could protect against the AGEs-RAGE-induced tubular cell injury. In this study, we addressed the issues. Metformin dose-dependently inhibited the formation of AGEs modification of bovine serum albumin (BSA). Compared with AGEs-modified BSA prepared without metformin (AGEs-MF0), those prepared in the presence of 30 mM or 100 mM metformin (AGEs-MF30 or AGEs-MF100) significantly reduced RAGE mRNA level, reactive oxygen species (ROS) generation, apoptosis, monocyte chemoattractant protein-1 and transforming growth factor-β mRNA level in tubular cells. Irbesartan further inhibited the harmful effects of AGEs-MF0 or AGEs-MF30 on tubular cells. Our present study suggests that combination therapy with metformin and irbesartan may have therapeutic potential in diabetic nephropathy; it could play a protective role against tubular injury in diabetes not only by inhibiting AGEs formation, but also by attenuating the deleterious effects of AGEs via down-regulating RAGE expression and subsequently suppressing ROS generation.

  8. Genomic damage in end-stage renal failure: potential involvement of advanced glycation end products and carbonyl stress.

    PubMed

    Stopper, Helga; Schupp, Nicole; Bahner, Udo; Sebekova, Katarina; Klassen, Andre; Heidland, August

    2004-09-01

    In patients with chronic renal failure, genomic damage has been shown by numerous biomarkers, such as micronuclei frequency and comet assay (single-cell gel electrophoresis) in peripheral lymphocytes, 8-hydroxy 2'-deoxyguanosine (8-OH-dG) content in leukocytes, mitochondrial DNA deletions in skeletal muscle tissue and hair follicles, as well as in DNA repair mechanisms in freshly isolated lymphocytes after ultraviolet light exposure. In the pathogenesis of DNA damage--besides genetic influences, enhanced reactive oxygen species (ROS), and lipid peroxidation-the genotoxic potential of advanced glycation end products (AGEs) and reactive carbonyl compounds deserve special attention. In fact, reactions of glucose with DNA can lead to mutagenic DNA AGEs. In vitro, incubation of tubulus cells with various AGEs and methylglyoxal induces DNA damage, which is suppressed by antioxidants. This underlines the role played by oxidative stress in DNA damage.

  9. Inflammation-induced chondrocyte hypertrophy is driven by receptor for advanced glycation end products.

    PubMed

    Cecil, Denise L; Johnson, Kristen; Rediske, John; Lotz, Martin; Schmidt, Ann Marie; Terkeltaub, Robert

    2005-12-15

    The multiligand receptor for advanced glycation end products (RAGE) mediates certain chronic vascular and neurologic degenerative diseases accompanied by low-grade inflammation. RAGE ligands include S100/calgranulins, a class of low-molecular-mass, calcium-binding polypeptides, several of which are chondrocyte expressed. Here, we tested the hypothesis that S100A11 and RAGE signaling modulate osteoarthritis (OA) pathogenesis by regulating a shift in chondrocyte differentiation to hypertrophy. We analyzed human cartilages and cultured human articular chondrocytes, and used recombinant human S100A11, soluble RAGE, and previously characterized RAGE-specific blocking Abs. Normal human knee cartilages demonstrated constitutive RAGE and S100A11 expression, and RAGE and S100A11 expression were up-regulated in OA cartilages studied by immunohistochemistry. CXCL8 and TNF-alpha induced S100A11 expression and release in cultured chondrocytes. Moreover, S100A11 induced cell size increase and expression of type X collagen consistent with chondrocyte hypertrophy in vitro. CXCL8-induced, IL-8-induced, and TNF-alpha-induced but not retinoic acid-induced chondrocyte hypertrophy were suppressed by treatment with soluble RAGE or RAGE-specific blocking Abs. Last, via transfection of dominant-negative RAGE and dominant-negative MAPK kinase 3, we demonstrated that S100A11-induced chondrocyte type X collagen expression was dependent on RAGE-mediated p38 MAPK pathway activation. We conclude that up-regulated chondrocyte expression of the RAGE ligand S100A11 in OA cartilage, and RAGE signaling through the p38 MAPK pathway, promote inflammation-associated chondrocyte hypertrophy. RAGE signaling thereby has the potential to contribute to the progression of OA.

  10. Do Advanced Glycation End Products and Its Receptor Play a Role in Pathophysiology of Hypertension?

    PubMed

    Prasad, Kailash; Mishra, Manish

    2017-03-01

    There is a close relationship between arterial stiffness and blood pressure. The studies suggest that the advanced glycation end products (AGEs) and its cell receptor (RAGE) are involved in the arterial stiffness in two ways: changes in arterial structure and vascular function. Plasma levels of AGEs and expression of RAGE are elevated, while the levels of soluble RAGE (sRAGE) and endogenous secretory RAGE (esRAGE) are lowered in patients with hypertension (HTN). There is a positive correlation between plasma levels of AGEs and arterial stiffness, and an inverse association between arterial stiffness/HTN, and serum levels of sRAGE and esRAGE. Various measures can reduce the levels of AGEs and expression of RAGE, and elevate sRAGE. Arterial stiffness and blood pressure could be reduced by lowering the serum levels of AGEs, and increasing the levels of sRAGE. Levels of AGEs can be lowered by reducing the consumption of AGE-rich diet, short duration of cooking in moist heat at low temperature, and cessation of cigarette smoking. Drugs such as aminoguanidine, vitamins, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor blockers, statins, and metformin inhibit AGE formation. Alagebrium, an AGE breakers reduces levels of AGEs. Clinical trials with some drugs tend to reduce stiffness. Systemic administration of sRAGE has beneficial effect in animal studies. In conclusion, AGE-RAGE axis is involved in arterial stiffness and HTN. The studies suggest that inhibition of AGEs formation, reduction of AGE consumption, blockade of AGE-RAGE interaction, suppression of RAGE expression, and exogenous administration of sRAGE may be novel therapeutic strategies for treatment of arterial stiffness and HTN.

  11. ERM protein moesin is phosphorylated by advanced glycation end products and modulates endothelial permeability.

    PubMed

    Guo, Xiaohua; Wang, Lingjun; Chen, Bo; Li, Qiang; Wang, Jiping; Zhao, Ming; Wu, Wei; Zhu, Ping; Huang, Xuliang; Huang, Qiaobing

    2009-07-01

    Advanced glycation end products (AGEs) accumulated in different pathological conditions have the potent capacity to alter cellular properties that include endothelial structural and functional regulations. The disruption of endothelial barrier integrity may contribute to AGE-induced microangiopathy and macrovasculopathy. Previous studies have shown that AGEs induced the rearrangement of actin and subsequent hyperpermeability in endothelial cells (ECs). However, the mechanisms involved in this AGE-evoked EC malfunction are not well understood. This study directly evaluated the involvement of moesin phosphorylation in AGE-induced alterations and the effects of the RhoA and p38 MAPK pathways on this process. Using immortalized human dermal microvascular ECs (HMVECs), we first confirmed that the ezrin/radixin/moesin (ERM) protein moesin is required in AGE-induced F-actin rearrangement and hyperpermeability responses in ECs by knockdown of moesin protein expression with small interfering RNA. We then detected AGE-induced moesin phosphorylation by Western blot analysis. The mechanisms involved in moesin phosphorylation were analyzed by blocking AGE receptor binding and inhibiting Rho and MAPK pathways. AGE-treated HMVECs exhibited time- and dose-dependent increases in the Thr(558) phosphorylation of moesin. The increased moesin phosphorylation was attenuated by preadministrations of AGE receptor antibody, Rho kinase (ROCK), or p38 inhibitor. Suppression of p38 activation via the expression of dominant negative mutants with Ad.MKK6b or Ad.p38alpha also decreased moesin phosphorylation. The activation of the p38 pathway by transfection of HMVECs with an adenoviral construct of dominant active MKK6b resulted in moesin phosphorylation. These results suggest a critical role of moesin phosphorylation in AGE-induced EC functional and morphological regulations. Activation of the ROCK and p38 pathways is required in moesin phosphorylation.

  12. Advanced Glycation End Products, Inflammation, and Chronic Metabolic Diseases: Links in a Chain?

    PubMed

    Davis, Kathleen E; Prasad, Chandan; Vijayagopal, Parakat; Juma, Shanil; Imrhan, Victorine

    2016-01-01

    Advanced glycation end products (AGEs) are a diverse group of compounds produced when reducing sugars react with proteins or other compounds to form glycosylated molecules. AGEs may form endogenously, and glycation of molecules may negatively affect their function. AGEs may also be consumed in food form with dietary AGEs reported to be particularly high in foods treated with high heat: baked, broiled, grilled, and fried foods. Whether dietary AGEs are absorbed in significant quantities and whether they are harmful if absorbed is a question under current debate. The American Diabetes Association makes no recommendation regarding avoidance of these foods, but many researchers are concerned that they may be pro-inflammatory and way worsen cardiac function, kidney function, diabetes and its complications and may even contribute to obesity.

  13. Advanced glycation end-products (AGEs): involvement in aging and in neurodegenerative diseases.

    PubMed

    Grillo, M A; Colombatto, S

    2008-06-01

    Advanced glycation end-products (AGEs) are formed from the so-called Amadori products by rearrangement followed by other reactions giving rise to compounds bound irreversibly. The structure of some of them is shown and the mechanism of formation is described. Several AGE binding molecules (Receptors for AGE, RAGE) are known and it is thought that many of the effects caused by AGEs are mediated by RAGE. Some of these were shown to be toxic, and called TAGE. The mechanism of detoxification of glyoxal and methylglyoxal by the glyoxalase system is described and also the possibility to eliminate glycated proteins by deglycation enzymes. Compounds able to inhibit AGEs formation are also taken into consideration.

  14. Skin autofluorescence, a non-invasive marker of advanced glycation end products: clinical relevance and limitations.

    PubMed

    Da Moura Semedo, Cidila; Webb, M'Balu; Waller, Helen; Khunti, Kamlesh; Davies, Melanie

    2017-01-31

    Advanced glycation end products (AGEs) are protein-bound compounds derived from glycaemic and oxidative stress that contain fluorescent properties, which can be non-invasively measured as skin autofluorescence (SAF) by the AGE Reader. SAF has been demonstrated to be a biomarker of cumulative skin AGEs and potentially may be a better predictor for the development of chronic complications and mortality in diabetes than glycated haemoglobin A1c. However, there are several confounding factors that should be assessed prior to its broader application: these include presence of other fluorescent compounds in the skin that might be measured (eg, fluorophores), skin pigmentation and use of skin creams. The aim of this article is to provide a theoretical background of this newly developed method, evaluate its clinical relevance and discuss the potential confounding factors that need further analysis.

  15. Pathologic role of dietary advanced glycation end products in cardiometabolic disorders, and therapeutic intervention.

    PubMed

    Yamagishi, Sho-Ichi; Matsui, Takanori

    2016-02-01

    Reactive derivatives from nonenzymatic glucose-protein condensation reactions, as well as lipids and nucleic acids exposed to reducing sugars, form a heterogeneous group of irreversible adducts called AGEs (advanced glycation end products). The glycation process begins with the conversion of reversible Schiff base adducts to more stable, covalently bound Amadori rearrangement products. Over the course of days to weeks, these Amadori products undergo further rearrangement and condensation reactions to form irreversibly cross-linked macroprotein derivatives known as AGEs. The formation and accumulation of AGEs have been known to progress in a physiological aging process and at an accelerated rate under hyperglycemic and oxidative stress conditions. There is growing evidence that AGEs play a pathologic role in numerous disorders. Indeed, glycation and/or cross-linking modification of circulating or organic matrix proteins by AGEs the senescence of moieties and deteriorate their physiological function and structural integrity in multiple organ systems. Moreover, AGEs elicit oxidative stress and inflammatory reactions through the interaction with the receptor for advanced glycation products in a variety of cells, thereby contributing to the development and progression of various aging- or diabetes-related disorders, such as cardiovascular disease, chronic kidney disease, insulin resistance, and Alzheimer's disease. Recently, diet has been recognized as a major environmental source of AGEs that could cause proinflammatory reactions and organ damage in vivo. Therefore, this review summarizes the pathophysiological role of dietary AGEs in health and disease, especially focusing on cardiometabolic disorders. We also discuss the potential utility in targeting exogenously derived AGEs for therapeutic intervention.

  16. Advanced glycation end-products: Mechanics of aged collagen from molecule to tissue.

    PubMed

    Gautieri, Alfonso; Passini, Fabian S; Silván, Unai; Guizar-Sicairos, Manuel; Carimati, Giulia; Volpi, Piero; Moretti, Matteo; Schoenhuber, Herbert; Redaelli, Alberto; Berli, Martin; Snedeker, Jess G

    2017-05-01

    Concurrent with a progressive loss of regenerative capacity, connective tissue aging is characterized by a progressive accumulation of Advanced Glycation End-products (AGEs). Besides being part of the typical aging process, type II diabetics are particularly affected by AGE accumulation due to abnormally high levels of systemic glucose that increases the glycation rate of long-lived proteins such as collagen. Although AGEs are associated with a wide range of clinical disorders, the mechanisms by which AGEs contribute to connective tissue disease in aging and diabetes are still poorly understood. The present study harnesses advanced multiscale imaging techniques to characterize a widely employed in vitro model of ribose induced collagen aging and further benchmarks these data against experiments on native human tissues from donors of different age. These efforts yield unprecedented insight into the mechanical changes in collagen tissues across hierarchical scales from molecular, to fiber, to tissue-levels. We observed a linear increase in molecular spacing (from 1.45nm to 1.5nm) and a decrease in the D-period length (from 67.5nm to 67.1nm) in aged tissues, both using the ribose model of in vitro glycation and in native human probes. Multiscale mechanical analysis of in vitro glycated tendons strongly suggests that AGEs reduce tissue viscoelasticity by severely limiting fiber-fiber and fibril-fibril sliding. This study lays an important foundation for interpreting the functional and biological effects of AGEs in collagen connective tissues, by exploiting experimental models of AGEs crosslinking and benchmarking them for the first time against endogenous AGEs in native tissue.

  17. Skin advanced glycation end-products evaluation in infants according to the type of feeding and mother’s smoking habits

    PubMed Central

    Federico, Giovanni; Gori, Martina; Randazzo, Emioli; Vierucci, Francesco

    2016-01-01

    Objectives: This study was conducted to assess whether formula-fed infants had increased skin advanced glycation end-products compared with breastfed ones. We also evaluated the effect of maternal smoke during pregnancy and lactation on infant skin advanced glycation end-products accumulation. Methods: Advanced glycation end-product–linked skin autofluorescence was measured in 101 infants. Results: In infants born from non-smoking mothers, advanced glycation end-products were higher in formula-fed subjects than in breastfed subjects (0.80 (0.65–0.90) vs 1.00 (0.85–1.05), p < 0.001). Advanced glycation end-products in breastfed infants from smoking mothers were higher than in those from non-smoking mothers (0.80 (0.65–0.90) vs 1.00 (0.90–1.17), p = 0.009). Conclusion: Formula-fed infants had increased amounts of advanced glycation end-products compared with the breastfed ones, confirming that breast milk represents the best food for infants. Breastfed infants from mothers smoking during pregnancy and lactation had increased skin advanced glycation end-products, suggesting that smoke-related advanced glycation end-products transfer throughout breast milk. Moreover, advanced glycation end-products may already increase during gestation, possibly affecting fetal development. Thus, we reinforced that smoking must be stopped during pregnancy and lactation. PMID:28210490

  18. Glycative Stress and Its Defense Machinery Glyoxalase 1 in Renal Pathogenesis

    PubMed Central

    Hirakawa, Yosuke; Inagi, Reiko

    2017-01-01

    Chronic kidney disease is a major public health problem around the world. Because the kidney plays a role in reducing glycative stress, renal dysfunction results in increased glycative stress. In turn, glycative stress, especially that due to advanced glycated end products (AGEs) and their precursors such as reactive carbonyl compounds, exacerbates chronic kidney disease and is related to premature aging in chronic kidney disease, whether caused by diabetes mellitus or otherwise. Factors which hinder a sufficient reduction in glycative stress include the inhibition of anti-glycation enzymes (e.g., GLO-1), as well as pathogenically activated endoplasmic reticulum (ER) stress and hypoxia in the kidney. Promising strategies aimed at halting the vicious cycle between chronic kidney disease and increases in glycative stress include the suppression of AGE accumulation in the body and the enhancement of GLO-1 to strengthen the host defense machinery against glycative stress. PMID:28106734

  19. Hydroxy methoxy benzaldehyde from Sesbania grandilfora inhibits the advanced glycation end products (AGEs)-mediated fibrillation in hemoglobin.

    PubMed

    Prasanna, G; Hari, N; Saraswathi, N T

    2017-03-20

    The present study was aimed to identify the active anti-glycation constituent from the leaves of Sesbania grandiflora. Characterization of the active constituent resulted in the identification of hydroxy methoxy benzaldehyde (HMB). The potential of HMB as anti-glycation lead was analyzed by fluorescence spectroscopy, fluorescence microscopy, scanning electron microscopy (SEM) and molecular interaction studies. Our results suggested that HMB inhibited formation of early (HbA1c) and advanced glycation end products (AGEs). The amyloid-like fibrillation in hemoglobin was also inhibited by HMB. SEM images indicated the protective effect against the formation of acanthocytes. Molecular docking studies showed that HMB was interacting with hemoglobin through hydrogen bonds with Arg141, Tyr140, and Thr137. Our findings suggest that HMB could be a better anti-glycation lead molecule towards novel AGEs inhibitors.

  20. Inhibition of advanced glycation endproduct formation by acetaldehyde: role in the cardioprotective effect of ethanol.

    PubMed

    Al-Abed, Y; Mitsuhashi, T; Li, H; Lawson, J A; FitzGerald, G A; Founds, H; Donnelly, T; Cerami, A; Ulrich, P; Bucala, R

    1999-03-02

    Epidemiological studies suggest that there is a beneficial effect of moderate ethanol consumption on the incidence of cardiovascular disease. Ethanol is metabolized to acetaldehyde, a two-carbon carbonyl compound that can react with nucleophiles to form covalent addition products. We have identified a biochemical modification produced by the reaction of acetaldehyde with protein-bound Amadori products. Amadori products typically arise from the nonenzymatic addition of reducing sugars (such as glucose) to protein amino groups and are the precursors to irreversibly bound, crosslinking moieties called advanced glycation endproducts, or AGEs. AGEs accumulate over time on plasma lipoproteins and vascular wall components and play an important role in the development of diabetes- and age-related cardiovascular disease. The attachment of acetaldehyde to a model Amadori product produces a chemically stabilized complex that cannot rearrange and progress to AGE formation. We tested the role of this reaction in preventing AGE formation in vivo by administering ethanol to diabetic rats, which normally exhibit increased AGE formation and high circulating levels of the hemoglobin Amadori product, HbA1c, and the hemoglobin AGE product, Hb-AGE. In this model study, diabetic rats fed an ethanol diet for 4 weeks showed a 52% decrease in Hb-AGE when compared with diabetic controls (P < 0.001). Circulating levels of HbA1c were unaffected by ethanol, pointing to the specificity of the acetaldehyde reaction for the post-Amadori, advanced glycation process. These data suggest a possible mechanism for the so-called "French paradox," (the cardioprotection conferred by moderate ethanol ingestion) and may offer new strategies for inhibiting advanced glycation.

  1. Second generation 2-aminoimidazole based advanced glycation end product inhibitors and breakers.

    PubMed

    Furlani, Robert E; Richardson, Mike A; Podell, Brendan K; Ackart, David F; Haugen, Jessica D; Melander, Roberta J; Basaraba, Randall J; Melander, Christian

    2015-11-01

    The formation of advanced glycation end-products (AGE) as a result of the action of reducing sugars on host macromolecules plays a role in increased morbidity of diabetic patients. There are currently no clinically available therapeutics for the prevention or eradication of AGEs. Following our previous identification of 2-aminoimidazole (2-AI) based AGE inhibitors and breakers, we now report the use of a rapid, scalable, two-step procedure to access a second generation of 2-AI based anti-AGE compounds from commercially available amino acids. Several second generation compounds exhibit increased AGE inhibition and breaking activty compared to the first generation compounds and to the known AGE inhibitor aminoguanidine.

  2. The clinical relevance of assessing advanced glycation endproducts accumulation in diabetes.

    PubMed

    Meerwaldt, Robbert; Links, Thera; Zeebregts, Clark; Tio, Rene; Hillebrands, Jan-Luuk; Smit, Andries

    2008-10-07

    Cardiovascular disease is the major cause of morbidity and mortality associated with diabetes. There is increasing evidence that advanced glycation endproducts (AGEs) play a pivotal role in atherosclerosis, in particular in diabetes. AGE accumulation is a measure of cumulative metabolic and oxidative stress, and may so represent the "metabolic memory". Furthermore, increased AGE accumulation is closely related to the development of cardiovascular complications in diabetes. This review article will focus on the clinical relevance of measuring AGE accumulation in diabetic patients by focusing on AGE formation, AGEs as predictors of long-term complications, and interventions against AGEs.

  3. The clinical relevance of assessing advanced glycation endproducts accumulation in diabetes

    PubMed Central

    Meerwaldt, Robbert; Links, Thera; Zeebregts, Clark; Tio, Rene; Hillebrands, Jan-Luuk; Smit, Andries

    2008-01-01

    Cardiovascular disease is the major cause of morbidity and mortality associated with diabetes. There is increasing evidence that advanced glycation endproducts (AGEs) play a pivotal role in atherosclerosis, in particular in diabetes. AGE accumulation is a measure of cumulative metabolic and oxidative stress, and may so represent the "metabolic memory". Furthermore, increased AGE accumulation is closely related to the development of cardiovascular complications in diabetes. This review article will focus on the clinical relevance of measuring AGE accumulation in diabetic patients by focusing on AGE formation, AGEs as predictors of long-term complications, and interventions against AGEs. PMID:18840258

  4. Receptor for Advanced Glycation End Products Regulates Leukotriene B4 Receptor 1 Signaling.

    PubMed

    Ichiki, Takako; Koga, Tomoaki; Yokomizo, Takehiko

    2016-12-01

    Leukotriene B4 receptor 1 (BLT1), a high-affinity G protein-coupled receptor (GPCR) for leukotriene B4 (LTB4), plays important roles in inflammatory and immune reactions. Although the LTB4-BLT1 axis is known to promote inflammation, the binding proteins that modulate LTB4-BLT1 signaling have not been identified. Recently, we discovered that receptor for advanced glycation end products (RAGE) interacts with BLT1 and modulates LTB4-BLT1 signaling. We propose RAGE as a new class of GPCR modulator and a new target of future GPCR studies.

  5. Vascular effects of advanced glycation endproducts: Clinical effects and molecular mechanisms☆

    PubMed Central

    Stirban, Alin; Gawlowski, Thomas; Roden, Michael

    2013-01-01

    The enhanced generation and accumulation of advanced glycation endproducts (AGEs) have been linked to increased risk for macrovascular and microvascular complications associated with diabetes mellitus. AGEs result from the nonenzymatic reaction of reducing sugars with proteins, lipids, and nucleic acids, potentially altering their function by disrupting molecular conformation, promoting cross-linking, altering enzyme activity, reducing their clearance, and impairing receptor recognition. AGEs may also activate specific receptors, like the receptor for AGEs (RAGE), which is present on the surface of all cells relevant to atherosclerotic processes, triggering oxidative stress, inflammation and apoptosis. Understanding the pathogenic mechanisms of AGEs is paramount to develop strategies against diabetic and cardiovascular complications. PMID:24634815

  6. Dietary advanced glycation end products and their role in health and disease.

    PubMed

    Uribarri, Jaime; del Castillo, María Dolores; de la Maza, María Pía; Filip, Rosana; Gugliucci, Alejandro; Luevano-Contreras, Claudia; Macías-Cervantes, Maciste H; Markowicz Bastos, Deborah H; Medrano, Alejandra; Menini, Teresita; Portero-Otin, Manuel; Rojas, Armando; Sampaio, Geni Rodrigues; Wrobel, Kazimierz; Wrobel, Katarzyna; Garay-Sevilla, Ma Eugenia

    2015-07-01

    Over the past 2 decades there has been increasing evidence supporting an important contribution from food-derived advanced glycation end products (AGEs) to the body pool of AGEs and therefore increased oxidative stress and inflammation, processes that play a major role in the causation of chronic diseases. A 3-d symposium (1st Latin American Symposium of AGEs) to discuss this subject took place in Guanajuato, Mexico, on 1-3 October 2014 with the participation of researchers from several countries. This review is a summary of the different presentations and subjects discussed, and it is divided into 4 sections. The first section deals with current general knowledge about AGEs. The second section dwells on mechanisms of action of AGEs, with special emphasis on the receptor for advanced glycation end products and the potential role of AGEs in neurodegenerative diseases. The third section discusses different approaches to decrease the AGE burden. The last section discusses current methodologic problems with measurement of AGEs in different samples. The subject under discussion is complex and extensive and cannot be completely covered in a short review. Therefore, some areas of interest have been left out because of space. However, we hope this review illustrates currently known facts about dietary AGEs as well as pointing out areas that require further research.

  7. Advanced glycation end products (AGEs) are cross-sectionally associated with insulin secretion in healthy subjects.

    PubMed

    Forbes, Josephine M; Sourris, Karly C; de Courten, Maximilian P J; Dougherty, Sonia L; Chand, Vibhasha; Lyons, Jasmine G; Bertovic, David; Coughlan, Melinda T; Schlaich, Markus P; Soldatos, Georgia; Cooper, Mark E; Straznicky, Nora E; Kingwell, Bronwyn A; de Courten, Barbora

    2014-02-01

    It has been postulated that chronic exposure to high levels of advanced glycation end products (AGEs), in particular from dietary sources, can impair insulin secretion. In the present study, we investigated the cross-sectional relationship between AGEs and acute insulin secretion during an intravenous glucose tolerance test (IVGTT) and following a 75 g oral glucose tolerance test (OGTT) in healthy humans. We report the cross-sectional association between circulating AGE concentrations and insulin secretory function in healthy humans (17 F: 27 M, aged 30 ± 10 years) with a wide range of BMI (24.6-31.0 kg/m(2)). Higher circulating concentrations of AGEs were related to increased first phase insulin secretion during IVGTT (r = 0.43; p < 0.05) and lower 2-h glucose concentrations during OGTT (r = -0.31; p < 0.05). In addition, fasting (r = -0.36; p < 0.05) and 2-h glucose concentrations were negatively related to circulating levels of soluble receptor for AGE (RAGE) isoforms (r = -0.39; p < 0.01). In conclusion, in healthy humans, we show a cross-sectional association between advanced glycation end products and acute insulin secretion during glucose tolerance testing.

  8. Relationship of Advanced Glycation End Products With Cardiovascular Disease in Menopausal Women.

    PubMed

    Pertynska-Marczewska, Magdalena; Merhi, Zaher

    2015-07-01

    Cardiovascular disease (CVD) represents the most significant cause of death in postmenopausal women. Advanced glycation end products (AGEs) are formed by nonenzymatic modification of proteins, lipids, and nucleic acids by glucose. This review focuses on the contribution of AGEs and their receptors to the development of CVD in menopause. Advanced glycation end products circulate and activate the proinflammatory endothelial cell surface receptor called RAGE, bind to the extracellular matrix of the cardiovascular system, or bind to the circulating anti-inflammatory soluble form of RAGE (sRAGE). Data emerging from human and animal studies suggest that AGEs and both receptors (RAGE and sRAGE) are implicated in the pathophysiology of CVD. Particular emphasis has been given to the role of AGE-RAGE axis in oxidative stress, inflammation, endothelial cell toxicity, and progression of atherosclerosis in menopause. Data accruing from human and animal studies suggest that RAGE expression level and circulating sRAGE level are associated with estradiol and are correlated with CVD risk factors, such as adiposity, dyslipidemia, insulin resistance, diabetes, and metabolic syndrome. By recognizing the impact of AGEs on atherosclerosis, pharmacological strategies targeting the AGE-RAGE pathway hold therapeutic potential for CVD in menopausal women.

  9. Internalization of the receptor for advanced glycation end products (RAGE) is required to mediate intracellular responses.

    PubMed

    Sevillano, Natalia; Girón, María D; Salido, Mercedes; Vargas, Alberto M; Vilches, José; Salto, Rafael

    2009-01-01

    To dissect the rat receptor for advanced glycation end products (RAGE) subcellular distribution and trafficking in eukaryotic cells, an expression system coding for a fusion protein between the RAGE and an enhanced green fluorescent protein (EGFP) has been used. The RAGE-EGFP protein is expressed at the plasma membrane of CHO-k1 and Neuro-2a (N2a) cells and retains the capacity to bind Texas Red-labelled advanced glycation end products (AGEs). AGEs addition to the cell cultures induced a change in the subcellular distribution of the fluorescent RAGE-EGFP protein compatible with an internalization of the AGEs-RAGE complex. Furthermore, while N2a cells expressing the RAGE-EGFP showed an increase in ERK1/2 phosphorylation and NF-kappaB DNA binding in response to AGEs, pre-incubation with dansyl-cadaverine or phenylarsine oxide, inhibitors of receptors internalization, blocked the activation of ERKs and other intracellular responses mediated by AGEs. These results suggest that internalization plays a key role in the signal transduction mediated by RAGE.

  10. Screening system of blocking agents of the receptor for advanced glycation endproducts in cells using fluorescence.

    PubMed

    Jung, Dong Ho; Kim, Young Sook; Kim, Jin Sook

    2012-01-01

    Activation of the receptor for advanced glycation endproducts (RAGE) triggers cellular responses implicated in the pathogenesis of diabetic complications; blockade of RAGE has been shown to inhibit the development of diabetic complications. To develop a screening system to identify novel disruptors of advanced glycation endproducts (AGE)-RAGE binding, we used an AGE-RAGE binding system in RAGE-overexpressing cells; test compounds were screened using this system. To construct human RAGE-overexpressing cells, mouse mesangial cells (MMCs) were stably transfected with the pcDNA-human RAGE (hRAGE) vector and selected under 1 mg/mL gentamicin (G418). RAGE expression in hRAGE-overexpressing MMCs was analyzed by Western blotting with specific RAGE antibody. To identify novel disruptors of AGE-RAGE binding, 50 single compounds and AGE-bovine serum albumin (BSA)-Alexa 488 (AGE-BSA labeled with Alexa 488) were treated to the hRAGE-overexpressing MMCs. Nonbinding AGE-BSA-Alexa 488 was washed and fluorescence measured by microtiter plate reader (excitation wavelength, 485 nm; emission wavelength, 528 nm). In hRAGE-overexpressing cells, only treatment with AGE-BSA-Alexa 488 significantly increased fluorescence intensity in a dose-dependent manner. Of 50 compounds tested, genistein disrupted AGE-RAGE binding in a dose-dependent manner. This AGE-RAGE binding system using AGE-BSA-Alexa 488 in hRAGE-overexpressing cells was suitable for screening of agents that disrupt AGE-hRAGE binding.

  11. [Role of the receptor for advanced glycation end products (RAGE) in inflammation].

    PubMed

    Mosquera, Jesús A

    2010-06-01

    The receptor for advanced glycation end products (RAGE) is a transmembrane protein on the cellular surface that recognizes tridimensional molecules, instead of aminoacid sequences, making this molecule capable of interacting with diverse ligands. RAGE represents an important factor in innate immunity against pathogens, but it also interacts with endogenous ligands, resulting in chronic inflammation. RAGE signaling has been implicated in multiple human illnesses, including diabetes, atherosclerosis, arthritis, Alzheimer's disease, atherosclerosis and aging associated diseases. In addition to advanced glycation end products (AGE), RAGE has other important ligands such as: high mobility group box 1 protein (HMGB1, also termed amphoterin), the group of calcium binding cellular factors S100 (also termed calgranulin), amiloid beta peptides and Mac-1, a beta-2 integrin (CD1lb/CD18). Ligation of RAGE on the cellular surface triggers a series of cellular signaling events, including the activation and translocation to the nucleus of transcription factor NF-kappaB, leading to the production of pro-inflammatory cytokines, chemokines, adhesion molecules and oxidative stress and causing inflammation. More recent work has revealed the role of RAGE in inflammatory cell recruitment and extravasation of leukocytes across the endothelial barrier with further inflammatory events. Recent therapeutic strategies show that RAGE is an important target to treat RAGE activation-associated diseases.

  12. Dietary Advanced Glycation End Products and Their Role in Health and Disease12

    PubMed Central

    Uribarri, Jaime; del Castillo, María Dolores; de la Maza, María Pía; Filip, Rosana; Gugliucci, Alejandro; Luevano-Contreras, Claudia; Macías-Cervantes, Maciste H; Markowicz Bastos, Deborah H; Medrano, Alejandra; Menini, Teresita; Portero-Otin, Manuel; Rojas, Armando; Sampaio, Geni Rodrigues; Wrobel, Kazimierz; Wrobel, Katarzyna; Garay-Sevilla, Ma Eugenia

    2015-01-01

    Over the past 2 decades there has been increasing evidence supporting an important contribution from food-derived advanced glycation end products (AGEs) to the body pool of AGEs and therefore increased oxidative stress and inflammation, processes that play a major role in the causation of chronic diseases. A 3-d symposium (1st Latin American Symposium of AGEs) to discuss this subject took place in Guanajuato, Mexico, on 1–3 October 2014 with the participation of researchers from several countries. This review is a summary of the different presentations and subjects discussed, and it is divided into 4 sections. The first section deals with current general knowledge about AGEs. The second section dwells on mechanisms of action of AGEs, with special emphasis on the receptor for advanced glycation end products and the potential role of AGEs in neurodegenerative diseases. The third section discusses different approaches to decrease the AGE burden. The last section discusses current methodologic problems with measurement of AGEs in different samples. The subject under discussion is complex and extensive and cannot be completely covered in a short review. Therefore, some areas of interest have been left out because of space. However, we hope this review illustrates currently known facts about dietary AGEs as well as pointing out areas that require further research. PMID:26178030

  13. Advanced Glycation End Products in Foods and a Practical Guide to Their Reduction in the Diet

    PubMed Central

    URIBARRI, JAIME; WOODRUFF, SANDRA; GOODMAN, SUSAN; CAI, WEIJING; CHEN, XUE; PYZIK, RENATA; YONG, ANGIE; STRIKER, GARY E.; VLASSARA, HELEN

    2013-01-01

    Modern diets are largely heat-processed and as a result contain high levels of advanced glycation end products (AGEs). Dietary advanced glycation end products (dAGEs) are known to contribute to increased oxidant stress and inflammation, which are linked to the recent epidemics of diabetes and cardiovascular disease. This report significantly expands the available dAGE database, validates the dAGE testing methodology, compares cooking procedures and inhibitory agents on new dAGE formation, and introduces practical approaches for reducing dAGE consumption in daily life. Based on the findings, dry heat promotes new dAGE formation by >10- to 100-fold above the uncooked state across food categories. Animal-derived foods that are high in fat and protein are generally AGE-rich and prone to new AGE formation during cooking. In contrast, carbohydrate-rich foods such as vegetables, fruits, whole grains, and milk contain relatively few AGEs, even after cooking. The formation of new dAGEs during cooking was prevented by the AGE inhibitory compound aminoguanidine and significantly reduced by cooking with moist heat, using shorter cooking times, cooking at lower temperatures, and by use of acidic ingredients such as lemon juice or vinegar. The new dAGE database provides a valuable instrument for estimating dAGE intake and for guiding food choices to reduce dAGE intake. PMID:20497781

  14. Consequences of Advanced Glycation End Products Accumulation in Chronic Kidney Disease and Clinical Usefulness of Their Assessment Using a Non-invasive Technique - Skin Autofluorescence.

    PubMed

    Oleniuc, Mihaela; Secara, Irina; Onofriescu, Mihai; Hogas, Simona; Voroneanu, Luminita; Siriopol, Dimitrie; Covic, Adrian

    2011-10-01

    Accelerated formation and accumulation of advanced glycation end-products occur under circumstances of increased supply of substrates such as hyperglycaemic or oxidative stress and in age-related and chronic diseases like diabetes mellitus, chronic renal failure, neurodegenerative diseases, osteoarthritis and also non-diabetic atherosclerosis and chronic heart failure. Advanced glycation end-products accumulation occurs especially on long-lived proteins such as collagen in the skin and in vascular basement membranes leading to vascular damage. Adequate renal clearance capacity is an important factor in the effective removal of advanced glycation end-products. The Autofluorescence Reader was developed as a marker, representative for tissue advanced glycation end-products accumulation, easily applicable in a clinical setting, initially for predicting diabetes related complications. Studies have already shown a relationship between skin autofluorescence and diabetes complications, as well as its predictive value for total and cardiovascular mortality in type 2 diabetes. Moreover skin autofluorescence was demonstrated to be superior to Haemoglobin A1c and other conventional risk factors. Advanced glycation end-products have been proposed as a novel factor involved in the development and progression of chronic heart failure. Assessment of advanced glycation end-products accumulation in end-stage renal disease and undergoing renal replacement therapies patients has become of great importance. Cardiovascular and connective tissue disorders are very common in patients with end-stage renal disease, and the accumulation of advanced glycation end-products is significantly increased in these patients. Mortality is markedly increased in patients with decreased kidney function, particularly in patients with end-stage renal disease. Skin advanced glycation end-products levels are strong predictors of survival in haemodialysis patients independent of other established risk factors

  15. Pathophysiology of diabetic erectile dysfunction: potential contribution of vasa nervorum and advanced glycation endproducts.

    PubMed

    Cellek, S; Cameron, N E; Cotter, M A; Muneer, A

    2013-01-01

    Erectile dysfunction (ED) due to diabetes mellitus remains difficult to treat medically despite advances in pharmacotherapeutic approaches in the field. This unmet need has resulted in a recent re-focus on the pathophysiology, in order to understand the cellular and molecular mechanisms leading to ED in diabetes. Diabetes-induced ED is often resistant to PDE5 inhibitor treatment, thus there is a need to discover targets that may lead to novel approaches for a successful treatment. The aim of this brief review is to update the reader in some of the latest development on that front, with a particular focus on the role of impaired neuronal blood flow and the formation of advanced glycation endproducts.

  16. Inhibitory effects of hydroxysafflor yellow A on the formation of advanced glycation end products in vitro.

    PubMed

    Ni, Zhenzhen; Zhuge, Zhengbing; Li, Wenlu; Xu, Huimin; Zhang, Zhongmiao; Dai, Haibin

    2012-01-01

    To investigate the inhibitory effects of hydroxysafflor yellow A (HSYA) on the protein glycation in vitro. Using bovine serum albumin (BSA)-glucose assay, BSA-methylglyoxal (MGO) assay, and N-acetylglycyl-lysine methyl ester (G.K.) peptide-ribose assay, inhibitory effects of HSYA were investigated. Advanced glycation end products (AGEs) production was assessed by AGEs-specific fluorescence and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In BSA-glucose assay, HSYA concentration dependently decreased AGEs formation, with maximum inhibitory effects at 1 mM by 95%. Further more, HSYA also showed significant inhibitory effects on MGO-medicated protein modification and subsequent cross-linking of proteins. Finally, when co-incubated with G.K. peptide and ribose, HSYA exhibited its antiglycation effects, and the maximum inhibitory effects of HSYA at 1 mM were 84%. Overall, our present study provides the first evidence of the antiglycation effects of HSYA on AGEs formation in vitro.

  17. Olive Leaf Extracts Are a Natural Source of Advanced Glycation End Product Inhibitors

    PubMed Central

    Charisiadis, Pantelis; Margianni, Evangelia; Lamari, Fotini N.; Gerothanassis, Ioannis P.

    2013-01-01

    Abstract Advanced glycation end products (AGEs), which are readily formed and accumulated with sustained hyperglycemia, contribute to the development of diabetic complications. As a consequence, inhibition of AGE formation constitutes an attractive therapeutic/preventive target. In the current study, we explored the phytochemical composition and the in vitro effect of two different olive leaf extracts (an aqueous and a methanolic) on AGE formation. The methanolic olive leaf extract inhibited fluorescent AGE formation in a bovine serum albumin (BSA)-ribose system, whereas the aqueous extract had no effect in both BSA-fructose and BSA-ribose systems. The phytochemical profile was investigated with liquid chromatography-ultraviolet-visible (UV-Vis) diode array coupled to electrospray ionization multistage mass spectrometry (LC/DAD/ESI-MSn). Quantification of the major phenolic compounds was performed with high performance liquid chromatography with UV-Vis diode array detection and nuclear magnetic resonance spectroscopy. Among the major phenolic components (luteolin, hydroxytyrosol, luteolin-4′-O-β-D-glucopyranoside, luteolin-7-O-β-D-glucopyranoside, and oleuropein), luteolin and luteolin-4′-O-β-D-glucopyranoside were assigned as potent inhibitors of AGE formation. The extraction procedure greatly affects the composition and therefore the anti-glycation potential of olive leaves. PMID:24044491

  18. Advanced Glycation End Products: A Molecular Target for Vascular Complications in Diabetes.

    PubMed

    Yamagishi, Sho-Ichi; Nakamura, Nobutaka; Suematsu, Mika; Kaseda, Kuniyoshi; Matsui, Takanori

    2015-10-27

    A nonenzymatic reaction between reducing sugars and amino groups of proteins, lipids and nucleic acids contributes to the aging of macromolecules and subsequently alters their structural integrity and function. This process has been known to progress at an accelerated rate under hyperglycemic and/or oxidative stress conditions. Over a course of days to weeks, early glycation products undergo further reactions such as rearrangements and dehydration to become irreversibly cross-linked, fluorescent and senescent macroprotein derivatives termed advanced glycation end products (AGEs). There is a growing body of evidence indicating that interaction of AGEs with their receptor (RAGE) elicits oxidative stress generation and as a result evokes proliferative, inflammatory, thrombotic and fibrotic reactions in a variety of cells. This evidence supports AGEs' involvement in diabetes- and aging-associated disorders such as diabetic vascular complications, cancer, Alzheimer's disease and osteoporosis. Therefore, inhibition of AGE formation could be a novel molecular target for organ protection in diabetes. This report summarizes the pathophysiological role of AGEs in vascular complications in diabetes and discusses the potential clinical utility of measurement of serum levels of AGEs for evaluating organ damage in diabetes.

  19. Accumulation of advanced glycation end products and chronic complications in ESRD treated by dialysis.

    PubMed

    Meerwaldt, Robbert; Zeebregts, Clark J; Navis, Gerjan; Hillebrands, Jan-Luuk; Lefrandt, Joop D; Smit, Andries J

    2009-01-01

    Cardiovascular and connective tissue disorders are very common in patients with end-stage renal disease (ESRD), and the accumulation of advanced glycation end products (AGEs) is significantly increased in these patients. Accumulation of AGEs is believed to have a role in tissue protein aging and the pathogenesis of such age-related diseases as diabetes and ESRD. AGEs accumulate in patients with ESRD as a result of nonenzymatic glycation, oxidative stress, and diminished clearance of AGE precursors. Some AGEs show characteristic brown pigmentation and fluorescence, form protein-protein cross-links, and may ligate with AGE-specific receptors, inducing oxidative stress and cytokine production. This review focuses on the clinical relevance of AGE accumulation in patients with ESRD treated by dialysis for the development of long-term complications. The formation and accumulation of AGEs in patients with ESRD are discussed, as well as the relationship between AGE accumulation and such major complications of ESRD as cardiovascular and connective tissue disorders.

  20. Ameliorating Effect of Akebia quinata Fruit Extracts on Skin Aging Induced by Advanced Glycation End Products.

    PubMed

    Shin, Seoungwoo; Son, Dahee; Kim, Minkyung; Lee, Seungjun; Roh, Kyung-Baeg; Ryu, Dehun; Lee, Jongsung; Jung, Eunsun; Park, Deokhoon

    2015-11-12

    The accumulation of free radicals and advanced glycation end products (AGEs) in the skin plays a very important role in skin aging. Both are known to interact with each other. Therefore, natural compounds or extracts that possess both antioxidant and antiglycation activities might have great antiageing potential. Akebia quinata fruit extract (AQFE) has been used to treat urinary tract inflammatory disease in traditional Korean and Chinese medicines. In the present study, AQFE was demonstrated to possess antioxidant and antiglycation activity. AQFE protects human dermal fibroblasts (HDFs) from oxidative stress and inhibits cellular senescence induced by oxidative stress. We also found that AQFE inhibits glycation reaction between BSA and glucose. The antiglycation activity of AQFE was dose-dependent. In addition, the antiglycation activity of AQFE was confirmed in a human skin explant model. AQFE reduced CML expression and stimulated fibrillin-1 expression in comparison to the methyglyoxal treatment. In addition, the possibility of the extract as an anti-skin aging agent has also been clinically validated. Our analysis of the crow's feet wrinkle showed that there was a decrease in the depth of deep furrows in RI treated with AQFE cream over an eight-week period. The overall results suggest that AQFE may work as an anti-skin aging agent by preventing oxidative stress and other complications associated with AGEs formation.

  1. Detection of Free Advanced Glycation End Products in Vivo during Hemodialysis.

    PubMed

    Hohmann, Christoph; Liehr, Kristin; Henning, Christian; Fiedler, Roman; Girndt, Matthias; Gebert, Michael; Hulko, Michael; Storr, Markus; Glomb, Marcus A

    2017-02-01

    Advanced glycation end products (AGEs) are often regarded as glycotoxins, which are normally removed by the kidney. Patients with end-stage renal failure rely on hemodialysis (HD) treatment to eliminate these compounds. In the present work, a highly selective LC-MS/MS method was used for quantitation of AGE levels in plasma and in dialysis fluids of HD patients, with a focus on AGE-free adducts. A broad range of 19 amino acid modifications was identified and quantitated. It was expected that the AGE-free adducts are successfully eliminated by dialysis treatment. Indeed, with a mean elimination rate of 71%, this assumption proved to be valid for all target analytes with the exception of pyrraline, which showed an opposite behavior. Here, plasma and dialysate levels increased during the treatment by about 59%. The notions that pyrraline was formed in high amounts in the patient's bloodstream (I) after intake of the corresponding precursor compound 3-deoxyglucosone with the dialysis fluid or (II) by catalytic effects on the formation by the dialysis membrane were ruled out. In contrast, in a dietary study, the comparison of pyrraline concentrations in plasma before and after food consumption confirmed that the increase in pyrraline originates solely from digestion of glycated food proteins. Additionally, by detailed analyses of the food consumed during dialysis sessions, bread rolls with a pyrraline content of about 21.7 μmol per serving were identified as the main source.

  2. Mangostanaxanthones III and IV: advanced glycation end-product inhibitors from the pericarp of Garcinia mangostana.

    PubMed

    Abdallah, Hossam M; El-Bassossy, Hany M; Mohamed, Gamal A; El-Halawany, Ali M; Alshali, Khalid Z; Banjar, Zainy M

    2017-01-01

    Advanced glycation end-products (AGEs) are associated with a non-enzymatic reaction between the amino group of a protein and the carbonyl group of a sugar during hyperglycemia. The precipitation of AGEs in different tissues leads to many complications, such as endothelial dysfunction, cardiovascular complications, atherosclerosis, retinopathy, neuropathy, and Alzheimer's disease. Garcinia mangostana L. (Clusiaceae) (GM) was selected owing to the ability of its polar and non-polar fractions to inhibit AGE formation. For the first time, the bioguided fractionation of its pericarp MeOH extract (GMT) gave rise to two new xanthones, namely, mangostanaxanthones III (1) and IV (3), in addition to six known compounds, β-mangostin (2), garcinone E (4), rubraxanthone (5), α-mangostin (6), garcinone C (7), and 9-hydroxycalabaxanthone (8), from the non-polar faction. Their structures were verified by various spectroscopic methods, including 1D and 2D NMR studies and high-resolution MS data. All of the isolated xanthones significantly inhibited both sugar (ribose) and dicarbonyl compound (methylglyoxal)-induced protein glycation in a dose-dependent manner. This is explained by the ability of the isolated xanthones to inhibit protein oxidation, as indicated by the decreases in dityrosine and N'-formylkynurenine formation.

  3. Singlet oxygen induced advanced glycation end-product photobleaching of in vivo human fingertip autofluorescence

    NASA Astrophysics Data System (ADS)

    Deng, Bin; Simental, Anabel; Lutz, Patrick; Shaheen, George; Chaiken, Joseph

    2012-01-01

    Nonenzymatic glycation and oxidation of ubiquitous proteins in vivo leads to irreversible formation of advanced glycation end products (AGEs). Due to their relatively long half life and low clearance rate AGEs tend to accumulate within static tissues and the circulatory system. Spectra obtained using 830 nm near-infrared (NIR) excitation suggest that the so-called "autofluorescence" from all tissues has a finite number of sources but the fact that senior and diabetic subjects produce more than other members of the general population suggests that a significant portion of the total autofluorescence from all sources originates from AGEs. Using pentosidine generated in a reaction mixture as described by Monnier as representative, an in vitro study unveiled very similar fluorescence and photobleaching pattern as observed for autofluorescence in vivo. A series of oxygen, air and argon purging experiments on the pentosidine-generating reaction mixture suggests that pentosidine is a singlet oxygen sensitizer and secondary reactions between the pentosidine itself and/or other fluorophores and the photosensitized singlet oxygen explain the observed photobleaching. Ab initio Gaussian calculations on pentosidine reveal the existence of low-lying triplet excited states required for the sensitization of ground state oxygen. A commercially available product known as singlet oxygen sensor green (SOSG) that specifically serves as a singlet oxygen detection reagent confirms the generation of singlet oxygen from NIR irradiated pentosidine trimixture. This study provides one definite chemical mechanism for understanding in vivo human skin autofluorescence and photobleaching.

  4. Olive leaf extracts are a natural source of advanced glycation end product inhibitors.

    PubMed

    Kontogianni, Vassiliki G; Charisiadis, Pantelis; Margianni, Evangelia; Lamari, Fotini N; Gerothanassis, Ioannis P; Tzakos, Andreas G

    2013-09-01

    Advanced glycation end products (AGEs), which are readily formed and accumulated with sustained hyperglycemia, contribute to the development of diabetic complications. As a consequence, inhibition of AGE formation constitutes an attractive therapeutic/preventive target. In the current study, we explored the phytochemical composition and the in vitro effect of two different olive leaf extracts (an aqueous and a methanolic) on AGE formation. The methanolic olive leaf extract inhibited fluorescent AGE formation in a bovine serum albumin (BSA)-ribose system, whereas the aqueous extract had no effect in both BSA-fructose and BSA-ribose systems. The phytochemical profile was investigated with liquid chromatography-ultraviolet-visible (UV-Vis) diode array coupled to electrospray ionization multistage mass spectrometry (LC/DAD/ESI-MS(n)). Quantification of the major phenolic compounds was performed with high performance liquid chromatography with UV-Vis diode array detection and nuclear magnetic resonance spectroscopy. Among the major phenolic components (luteolin, hydroxytyrosol, luteolin-4'-O-β-D-glucopyranoside, luteolin-7-O-β-D-glucopyranoside, and oleuropein), luteolin and luteolin-4'-O-β-D-glucopyranoside were assigned as potent inhibitors of AGE formation. The extraction procedure greatly affects the composition and therefore the anti-glycation potential of olive leaves.

  5. Effect of taurine on advanced glycation end products-induced hypertrophy in renal tubular epithelial cells

    SciTech Connect

    Huang, J.-S. Chuang, L.-Y.; Guh, J.-Y.; Yang, Y.-L.; Hsu, M.-S.

    2008-12-01

    Mounting evidence indicates that advanced glycation end products (AGE) play a major role in the development of diabetic nephropathy (DN). Taurine is a well documented antioxidant agent. To explore whether taurine was linked to altered AGE-mediated renal tubulointerstitial fibrosis in DN, we examined the molecular mechanisms of taurine responsible for inhibition of AGE-induced hypertrophy in renal tubular epithelial cells. We found that AGE (but not non-glycated BSA) caused inhibition of cellular mitogenesis rather than cell death by either necrosis or apoptosis. There were no changes in caspase 3 activity, bcl-2 protein expression, and mitochondrial cytochrome c release in BSA, AGE, or the antioxidant taurine treatments in these cells. AGE-induced the Raf-1/extracellular signal-regulated kinase (ERK) activation was markedly blocked by taurine. Furthermore, taurine, the Raf-1 kinase inhibitor GW5074, and the ERK kinase inhibitor PD98059 may have the ability to induce cellular proliferation and cell cycle progression from AGE-treated cells. The ability of taurine, GW5074, or PD98059 to inhibit AGE-induced hypertrophy was verified by the observation that it significantly decreased cell size, cellular hypertrophy index, and protein levels of RAGE, p27{sup Kip1}, collagen IV, and fibronectin. The results obtained in this study suggest that taurine may serve as the potential anti-fibrotic activity in DN through mechanism dependent of its Raf-1/ERK inactivation in AGE-induced hypertrophy in renal tubular epithelial cells.

  6. Collagen advanced glycation inhibits its Discoidin Domain Receptor 2 (DDR2)-mediated induction of lysyl oxidase in osteoblasts.

    PubMed

    Khosravi, Roozbeh; Sodek, Katharine L; Faibish, Michael; Trackman, Philip C

    2014-01-01

    Diabetes increases the risk of bone fracture. Organic and inorganic bone extracellular matrix components determine bone strength. Previous studies indicate that in diabetes, glycation of collagen causes abnormal arrangements of collagen molecules and fragile bones. Diabetic bone fragility is additionally attributed to reduced levels of lysyl oxidase enzyme-dependent collagen cross-links. The mechanism underlying the presence of lower enzymatic collagen cross-links in diabetic bone has not been directly investigated. Here we determine in primary osteoblast cultures the regulation of lysyl oxidase protein by type I collagen and collagen modified by carboxymethylation (CML-collagen), a form of advanced glycation endproducts. Data indicate that non-glycated collagen up-regulates lysyl oxidase levels both in primary non-differentiated and in differentiating mouse and rat osteoblast cultures, while CML-collagen fails to regulate lysyl oxidase in these cells. Collagen binding to Discoidin Domain Receptor-2 (DDR2) mediates lysyl oxidase increases, determined in DDR2 shRNA knockdown studies. DDR2 binding and activation were disrupted by collagen glycation, pointing to a mechanism for the diminished levels of lysyl oxidase and consequently low lysyl oxidase-derived cross-links in diabetic bone. Our studies indicate that collagen-integrin interactions may not play a major role in up-regulating lysyl oxidase. Furthermore, non-collagenous ligands for the receptor for advanced glycation end products (RAGE) failed to alter lysyl oxidase levels. Taken together with published studies a new understanding emerges in which diabetes- and age-dependent inhibition of normal collagen-stimulated DDR2- and integrin-signaling, and independent advanced glycation-stimulated RAGE-signaling, each contributes to different aspects of diabetic osteopenia.

  7. Collagen Advanced Glycation Inhibits Its Discoidin Domain Receptor 2 (DDR2)-Mediated Induction of Lysyl Oxidase in Osteoblasts

    PubMed Central

    Khosravi, Roozbeh; Sodek, Katharine L.; Faibish, Michael; Trackman, Philip C.

    2013-01-01

    Diabetes increases the risk of bone fracture. Organic and inorganic bone extracellular matrix components determine bone strength. Previous studies indicate that in diabetes, glycation of collagen causes abnormal arrangements of collagen molecules and fragile bones. Diabetic bone fragility is additionally attributed to reduced levels of lysyl oxidase enzyme-dependent collagen cross-links. The mechanism underlying the presence of lower enzymatic collagen cross-links in diabetic bone has not been directly investigated. Here we determine in primary osteoblast cultures the regulation of lysyl oxidase protein by type I collagen and collagen modified by carboxymethylation (CML-collagen), a form of advanced glycation endproducts. Data indicate that non-glycated collagen up-regulates lysyl oxidase levels both in primary non-differentiated and in differentiating mouse and rat osteoblast cultures, while CML-collagen fails to regulate lysyl oxidase in these cells. Collagen binding to Discoidin Domain Receptor-2 (DDR2) mediates lysyl oxidase increases, determined in DDR2 shRNA knockdown studies. DDR2 binding and activation were disrupted by collagen glycation, pointing to a mechanism for the diminished levels of lysyl oxidase and consequent low lysyl oxidase-derived cross-links in diabetic bone. Our studies indicate that collagen-integrin interactions may not play a major role in up-regulating lysyl oxidase. Furthermore, non-collagenous ligands for the receptor for advanced glycation end products (RAGE) failed to alter lysyl oxidase levels. Taken together with published studies a new understanding emerges in which diabetes- and age-dependent inhibition of normal collagen-stimulated DDR2- and integrin-signaling, and independent advanced glycation-stimulated RAGE-signaling, each contributes to different aspects of diabetic osteopenia. PMID:24120383

  8. Characterizing harmful advanced glycation end-products (AGEs) and ribosylated aggregates of yellow mustard seed phytocystatin: Effects of different monosaccharides

    NASA Astrophysics Data System (ADS)

    Ahmed, Azaj; Shamsi, Anas; Bano, Bilqees

    2017-01-01

    Advanced glycation end products (AGEs) are at the core of variety of diseases ranging from diabetes to renal failure and hence gaining wide consideration. This study was aimed at characterizing the AGEs of phytocystatin isolated from mustard seeds (YMP) when incubated with different monosaccharides (glucose, ribose and mannose) using fluorescence, ultraviolet, circular dichroism (CD) spectroscopy and microscopy. Ribose was found to be the most potent glycating agent as evident by AGEs specific fluorescence and absorbance. YMP exists as a molten globule like structure on day 24 as depicted by high ANS fluorescence and altered intrinsic fluorescence. Glycated YMP as AGEs and ribose induced aggregates were observed at day 28 and 32 respectively. In our study we have also examined the anti-aggregative potential of polyphenol, resveratrol. Our results suggested the anti-aggregative behavior of resveratrol as it prevented the in vitro aggregation of YMP, although further studies are required to decode the mechanism by which resveratrol prevents the aggregation.

  9. Monacolin K and monascin attenuated pancreas impairment and hyperglycemia induced by advanced glycation endproducts in BALB/c mice.

    PubMed

    Hsu, Wei-Hsuan; Lu, Si-Shi; Lee, Bao-Hong; Hsu, Ya-Wen; Pan, Tzu-Ming

    2013-12-01

    Several lines of evidence have implicated high levels of advanced glycation endproducts (AGEs) in diabetes. Pancreas impairment caused by AGEs has been found in recent studies. Monascin (MS) and monacolin K (MK) are active compounds identified from Monascus-fermented products, which have been reported to inhibit inflammation and improve insulin resistance. In order to confirm the protective effects of MS and MK on pancreatic function, BALB/c mice were treated with AGEs via intraperitoneal injection for 22 weeks to induce hyperglycemia, and the pancreas-protecting mechanism of MS and MK from AGE-induced damage was investigated. We found that the expression of pancreatic and duodenal homeobox-1 (PDX-1) and glucose transporter 2 (GLUT2) was recovered by MS or MK administration to AGE-treated mice. In addition, MS strongly improved performance in the oral glucose tolerance test (OGTT) and the insulin tolerance test (ITT), suggesting that MS sensitized to insulin in AGE-treated mice. Both MS and MK elevated pancreatic insulin expression when compared to the AGE-treated group, suggesting that MS and MK attenuated AGE-induced pancreatic dysfunction. Histopathology studies showed that intraperitoneal injection of AGEs did not result in pancreas damage. These findings confirm that the potential mechanism of AGEs on pancreatic dysfunction involves the induction of inflammation and the suppression of PDX-1 and GLUT2 expression. Taken together, MS and MK may be developed as an anti-diabetic agent in the future.

  10. Litsea japonica extract inhibits neuronal apoptosis and the accumulation of advanced glycation end products in the diabetic mouse retina.

    PubMed

    Kim, Junghyun; Kim, Chan-Sik; Lee, Yun Mi; Sohn, Eunjin; Jo, Kyuhyung; Kim, Jin Sook

    2015-07-01

    The retinal accumulation of advanced glycation end products (AGEs) is a condition, which is found in diabetic retinopathy. The purpose of the present study was to investigate the protective effect of Litsea japonica extract (LJE) and to elucidate its underlying protective mechanism in model diabetic db/db mice. Male, 7 -week-old db/db mice were treated with LJE (100 or 250 mg/kg body weight) once a day orally for 12 weeks. The expression levels of AGEs and their receptor (RAGE) were subsequently assessed by immunohistochemistry. An electrophoretic mobility shift assay and southwestern histochemistry were used to detect activated nuclear factor κB (NF-κB). The immunohistochemical analysis demonstrated that LJE significantly reduced the expression levels of the AGEs and RAGE in the neural retinas of the db/db mice. LJE markedly inhibited the apoptosis of retinal ganglion cells. In addition, LJE suppressed the activation of NF-κB. These results suggested that LJE may be beneficial for the treatment of diabetes-induced retinal neurodegeneration, and the ability of LJE to attenuate retinal ganglion cell loss may be mediated by inhibition of the accumulation of AGEs.

  11. The receptor for advanced glycation end products (RAGE) specifically recognizes methylglyoxal-derived AGEs.

    PubMed

    Xue, Jing; Ray, Rashmi; Singer, David; Böhme, David; Burz, David S; Rai, Vivek; Hoffmann, Ralf; Shekhtman, Alexander

    2014-05-27

    Diabetes-induced hyperglycemia increases the extracellular concentration of methylglyoxal. Methylglyoxal-derived hydroimidazolones (MG-H) form advanced glycation end products (AGEs) that accumulate in the serum of diabetic patients. The binding of hydroimidozolones to the receptor for AGEs (RAGE) results in long-term complications of diabetes typified by vascular and neuronal injury. Here we show that binding of methylglyoxal-modified albumin to RAGE results in signal transduction. Chemically synthesized peptides containing hydroimidozolones bind specifically to the V domain of RAGE with nanomolar affinity. The solution structure of an MG-H1-V domain complex revealed that the hydroimidazolone moiety forms multiple contacts with a positively charged surface on the V domain. The high affinity and specificity of hydroimidozolones binding to the V domain of RAGE suggest that they are the primary AGE structures that give rise to AGEs-RAGE pathologies.

  12. Receptor for advanced glycation end products (RAGE) regulates sepsis but not the adaptive immune response

    PubMed Central

    Liliensiek, Birgit; Weigand, Markus A.; Bierhaus, Angelika; Nicklas, Werner; Kasper, Michael; Hofer, Stefan; Plachky, Jens; Gröne, Herman-Josef; Kurschus, Florian C.; Schmidt, Ann Marie; Yan, Shi Du; Martin, Eike; Schleicher, Erwin; Stern, David M.; Hämmerling, Günter J.; Nawroth, Peter P.; Arnold, Bernd

    2004-01-01

    While the initiation of the adaptive and innate immune response is well understood, less is known about cellular mechanisms propagating inflammation. The receptor for advanced glycation end products (RAGE), a transmembrane receptor of the immunoglobulin superfamily, leads to perpetuated cell activation. Using novel animal models with defective or tissue-specific RAGE expression, we show that in these animal models RAGE does not play a role in the adaptive immune response. However, deletion of RAGE provides protection from the lethal effects of septic shock caused by cecal ligation and puncture. Such protection is reversed by reconstitution of RAGE in endothelial and hematopoietic cells. These results indicate that the innate immune response is controlled by pattern-recognition receptors not only at the initiating steps but also at the phase of perpetuation. PMID:15173891

  13. The Receptor for Advanced Glycation End Products (RAGE) and the Lung

    PubMed Central

    Buckley, Stephen T.; Ehrhardt, Carsten

    2010-01-01

    The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin superfamily of cell surface molecules. As a pattern-recognition receptor capable of binding a diverse range of ligands, it is typically expressed at low levels under normal physiological conditions in the majority of tissues. In contrast, the lung exhibits high basal level expression of RAGE localised primarily in alveolar type I (ATI) cells, suggesting a potentially important role for the receptor in maintaining lung homeostasis. Indeed, disruption of RAGE levels has been implicated in the pathogenesis of a variety of pulmonary disorders including cancer and fibrosis. Furthermore, its soluble isoforms, sRAGE, which act as decoy receptors, have been shown to be a useful marker of ATI cell injury. Whilst RAGE undoubtedly plays an important role in the biology of the lung, it remains unclear as to the exact nature of this contribution under both physiological and pathological conditions. PMID:20145712

  14. Influence of dietary advanced glycation end products on wound healing in nondiabetic mice.

    PubMed

    Zhu, Yuanchang; Lan, Feifei; Wei, Jiange; Chong, Boonhor; Chen, Pakho; Huynh, Longquan; Wong, Nganwa; Liu, Yu

    2011-01-01

    The present study was to determine advanced glycation end products (AGEs) in foods from different processes, and the influence of dietary AGEs on wound healing in nondiabetic mice. AGEs mixtures were extracted from local fast foods and foods prepared in lab. A BSA-AGEs mixture made by incubating glucose with bovine serum albumin (BSA) was used as a positive control. Burns were made on the skin of mice. The results showed that foods processed by high temperatures generated higher dietary AGEs. Nonwounded mice showed no observable adverse response to high dietary AGEs. However, high dietary AGEs caused severe inflammatory responses in wounded mice. The plasma level of high mobility group box 1 (HMGB1) and its mRNA in white blood cells were found to be significantly higher in the wounded mice fed with high dietary AGEs than others. We conclude that dietary AGEs worsen inflammation and delay wound healing in nondiabetic burned mice, which might be mediated by HMGB1.

  15. The Receptor for Advanced Glycation End Products (RAGE) Contributes to the Progression of Emphysema in Mice

    PubMed Central

    Sambamurthy, Nisha; Leme, Adriana S.; Oury, Tim D.; Shapiro, Steven D.

    2015-01-01

    Several recent clinical studies have implied a role for the receptor for advanced glycation end products (RAGE) and its variants in chronic obstructive pulmonary disease (COPD). In this study we have defined a role for RAGE in the pathogenesis of emphysema in mice. RAGE deficient mice (RAGE-/-) exposed to chronic cigarette smoke were significantly protected from smoke induced emphysema as determined by airspace enlargement and had no significant reduction in lung tissue elastance when compared to their air exposed controls contrary to their wild type littermates. The progression of emphysema has been largely attributed to an increased inflammatory cell-mediated elastolysis. Acute cigarette smoke exposure in RAGE-/- mice revealed an impaired early recruitment of neutrophils, approximately a 6-fold decrease compared to wild type mice. Hence, impaired neutrophil recruitment with continued cigarette smoke exposure reduces elastolysis and consequent emphysema. PMID:25781626

  16. Advanced glycation end-products (AGEs) and heart failure: pathophysiology and clinical implications.

    PubMed

    Hartog, Jasper W L; Voors, Adriaan A; Bakker, Stephan J L; Smit, Andries J; van Veldhuisen, Dirk J

    2007-12-01

    Advanced glycation end-products (AGEs) are molecules formed during a non-enzymatic reaction between proteins and sugar residues, called the Maillard reaction. AGEs accumulate in the human body with age, and accumulation is accelerated in the presence of diabetes mellitus. In patients with diabetes, AGE accumulation is associated with the development of cardiac dysfunction. Enhanced AGE accumulation is not restricted to patients with diabetes, but can also occur in renal failure, enhanced states of oxidative stress, and by an increased intake of AGEs. Several lines of evidence suggest that AGEs are related to the development and progression of heart failure in non-diabetic patients as well. Preliminary small intervention studies with AGE cross-link breakers in heart failure patients have shown promising results. In this review, the role of AGEs in the development of heart failure and the role of AGE intervention as a possible treatment for heart failure are discussed.

  17. New advanced glycation end-products inhibitors from Dichrostachys cinerea Wight & Arn.

    PubMed

    Suresh, G; Tiwari, Ashok K; Radha Krishna Murthy, M; Anand Kumar, D; Rajendra Prasad, K; Ranga Rao, R; Zehra Ali, A; Suresh Babu, K

    2012-01-01

    Free radical scavenging and advanced glycation end-product (AGE) inhibitory potential were evaluated in the crude methanol extract of Dichrostachys cinerea. Bioassay-guided isolation led to the identification of four flavan-3-ols, namely (-)-mesquitol (1), oritin (2), (-)-festidinol (3) and (-)-epicatechin (4). Analysis of structure-activity relationships revealed that the presence of 7,8-dihydroxyl groups in the A-ring of flavan-3-ols in conjunction with 3',4'-dihydroxyls in the B-ring (1) is an important criterion for displaying potent AGE inhibitory activity along with free radical scavenging properties. (-)-Mesquitol (1), oritin (2), and (-)-festidinol (3) were found to be new natural AGE inhibitors. (-)-Mesquitol (1) displayed the most potent AGE inhibitory activity. Results suggest that (-)-mesquitol (1) may serve as an important natural organic lead compound for future development of antiglycating agents along with potent antioxidant activity.

  18. Do advanced glycation end-products play a role in malaria susceptibility?

    PubMed Central

    Traoré, Karim; Arama, Charles; Médebielle, Maurice; Doumbo, Ogobara; Picot, Stéphane

    2016-01-01

    There are growing data supporting the differences in susceptibility to malaria described between sympatric populations with different lifestyles. Evidence has also been growing for some time that nutritional status and the host’s metabolism are part of the complex mechanisms underlying these differences. The role of dietary advanced glycation end-products (AGEs) in the modulation of immune responses (innate and adaptive responses) and chronic oxidative stress has been established. But less is known about AGE implication in naturally acquired immunity and susceptibility to malaria. Since inflammatory immune responses and oxidative events have been demonstrated as the hallmark of malaria infection, it seems crucial to investigate the role of AGE in susceptibility or resistance to malaria. This review provides new insight into the relationship between nutrition, metabolic disorders, and infections, and how this may influence the mechanisms of susceptibility or resistance to malaria in endemic areas. PMID:27012162

  19. Receptor for Advanced Glycation End Products (RAGE) Deficiency Attenuates the Development of Atherosclerosis in Diabetes

    PubMed Central

    Soro-Paavonen, Aino; Watson, Anna M.D.; Li, Jiaze; Paavonen, Karri; Koitka, Audrey; Calkin, Anna C.; Barit, David; Coughlan, Melinda T.; Drew, Brian G.; Lancaster, Graeme I.; Thomas, Merlin; Forbes, Josephine M.; Nawroth, Peter P.; Bierhaus, Angelika; Cooper, Mark E.; Jandeleit-Dahm, Karin A.

    2008-01-01

    OBJECTIVE—Activation of the receptor for advanced glycation end products (RAGE) in diabetic vasculature is considered to be a key mediator of atherogenesis. This study examines the effects of deletion of RAGE on the development of atherosclerosis in the diabetic apoE−/− model of accelerated atherosclerosis. RESEARCH DESIGN AND METHODS—ApoE−/− and RAGE−/−/apoE−/− double knockout mice were rendered diabetic with streptozotocin and followed for 20 weeks, at which time plaque accumulation was assessed by en face analysis. RESULTS—Although diabetic apoE−/− mice showed increased plaque accumulation (14.9 ± 1.7%), diabetic RAGE−/−/apoE−/− mice had significantly reduced atherosclerotic plaque area (4.9 ± 0.4%) to levels not significantly different from control apoE−/− mice (4.3 ± 0.4%). These beneficial effects on the vasculature were associated with attenuation of leukocyte recruitment; decreased expression of proinflammatory mediators, including the nuclear factor-κB subunit p65, VCAM-1, and MCP-1; and reduced oxidative stress, as reflected by staining for nitrotyrosine and reduced expression of various NADPH oxidase subunits, gp91phox, p47phox, and rac-1. Both RAGE and RAGE ligands, including S100A8/A9, high mobility group box 1 (HMGB1), and the advanced glycation end product (AGE) carboxymethyllysine were increased in plaques from diabetic apoE−/− mice. Furthermore, the accumulation of AGEs and other ligands to RAGE was reduced in diabetic RAGE−/−/apoE−/− mice. CONCLUSIONS—This study provides evidence for RAGE playing a central role in the development of accelerated atherosclerosis associated with diabetes. These findings emphasize the potential utility of strategies targeting RAGE activation in the prevention and treatment of diabetic macrovascular complications. PMID:18511846

  20. Regulatory mechanism of gallic acid against advanced glycation end products induced cardiac remodeling in experimental rats.

    PubMed

    Umadevi, Subramanian; Gopi, Venkatachalam; Elangovan, Vellaichamy

    2014-02-05

    Advanced glycation end products (AGEs) play a major role in the development of cardiovascular disorders in diabetic patients. Recent studies evidenced the beneficial role of phytochemicals in reducing the risk of cardiovascular diseases. Hence the present study was framed to investigate the protective role of Gallic acid (GA) on AGEs induced cardiac fibrosis. Rats were infused with in vitro prepared AGEs (50mg/kg BW-intravenous injection) for 30 days. Further, GA (25mg/kgBW) was administered to rats along with AGEs. On infusion of AGEs, induction of fibrotic markers, collagen deposition, oxidative marker NADPH oxidase (NOX-p47 phox subunit), AGE receptor (RAGE) and cytokines expression was evaluated in the heart tissues using RT-PCR, Western blot and immunostaining methods. AGEs infusion significantly (P<0.01) increased the HW/BW ratio and fibrosis (4-fold) with increased expression of matrix genes MMP-2 and -9 (P<0.01, respectively) in the heart tissues. Whereas, administration of GA along with AGEs infusion prevented the fibrosis induced by AGEs. Further, GA treatment effectively prevented the AGEs mediated up-regulation of pro-fibrotic genes and ECM proteins such as TNF-α, TGF-β, MMP-2 and -9 expression. In addition, the increased expression of NOX (P<0.01), RAGE (P<0.01), NF-κB (P<0.01) and ERK 1/2 on AGEs infusion were normalized by GA treatment. Thus the present study shows the protective effect of GA on the fibrotic response and cardiac remodeling process induced by advanced glycation end products from external sources.

  1. Advanced Glycation End Products Activate a Chymase-Dependent Angiotensin II Generating Pathway in Diabetic Complications

    PubMed Central

    Koka, Vijay; Wang, Wansheng; Huang, Xiao Ru; Kim-Mitsuyama, Shokei; Truong, Luan D.; Lan, Hui Y

    2006-01-01

    Background: Angiotensin II is a key mediator of diabetes-related vascular disease. It is now recognized that in addition to angiotensin converting enzyme (ACE), chymase is an important alternative angiotensin II generating enzyme in hypertension and diabetes. However, the mechanism of induction of chymase in diabetes remains unknown. Methods and Results: Here we report that chymase is upregulated in coronary and renal arteries in patients with diabetes by immunohistochemistry. Upregulation of vascular chymase is associated with deposition of advanced glycation end products (AGEs), increase in expression of the receptor for AGEs (RAGE), and activation of ERK1/2 MAP kinase. In vitro, AGEs can induce chymase expression and chymase-dependent angiotensin II generation in human vascular smooth muscle cells via the RAGE-ERK1/2 MAP kinase-dependent mechanism. This is confirmed by blockade of AGE-induced vascular chymase expression with a neutralizing RAGE antibody and an inhibitor to ERK1/2, and by overexpression of the dominant negative-ERK1/2. Compared to ACE, chymase contributes to the majority of angiotensin II production (more than 70%, p<0.01) in response to AGEs. Further more, AGE-induced Angiotensin II production is blocked by the anti-RAGE antibody and by inhibition of ERK1/2 MAP kinase activities. Conclusions: Advanced glycation end products, a hallmark of diabetes, induce chymase via the RAGE-ERK1/2 MAP kinase pathway. Chymase initiates an important alternative angiotensin II generating pathway in diabetes and may play a critical role in diabetic vascular disease. PMID:16520412

  2. Advanced glycation End-products (AGEs): an emerging concern for processed food industries.

    PubMed

    Sharma, Chetan; Kaur, Amarjeet; Thind, S S; Singh, Baljit; Raina, Shiveta

    2015-12-01

    The global food industry is expected to increase more than US $ 7 trillion by 2014. This rise in processed food sector shows that more and more people are diverging towards modern processed foods. As modern diets are largely heat processed, they are more prone to contain high levels of advanced glycation end products (AGEs). AGEs are a group of complex and heterogeneous compounds which are known as brown and fluorescent cross-linking substances such as pentosidine, non-fluorescent cross-linking products such as methylglyoxal-lysine dimers (MOLD), or non-fluorescent, non-cross linking adducts such as carboxymethyllysine (CML) and pyrraline (a pyrrole aldehyde). The chemistry of the AGEs formation, absorption and bioavailability and their patho-biochemistry particularly in relation to different complications like diabetes and ageing discussed. The concept of AGEs receptor - RAGE is mentioned. AGEs contribute to a variety of microvascular and macrovascular complications through the formation of cross-links between molecules in the basement membrane of the extracellular matrix and by engaging the receptor for advanced glycation end products (RAGE). Different methods of detection and quantification along with types of agents used for the treatment of AGEs are reviewed. Generally, ELISA or LC-MS methods are used for analysis of foods and body fluids, however lack of universally established method highlighted. The inhibitory effect of bioactive components on AGEs by trapping variety of chemical moieties discussed. The emerging evidence about the adverse effects of AGEs makes it necessary to investigate the different therapies to inhibit AGEs.

  3. Effects of monascin on anti-inflammation mediated by Nrf2 activation in advanced glycation end product-treated THP-1 monocytes and methylglyoxal-treated wistar rats.

    PubMed

    Lee, Bao-Hong; Hsu, Wei-Hsuan; Huang, Tao; Chang, Yu-Ying; Hsu, Ya-Wen; Pan, Tzu-Ming

    2013-02-13

    Hyperglycemia is associated with advanced glycation end products (AGEs). This study was designed to evaluate the inhibitory effects of monascin on receptor for advanced glycation end product (RAGE) signal and THP-1 monocyte inflammation after treatment with S100b, a specific ligand of RAGE. Monascin inhibited cytokine production by S100b-treated THP-1 monocytes via up-regulation of nuclear factor-erythroid 2-related factor-2 (Nrf2) and alleviated p47phox translocation to the membrane. Methylglyoxal (MG, 600 mg/kg bw) was used to induce diabetes in Wistar rats. Inhibitions of RAGE and p47phox by monascin were confirmed by peripheral blood mononuclear cells (PBMCs) of MG-induced rats. Silymarin (SM) was used as a positive control group. It was found that monascin promoted heme oxygenase-1 (HO-1) expression mediated by Nrf2. Suppressions of AGEs, tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-β) in serum of MG-induced rats were attenuated in the monascin administration group treated with retinoic acid (RA). RA treatment resulted in Nrf2 inactivation by increasing RA receptor-α (RARα) activity, suggesting that RA acts as an inhibitor of Nrf2. The results showed that monascin exerted anti-inflammatory and antioxidative effects mediated by Nrf2 to prevent the development of diseases such as type 2 diabetes caused by inflammation.

  4. PLC/CAMK IV-NF-kappaB involved in the receptor for advanced glycation end products mediated signaling pathway in human endothelial cells.

    PubMed

    You, Jie; Peng, Wei; Lin, Xu; Huang, Qing-Ling; Lin, Jian-Yin

    2010-05-14

    Advanced glycation end products (AGEs) and their interaction with the receptor for advanced glycation end products (RAGE) play an important role in diabetic vascular complications. The current study demonstrated that AGEs significantly increased RAGE expression and the release of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) in human umbilical vein endothelial cell-derived line ECV304 cells. RAGE antisense RNA partially inhibited the expression of TNF-alpha and IL-6 induced by AGEs. Oligonucleotide microarray was used to identify the genes that respond to RAGE activation. Phospholipase C beta 1 (PLC beta 1), phospholipase C beta 4 (PLC beta 4) and calcium/calmodulin-dependent protein kinase IV (CAMK IV) which associated with Ca(2+) signaling were upregulated. The rise of intracellular calcium and the NF-kappaB promoter activity induced by AGEs were suppressed by RAGE antisense RNA, PLC inhibitor U73122 and dominant negative CAMK IV, respectively. These findings suggest that PLC/CAMK IV-NF-kappaB is involved in RAGE mediated signaling pathway in human endothelial cells.

  5. Circulating advanced glycation peptides in streptozotocin-induced diabetic rats: evidence for preferential modification of IgG light chains.

    PubMed

    Gugliucci, A; Menini, T

    1998-01-01

    As the glycation/glycoxidation hypothesis for the genesis of diabetic complications is achieving widespread acceptance, much attention is being paid to the role of low molecular weight advanced glycation (AGE) adducts, as second generation glycating agents. We set out a study with the objective of attesting the presence of increased amounts of AGE-peptides in the circulation of streptozotocin-induced diabetic rats and to determine the nature of the plasma proteins which are main targets for advanced glycation. AGE (Ex 370/Em 440 nm) and pentosidine fluorescence (Ex 335/Em 385 nm) were significantly higher in plasma from diabetic rats after only one month of hyperglycemia as compared to controls (35 +/- 7 vs 25 +/- 2 AU, p< 0.05 and 54 +/- 14 vs 27 +/- 3 AU, p< 0.01 respectively). AGE-peptides (<10 kDa) were more than two-fold higher in diabetic animals. Immunoblots after SDS-PAGE of plasma proteins showed that AGE-IgG displayed a selective predominant increment in the same animals. When native rat IgG was incubated in the presence of AGE-peptides isolated from diabetic animals, AGE modification was already apparent after only 24 h of incubation, and was particularly important for light chains. AGE-immunoreactive light chains displayed an apparent increase in molecular weight. Aminoguanidine prevented, while copper enhanced AGE binding to IgG light chains. Our data validate the streptozotocin-induced diabetic rat as a model reproducing the presence of circulating AGE-peptides, give evidence that IgG are preferential targets for advanced glycation in plasma and suggest that this modification, mediated by AGE-peptides, can be prevented by aminoguanidine.

  6. Advanced glycation end products mediated cellular and molecular events in the pathology of diabetic nephropathy.

    PubMed

    Kumar Pasupulati, Anil; Chitra, P Swathi; Reddy, G Bhanuprakash

    2016-12-01

    Diabetic nephropathy (DN) is a major cause of morbidity and mortality in diabetic patients and a leading cause of end-stage renal disease (ESRD). Degenerative changes such as glomerular hypertrophy, hyperfiltration, widening of basement membranes, tubulointerstitial fibrosis, glomerulosclerosis and podocytopathy manifest in various degrees of proteinuria in DN. One of the key mechanisms implicated in the pathogenesis of DN is non-enzymatic glycation (NEG). NEG is the irreversible attachment of reducing sugars onto free amino groups of proteins by a series of events, which include the formation of Schiff's base and an Amadori product to yield advanced glycation end products (AGEs). AGE modification of client proteins from the extracellular matrix induces crosslinking, which is often associated with thickening of the basement membrane. AGEs activate several intracellular signaling cascades upon interaction with receptor for AGEs (RAGE), which manifest in aberrant cellular responses such as inflammation, apoptosis and autophagy, whereas other receptors such as AGE-R1, AGE-R3 and scavenger receptors also bind to AGEs and ensue endocytosis and degradation of AGEs. Elevated levels of both serum and tissue AGEs are associated with adverse renal outcome. Increased evidence supports that attenuation of AGE formation and/or inhibition of RAGE activation manifest(s) in improving renal function. This review provides insights of NEG, discusses the cellular and molecular events triggered by AGEs, which manifest in the pathogenesis of DN including renal fibrosis, podocyte epithelial-mesenchymal transition and activation of renin-angiotensin system. Therapies designed to target AGEs, such as inhibitors of AGEs formation and crosslink breakers, are discussed.

  7. Detection of advanced glycation end products (AGEs) on human skin by in vivo confocal Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Martin, A. A.; Pereira, L.; Ali, S. M.; Pizzol, C. D.; Tellez, C. A.; Favero, P. P.; Santos, L.; da Silva, V. V.; Praes, C. E. O.

    2016-03-01

    The aging process involves the reduction in the production of the major components of skin tissue. During intrinsic aging and photoaging processes, in dermis of human skin, fibroblasts become senescent and have decreased activity, which produce low levels of collagen. Moreover, there is accumulation of advanced glycation end products (AGEs). AGEs have incidence in the progression of age-related diseases, principally in diabetes mellitus and in Alzheimer's diseases. AGEs causes intracellular damage and/or apoptosis leading to an increase of the free radicals, generating a crosslink with skin proteins and oxidative stress. The aim of this study is to detect AGEs markers on human skin by in vivo Confocal Raman spectroscopy. Spectra were obtained by using a Rivers Diagnostic System, 785 nm laser excitation and a CCD detector from the skin surface down to 120 μm depth. We analyzed the confocal Raman spectra of the skin dermis of 30 women volunteers divided into 3 groups: 10 volunteers with diabetes mellitus type II, 65-80 years old (DEW); 10 young healthy women, 20-33 years old (HYW); and 10 elderly healthy women, 65-80 years old (HEW). Pentosidine and glucosepane were the principally identified AGEs in the hydroxyproline and proline Raman spectral region (1000-800 cm-1), in the 1.260-1.320 cm-1 region assignable to alpha-helical amide III modes, and in the Amide I region. Pentosidine and glucosepane calculated vibrational spectra were performed through Density Functional Theory using the B3LYP functional with 3-21G basis set. Difference between the Raman spectra of diabetic elderly women and healthy young women, and between healthy elderly women and healthy young women were also obtained with the purpose of identifying AGEs Raman bands markers. AGEs peaks and collagen changes have been identified and used to quantify the glycation process in human skin.

  8. Aging induces cardiac diastolic dysfunction, oxidative stress, accumulation of advanced glycation endproducts and protein modification.

    PubMed

    Li, Shi-Yan; Du, Min; Dolence, E Kurt; Fang, Cindy X; Mayer, Gabriele E; Ceylan-Isik, Asli F; LaCour, Karissa H; Yang, Xiaoping; Wilbert, Christopher J; Sreejayan, Nair; Ren, Jun

    2005-04-01

    Evidence suggests that aging, per se, is a major risk factor for cardiac dysfunction. Oxidative modification of cardiac proteins by non-enzymatic glycation, i.e. advanced glycation endproducts (AGEs), has been implicated as a causal factor in the aging process. This study was designed to examine the role of aging on cardiomyocyte contractile function, cardiac protein oxidation and oxidative modification. Mechanical properties were evaluated in ventricular myocytes from young (2-month) and aged (24-26-month) mice using a MyoCam system. The mechanical indices evaluated were peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90) and maximal velocity of shortening/relengthening (+/- dL/dt). Oxidative stress and protein damage were evaluated by glutathione and glutathione disulfide (GSH/GSSG) ratio and protein carbonyl content, respectively. Activation of NAD(P)H oxidase was determined by immunoblotting. Aged myocytes displayed a larger cell cross-sectional area, prolonged TR90, and normal PS, +/- dL/dt and TPS compared with young myocytes. Aged myocytes were less tolerant of high stimulus frequency (from 0.1 to 5 Hz) compared with young myocytes. Oxidative stress and protein oxidative damage were both elevated in the aging group associated with significantly enhanced p47phox but not gp91phox expression. In addition, level of cardiac AGEs was approximately 2.5-fold higher in aged hearts than young ones determined by AGEs-ELISA. A group of proteins with a molecular range between 50 and 75 kDa with pI of 4-7 was distinctively modified in aged heart using one- or two-dimension SDS gel electrophoresis analysis. These data demonstrate cardiac diastolic dysfunction and reduced stress tolerance in aged cardiac myocytes, which may be associated with enhanced cardiac oxidative damage, level of AGEs and protein modification by AGEs.

  9. Comparative LC-MS/MS profiling of free and protein-bound early and advanced glycation-induced lysine modifications in dairy products.

    PubMed

    Hegele, Jörg; Buetler, Timo; Delatour, Thierry

    2008-06-09

    Free and protein-bound forms of early and advanced glycation-induced lysine (Lys) modifications were quantified in dairy products by LC-MS/MS using a stable isotope dilution assay. The glycation profiles for N(epsilon)-fructoselysine (FL), N(epsilon)-carboxymethyllysine (CML) and pyrraline (Pyr) were monitored in raw and processed cow milk to investigate whether free glycation products could serve as fast and simple markers to assess the extent of protein glycation in dairy products. In all milk samples, the fraction of free glycation adducts was predominantly composed of advanced modifications, e.g. 8.34+/-3.81 nmol CML per micromol of free Lys (Lys(free)) and 81.5+/-87.8 nmol Pyr micromol(-1) Lys(free)(-1) vs. 3.72+/-1.29 nmol FL micromol(-1) Lys(free)(-1). In contrast, the protein-bound early glycation product FL considerably outweighed the content of CML and Pyr in milk proteins of raw and processed cow milk, whereas severely heat treated milk products, e.g. condensed milk, contained a higher amount of protein-bound advanced glycation adducts. Typical values recorded for milk samples processed under mild conditions were 0.47+/-0.08 nmol FL micromol(-1) of protein-bound Lys (Lys(p-b)), 0.04+/-0.03 nmol CML micromol(-1) Lys(p-b)(-1) and 0.06+/-0.02 nmol Pyr micromol(-1)Lys(p-b)(-1). It was particularly noticeable, however, that mild heat treatment of raw milk, i.e. pasteurization and UHT treatment, did not significantly increase the amount of both free and protein-bound Lys modifications. In conclusion, the profiles of free and protein-bound glycation-induced Lys modifications were found to be different and a screening of free glycation adducts does, therefore, not allow for a conclusion about the protein glycation status of dairy products.

  10. Ability of resveratrol to inhibit advanced glycation end product formation and carbohydrate-hydrolyzing enzyme activity, and to conjugate methylglyoxal.

    PubMed

    Shen, Yixiao; Xu, Zhimin; Sheng, Zhanwu

    2017-02-01

    Glycation can generate advanced glycation end products (AGE) and its intermediates methylglyoxal (MGO) and glyoxal in foods, which increase the risk of developing diabetes diseases. In this study, the effect of resveratrol against AGE formation, carbohydrate-hydrolyzing enzyme activity and trapping MGO capability were evaluated. Resveratrol showed a significant inhibition capability against AGE formation in bovine serum albumin (BSA)-fructose, BSA-MGO and arginine-MGO models with inhibition percentages of 57.94, 85.95 and 99.35%, respectively. Furthermore, resveratrol acted as a competitive inhibitor for α-amylase with IC50 3.62μg/ml, while it behaved in an uncompetitive manner for α-glucosidase with an IC50 of 17.54μg/l. A prevention of BSA protein glycation was observed in the BSA-fructose model with addition of resveratrol. Three types of resveratrol-MGO adducts were identified in the model consisting of MGO and resveratrol. The results demonstrated that resveratrol has potential in reducing glycation in foods and retarding carbohydrate-hydrolyzing enzyme activities.

  11. Potential Dual Role of Eugenol in Inhibiting Advanced Glycation End Products in Diabetes: Proteomic and Mechanistic Insights

    PubMed Central

    Singh, Priyanka; Jayaramaiah, Ramesha H.; Agawane, Sachin B.; Vannuruswamy, Garikapati; Korwar, Arvind M.; Anand, Atul; Dhaygude, Vitthal S.; Shaikh, Mahemud L.; Joshi, Rakesh S.; Boppana, Ramanamurthy; Kulkarni, Mahesh J.; Thulasiram, Hirekodathakallu V.; Giri, Ashok P.

    2016-01-01

    Medicinally important genus Ocimum harbors a vast pool of chemically diverse metabolites. Current study aims at identifying anti-diabetic candidate compounds from Ocimum species. Major metabolites in O. kilimandscharicum, O. tenuiflorum, O. gratissimum were purified, characterized and evaluated for anti-glycation activity. In vitro inhibition of advanced glycation end products (AGEs) by eugenol was found to be highest. Preliminary biophysical analysis and blind docking studies to understand eugenol-albumin interaction indicated eugenol to possess strong binding affinity for surface exposed lysines. However, binding of eugenol to bovine serum albumin (BSA) did not result in significant change in secondary structure of protein. In vivo diabetic mice model studies with eugenol showed reduction in blood glucose levels by 38% likely due to inhibition of α-glucosidase while insulin and glycated hemoglobin levels remain unchanged. Western blotting using anti-AGE antibody and mass spectrometry detected notably fewer AGE modified peptides upon eugenol treatment both in vivo and in vitro. Histopathological examination revealed comparatively lesser lesions in eugenol-treated mice. Thus, we propose eugenol has dual mode of action in combating diabetes; it lowers blood glucose by inhibiting α-glucosidase and prevents AGE formation by binding to ε-amine group on lysine, protecting it from glycation, offering potential use in diabetic management. PMID:26739611

  12. Potential Dual Role of Eugenol in Inhibiting Advanced Glycation End Products in Diabetes: Proteomic and Mechanistic Insights.

    PubMed

    Singh, Priyanka; Jayaramaiah, Ramesha H; Agawane, Sachin B; Vannuruswamy, Garikapati; Korwar, Arvind M; Anand, Atul; Dhaygude, Vitthal S; Shaikh, Mahemud L; Joshi, Rakesh S; Boppana, Ramanamurthy; Kulkarni, Mahesh J; Thulasiram, Hirekodathakallu V; Giri, Ashok P

    2016-01-07

    Medicinally important genus Ocimum harbors a vast pool of chemically diverse metabolites. Current study aims at identifying anti-diabetic candidate compounds from Ocimum species. Major metabolites in O. kilimandscharicum, O. tenuiflorum, O. gratissimum were purified, characterized and evaluated for anti-glycation activity. In vitro inhibition of advanced glycation end products (AGEs) by eugenol was found to be highest. Preliminary biophysical analysis and blind docking studies to understand eugenol-albumin interaction indicated eugenol to possess strong binding affinity for surface exposed lysines. However, binding of eugenol to bovine serum albumin (BSA) did not result in significant change in secondary structure of protein. In vivo diabetic mice model studies with eugenol showed reduction in blood glucose levels by 38% likely due to inhibition of α-glucosidase while insulin and glycated hemoglobin levels remain unchanged. Western blotting using anti-AGE antibody and mass spectrometry detected notably fewer AGE modified peptides upon eugenol treatment both in vivo and in vitro. Histopathological examination revealed comparatively lesser lesions in eugenol-treated mice. Thus, we propose eugenol has dual mode of action in combating diabetes; it lowers blood glucose by inhibiting α-glucosidase and prevents AGE formation by binding to ε-amine group on lysine, protecting it from glycation, offering potential use in diabetic management.

  13. Activation of the Receptor for Advanced Glycation End Products System in Women with Severe Preeclampsia

    PubMed Central

    Oliver, Emily A.; Buhimschi, Catalin S.; Dulay, Antonette T.; Baumbusch, Margaret A.; Abdel-Razeq, Sonya S.; Lee, Sarah Y.; Zhao, Guomao; Jing, Shichu; Pettker, Christian M.

    2011-01-01

    Context: Activation of the receptor for advanced glycation end products (RAGE) mediates cellular injury. Soluble forms of RAGE [soluble RAGE (sRAGE), endogenous secretory (esRAGE)] bind RAGE ligands, thereby preventing downstream signaling and damage. Objectives: The objective of the study was to characterize the changes in maternal serum, amniotic fluid, and cord blood soluble receptor for advanced glycation end products (sRAGE) during physiological gestation and to provide insight into mechanisms responsible for RAGE activation in preeclampsia. Design and Settings: This was a cross-sectional study at a tertiary university hospital. Patients: We studied 135 women in the following groups: nonpregnant controls (n = 16), healthy pregnant controls (n = 68), pregnant women with chronic hypertension (n = 13), or pregnant women with severe preeclampsia (sPE; n = 38). Interventions and Main Outcome Measures: sRAGE and esRAGE levels were evaluated in vivo by ELISA in maternal serum, amniotic fluid, and cord blood and in vitro after stimulation of the amniochorion and placental explants with lipopolysaccharide or xanthine/xanthine oxidase. Placenta and amniochorion were immunostained for RAGE. Real-time quantitative PCR measured RAGE mRNA. Results: Pregnant women had significantly decreased serum sRAGE compared with nonpregnant subjects (P < 0.001). sPE women had higher serum and amniotic fluid sRAGE and esRAGE relative to those expected for gestational age (P < 0.001). Cord blood sRAGE remained unaffected by sPE. RAGE immunoreactivity and mRNA expression appeared elevated in the amniochorion of sPE women. Xanthine/xanthine oxidase (but not lipopolysaccharide) significantly up-regulated the release of sRAGE (P < 0.001) in the amniochorion explant system. Conclusions: Fetal membranes are a rich source of sRAGE. Elevated maternal serum and amniotic fluid sRAGE and esRAGE, paralleled by increased RAGE expression in the amniochorion, suggest activation of this system in s

  14. Beneficial effect of Corni Fructus, a constituent of Hachimi-jio-gan, on advanced glycation end-product-mediated renal injury in Streptozotocin-treated diabetic rats.

    PubMed

    Yamabe, Noriko; Kang, Ki Sung; Goto, Eiko; Tanaka, Takashi; Yokozawa, Takako

    2007-03-01

    Previous investigations have demonstrated that Hachimi-jio-gan, a Chinese prescription consisting of eight crude drugs, has a therapeutic potential in diabetes and diabetic nephropathy, using these model rats. To add to these findings, we performed this study to assess whether one of the crude drugs, Corni Fructus (Cornus officinalis SIEB. et ZUCC.), had an effect on streptozotocin-induced diabetic rats as a major active constituent, compared with an inhibitor of advanced glycation end-product (AGE) formation, aminoguanidine. Diabetic rats were orally administrated Corni Fructus extract (50, 100, 200 mg/kg body weight/d) or aminoguanidine (100 mg/kg body weight/d). Treatment with Corni Fructus for 10 d suppressed hyperglycemia, proteinuria, renal AGE formation, and related protein expressions, i.e., receptor for AGEs, nuclear factor-kappaB, transforming growth factor-beta1, and Nepsilon-(carboxymethyl)lysine, in the same way as with aminoguanidine. However, improvement of renal function, shown via serum creatinine (Cr) and Cr clearance, was superior to aminoguanidine treatment. In conclusion, the present study supported the hypothesis that Corni Fructus plays an important role against diabetic pathogenesis, i.e., reducing glucose toxicities, up-regulating renal function, and consequently ameliorating glycation-associated renal damage; thus, this study may provide a new recognition of crude drugs to clarify the mechanisms of Chinese prescriptions.

  15. Effects of plant-derived polyphenols on TNF-alpha and nitric oxide production induced by advanced glycation endproducts.

    PubMed

    Chandler, Dave; Woldu, Ameha; Rahmadi, Anton; Shanmugam, Kirubakaran; Steiner, Nicole; Wright, Elise; Benavente-García, Obdulio; Schulz, Oliver; Castillo, Julián; Münch, Gerald

    2010-07-01

    Advanced glycation endproducts (AGEs) accumulate on protein deposits including the beta-amyloid plaques in Alzheimer's disease. AGEs interact with the "receptor for advanced glycation endproducts", and transmit their signals using intracellular reactive oxygen species as second messengers. Ultimately, AGEs induce the expression of a variety of pro-inflammatory markers including the tumor necrosis factor (TNF-alpha) and inducible nitric oxide (NO) synthase. Antioxidants that act intracellularly, including polyphenols, have been shown to scavenge these "signaling" reactive oxygen species, and thus perform in an anti-inflammatory capacity. This study tested the pure compounds apigenin and diosmetin as well as extracts from silymarin, uva ursi (bearberry) and green olive leaf for their ability to attenuate AGE-induced NO and TNF-alpha production. All five tested samples inhibited BSA-AGE-induced NO production in a dose-dependent manner. Apigenin and diosmetin were most potent, and exhibited EC(50) values approximately 10 microM. In contrast, TNF-alpha expression was only reduced by apigenin, diosmetin and silymarin; not by the bearberry and green olive leaf extracts. In addition, the silymarin and bearberry extracts caused significant cell death at concentrations >or=10 microg/mL and >or=50 microg/mL, respectively. In conclusion, we suggest that plant-derived polyphenols might offer therapeutic opportunities to delay the progression of AGE-mediated and receptor for advanced glycation endproducts-mediated neuro-inflammatory diseases including Alzheimer's disease.

  16. Advanced Glycation End-Products Induce Apoptosis of Vascular Smooth Muscle Cells: A Mechanism for Vascular Calcification

    PubMed Central

    Koike, Sayo; Yano, Shozo; Tanaka, Sayuri; Sheikh, Abdullah M.; Nagai, Atsushi; Sugimoto, Toshitsugu

    2016-01-01

    Vascular calcification, especially medial artery calcification, is associated with cardiovascular death in patients with diabetes mellitus and chronic kidney disease (CKD). To determine the underlying mechanism of vascular calcification, we have demonstrated in our previous report that advanced glycation end-products (AGEs) stimulated calcium deposition in vascular smooth muscle cells (VSMCs) through excessive oxidative stress and phenotypic transition into osteoblastic cells. Since AGEs can induce apoptosis, in this study we investigated its role on VSMC apoptosis, focusing mainly on the underlying mechanisms. A rat VSMC line (A7r5) was cultured, and treated with glycolaldehyde-derived AGE-bovine serum albumin (AGE3-BSA). Apoptotic cells were identified by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. To quantify apoptosis, an enzyme-linked immunosorbent assay (ELISA) for histone-complexed DNA fragments was employed. Real-time PCR was performed to determine the mRNA levels. Treatment of A7r5 cells with AGE3-BSA from 100 µg/mL concentration markedly increased apoptosis, which was suppressed by Nox inhibitors. AGE3-BSA significantly increased the mRNA expression of NAD(P)H oxidase components including Nox4 and p22phox, and these findings were confirmed by protein levels using immunofluorescence. Dihydroethidisum assay showed that compared with cBSA, AGE3-BSA increased reactive oxygen species level in A7r5 cells. Furthermore, AGE3-induced apoptosis was significantly inhibited by siRNA-mediated knockdown of Nox4 or p22phox. Double knockdown of Nox4 and p22phox showed a similar inhibitory effect on apoptosis as single gene silencing. Thus, our results demonstrated that NAD(P)H oxidase-derived oxidative stress are involved in AGEs-induced apoptosis of VSMCs. These findings might be important to understand the pathogenesis of vascular calcification in diabetes and CKD. PMID:27649164

  17. Pentosidine in advanced glycation end-products (AGEs) during UVA irradiation generates active oxygen species and impairs human dermal fibroblasts.

    PubMed

    Okano, Y; Masaki, H; Sakurai, H

    2001-08-01

    Our previous study reported that advanced glycation end-products (AGE)-modified BSA produced active oxygen species, *O2-, H2O2, and *OH under UVA irradiation and enhanced the cytotoxicity of UVA light. We examined whether pentosidine in AGE-modified BSA was involved in one of the mechanisms generating the active oxygen species. In biological investigations, fibroblasts exposed to UVA (20 J/cm2) in the presence of pentosidine-rich compounds (PRCs), which were prepared with L-arginine, L-lysine and glucose, showed a time-dependent leakage of the cytosolic enzyme LDH. In addition, release of LDH was suppressed by addition of DMSO and deferoxamine under UVA irradiation. From these results, it was determined that PRCs exposed to UVA damaged the plasma membrane of human dermal fibroblasts due to the conversion of *OH from H2O2 via a Fenton-like reaction. These features of PRCs exposed to UVA were consistent with those of AGE-modified BSA. In an ESR study, PRCs under UVA irradiation yielded DMPO-OH (DMPO-OH adduct) using DMPO as a spin-trapping reagent. *O2- generation from UVA-irradiated PRCs was also indicated by the combination of NBT reduction and SOD. When PRCs were exposed to UVA light controlled with a long-pass filter, WG-360, it was found that their production of *O2- was prohibited less than 50% in the NBT reduction assay. The *O2- production profile of PRCs depending on the wavelength of UVA light was similar to that of AGE-modified BSA. Furthermore, it was found that the H2O2 level was increased by PRCs exposed to UVA. These results indicated that pentosidine is an important factor of AGE-modified BSA in active oxygen generation under UVA irradiation.

  18. Soluble Receptor for Advanced Glycation End Products Improves Stromal Cell–Derived Factor-1 Activity in Model Diabetic Environments

    PubMed Central

    Olekson, Melissa Przyborowski; Faulknor, Renea A.; Hsia, Henry C.; Schmidt, Ann Marie; Berthiaume, François

    2016-01-01

    Objective: In diabetes, hyperglycemia causes the accumulation of advanced glycation end products (AGEs) that trigger reactive oxygen species (ROS) generation through binding the receptor for AGEs (RAGE). Because exogenous growth factors have had little success in enhancing chronic wound healing, we investigated whether hyperglycemia-induced AGEs interfere with cellular responses to extracellular signals. We used stromal cell–derived factor-1 (SDF-1), an angiogenic chemokine also known to promote stem cell recruitment in skin wounds. Approach: Human leukemia-60 (HL-60) cells and mouse peripheral blood mononuclear cells (PBMCs), which express the SDF-1 receptor CXCR-4, were incubated for 24 h in medium supplemented with 25 mM d-glucose. Soluble RAGE (sRAGE) was used to block RAGE activation. Response to SDF-1 was measured in cellular migration and ROS assays. A diabetic murine excisional wound model measured SDF-1 liposome and sRAGE activity in vivo. Results: Hyperglycemia led to significant accumulation of AGEs, decreased SDF-1–directed migration, and elevated baseline ROS levels; it suppressed the ROS spike normally triggered by SDF-1. sRAGE decreased the ROS baseline and restored both the SDF-1–mediated spike and cell migration. Topically applied sRAGE alone promoted healing and enhanced the effect of exogenous SDF-1 on diabetic murine wounds. Innovation: While there is interest in using growth factors to improve wound healing, this strategy is largely ineffective in diabetic wounds. We show that sRAGE may restore signaling, thus potentiating the effect of exogenously applied growth factors. Conclusion: Blocking RAGE with sRAGE restores SDF-1–mediated cellular responses in hyperglycemic environments and may potentiate the effectiveness of SDF-1 applied in vivo. PMID:28078186

  19. Limited role of the receptor for advanced glycation end products during Streptococcus pneumoniae bacteremia.

    PubMed

    Achouiti, Ahmed; de Vos, Alex F; de Beer, Regina; Florquin, Sandrine; van 't Veer, Cornelis; van der Poll, Tom

    2013-01-01

    Streptococcus pneumoniae is one of the most common causes of sepsis. Sepsis is associated with the release of 'damage-associated molecular patterns' (DAMPs). The receptor for advanced glycation end products (RAGE) is a multiligand receptor, abundantly expressed in the lungs, that recognizes several of these DAMPs. Triggering of RAGE leads to activation of the NF-κB pathway and perpetuation of inflammation. Earlier investigations have shown that the absence of RAGE reduces inflammation and bacterial dissemination and increases survival in sepsis caused by S. pneumoniae pneumonia. We hypothesized that the detrimental role of RAGE depends on the level of RAGE expression in the primary organ of infection. By directly injecting S. pneumoniae intravenously, thereby circumventing the extensive RAGE-expressing lung, we here determined whether RAGE contributes to an adverse outcome of bacteremia or whether its role is restricted to primary lung infection. During late-stage infection (48 h), rage(-/-) mice had an attenuated systemic inflammatory response, as reflected by lower plasma levels of proinflammatory cytokines, reduced endothelial cell activation (as measured by E-selectin levels) and less neutrophil accumulation in lung tissue. However, RAGE deficiency did not influence bacterial loads or survival in this model. In accordance, plasma markers for cell injury were similar in both mouse strains. These results demonstrate that while RAGE plays a harmful part in S. pneumoniae sepsis originating from the respiratory tract, this receptor has a limited role in the outcome of primary bloodstream infection by this pathogen.

  20. Receptor for advanced glycation end products is protective during murine tuberculosis.

    PubMed

    van Zoelen, Marieke A D; Wieland, Catharina W; van der Windt, Gerritje J W; Florquin, Sandrine; Nawroth, Peter P; Bierhaus, Angelika; van der Poll, Tom

    2012-10-01

    The development of active tuberculosis after infection with Mycobacterium tuberculosis is almost invariably associated with a persistent or transient state of relative immunodeficiency. The receptor for advanced glycation end products (RAGE) is a promiscuous receptor that is involved in pulmonary inflammation and infection. To investigate the role of RAGE in tuberculosis, we intranasally infected wild-type (Wt) and RAGE deficient (RAGE(-/-)) mice with live virulent M. tuberculosis. While lungs of uninfected Wt mice expressed RAGE, in particular on endothelium, M. tuberculosis pneumonia was associated with an enhanced pulmonary expression of RAGE. Lung inflammation was increased in RAGE(-/-) mice, as indicated by histopathology, percentage of inflamed area, lung weight and cytokine and chemokine levels. In addition, lung lymphocyte and neutrophil numbers were increased in the RAGE(-/-) mice. RAGE(-/-) mice had modestly higher mycobacterial loads in the lungs after 3 weeks but not after 6 weeks of infection. Moreover, RAGE(-/-) mice displayed more body weight loss and enhanced mortality. In summary, pulmonary RAGE expression is increased during tuberculosis. In addition, these data suggest that RAGE plays a beneficial role in the host response to pulmonary tuberculosis.

  1. Advanced glycation end products facilitate bacterial adherence in urinary tract infection in diabetic mice.

    PubMed

    Ozer, Ahmet; Altuntas, Cengiz Z; Izgi, Kenan; Bicer, Fuat; Hultgren, Scott J; Liu, Guiming; Daneshgari, Firouz

    2015-07-01

    Diabetic individuals have increased susceptibility to urinary tract infection (UTI), a common, painful condition. During diabetes mellitus, non-enzymatic reactions between reducing sugars and protein amine groups result in excessive production of advanced glycation end products (AGEs) that accumulate in tissues. Since bacteria adhere to cell surfaces by binding to carbohydrates, we hypothesized that adherence of bacteria to the bladder in diabetics may be enhanced by accumulation of AGEs on urothelial surface proteins. Using a murine model of UTI, we observed increased adherence of type 1 fimbriated uropathogenic Escherichia coli (UPEC) to the bladder in streptozotocin-induced diabetic female mice compared with age-matched controls, along with increased concentrations of two common AGEs in superficial urothelial cells from diabetic bladders. Several lectins with different specificities exhibited increased binding to urothelial homogenates from diabetic mice compared with controls, and two of those lectins also bound to AGEs. Furthermore, mannose-binding type 1 fimbriae isolated from UPEC bound to different AGEs, and UPEC adherence to the bladder in diabetic mice, were inhibited by pretreatment of mice with the AGE inhibitor pyridoxamine. These results strongly suggest a role for urothelial AGE accumulation in increased bacterial adherence during UTI in diabetes.

  2. Receptor for Advanced Glycation End Products (RAGE) Serves a Protective Role during Klebsiella pneumoniae - Induced Pneumonia.

    PubMed

    Achouiti, Ahmed; de Vos, Alex F; van 't Veer, Cornelis; Florquin, Sandrine; Tanck, Michael W; Nawroth, Peter P; Bierhaus, Angelika; van der Poll, Tom; van Zoelen, Marieke A D

    2016-01-01

    Klebsiella species is the second most commonly isolated gram-negative organism in sepsis and a frequent causative pathogen in pneumonia. The receptor for advanced glycation end products (RAGE) is expressed on different cell types and plays a key role in diverse inflammatory responses. We here aimed to investigate the role of RAGE in the host response to Klebsiella (K.) pneumoniae pneumonia and intransally inoculated rage gene deficient (RAGE-/-) and normal wild-type (Wt) mice with K. pneumoniae. Klebsiella pneumonia resulted in an increased pulmonary expression of RAGE. Furthermore, the high-affinity RAGE ligand high mobility group box-1 was upregulated during K. pneumoniae pneumonia. RAGE deficiency impaired host defense as reflected by a worsened survival, increased bacterial outgrowth and dissemination in RAGE-/- mice. RAGE-/- neutrophils showed a diminished phagocytosing capacity of live K. pneumoniae in vitro. Relative to Wt mice, RAGE-/- mice demonstrated similar lung inflammation, and slightly elevated-if any-cytokine and chemokine levels and unchanged hepatocellular injury. In addition, RAGE-/- mice displayed an unaltered response to intranasally instilled Klebsiella lipopolysaccharide (LPS) with respect to pulmonary cell recruitment and local release of cytokines and chemokines. These data suggest that (endogenous) RAGE protects against K. pneumoniae pneumonia. Also, they demonstrate that RAGE contributes to an effective antibacterial defense during K. pneumoniae pneumonia, at least partly via its participation in the phagocytic properties of professional granulocytes. Additionally, our results indicate that RAGE is not essential for the induction of a local and systemic inflammatory response to either intact Klebsiella or Klebsiella LPS.

  3. Short-term effects of dietary advanced glycation end products in rats.

    PubMed

    Poulsen, Malene W; Andersen, Jeanette M; Hedegaard, Rikke V; Madsen, Andreas N; Krath, Britta N; Monošík, Rastislav; Bak, Monika J; Nielsen, John; Holst, Birgitte; Skibsted, Leif H; Larsen, Lesli H; Dragsted, Lars O

    2016-02-28

    Dietary advanced glycation end products (AGE) formed during heating of food have gained interest as potential nutritional toxins with adverse effects on inflammation and glucose metabolism. In the present study, we investigated the short-term effects of high and low molecular weight (HMW and LMW) dietary AGE on insulin sensitivity, expression of the receptor for AGE (RAGE), the AGE receptor 1 (AGER1) and TNF-α, F2-isoprostaglandins, body composition and food intake. For 2 weeks, thirty-six Sprague-Dawley rats were fed a diet containing 20% milk powder with different proportions of this being given as heated milk powder (0, 40 or 100%), either native (HMW) or hydrolysed (LMW). Gene expression of RAGE and AGER1 in whole blood increased in the group receiving a high AGE LMW diet, which also had the highest urinary excretion of the AGE, methylglyoxal-derived hydroimidazolone 1 (MG-H1). Urinary excretion of N ε-carboxymethyl-lysine increased with increasing proportion of heat-treated milk powder in the HMW and LMW diets but was unrelated to gene expression. There was no difference in insulin sensitivity, F2-isoprostaglandins, food intake, water intake, body weight or body composition between the groups. In conclusion, RAGE and AGER1 expression can be influenced by a high AGE diet after only 2 weeks in proportion to MG-H1 excretion. No other short-term effects were observed.

  4. Quercetin inhibits advanced glycation end product formation by trapping methylglyoxal and glyoxal.

    PubMed

    Li, Xiaoming; Zheng, Tiesong; Sang, Shengmin; Lv, Lishuang

    2014-12-17

    Methylglyoxal (MGO) and glyoxal (GO) not only are endogenous metabolites but also exist in exogenous resources, such as foods, beverages, urban atmosphere, and cigarette smoke. They have been identified as reactive dicarbonyl precursors of advanced glycation end products (AGEs), which have been associated with diabetes-related long-term complications. In this study, quercetin, a natural flavonol found in fruits, vegetables, leaves, and grains, could effectively inhibit the formation of AGEs in a dose-dependent manner via trapping reactive dicarbonyl compounds. More than 50.5% of GO and 80.1% of MGO were trapped at the same time by quercetin within 1 h under physiological conditions. Quercetin and MGO (or GO) were combined at different ratios, and the products generated from this reaction were analyzed with LC-MS. Both mono-MGO and di-MGO adducts of quercetin were detected in this assay using LC-MS, but only tiny amounts of mono-GO adducts of quercetin were found. Additionally, di-MGO adducts were observed as the dominant product with prolonged incubation time. In the bovine serum albumin (BSA)-MGO/GO system, quercetin traps MGO and GO directly and then significantly inhibits the formation of AGEs.

  5. Age-Related Effects of Advanced Glycation End Products (Ages) in Bone Matrix on Osteoclastic Resorption.

    PubMed

    Yang, Xiao; Gandhi, Chintan; Rahman, Md Mizanur; Appleford, Mark; Sun, Lian-Wen; Wang, Xiaodu

    2015-12-01

    Advanced glycation end products (AGEs) accumulate in bone extracellular matrix as people age. Previous studies have shown controversial results regarding the role of in situ AGEs accumulation in osteoclastic resorption. To address this issue, this study cultured human osteoclast cells directly on human cadaveric bone slices from different age groups (young and elderly) to warrant its relevance to in vivo conditions. The cell culture was terminated on the 3rd, 7th, and 10th day, respectively, to assess temporal changes in the number of differentiated osteoclasts, the number and size of osteoclastic resorption pits, the amount of bone resorbed, as well as the amount of matrix AGEs released in the medium by resorption. In addition, the in situ concentration of matrix AGEs at each resorption pit was also estimated based on its AGEs autofluorescent intensity. The results indicated that (1) osteoclastic resorption activities were significantly correlated with the donor age, showing larger but shallower resorption pits on the elderly bone substrates than on the younger ones; (2) osteoclast resorption activities were not significantly dependent on the in situ AGEs concentration in bone matrix, and (3) a correlation was observed between osteoclast activities and the concentration of AGEs released by the resorption. These results suggest that osteoclasts tend to migrate away from initial anchoring sites on elderly bone substrate during resorption compared to younger bone substrates. However, such behavior is not directly related to the in situ concentration of AGEs in bone matrix at the resorption sites.

  6. Role of advanced glycation end-products in obesity-related ovarian dysfunction.

    PubMed

    Merhi, Z; Mcgee, E A; Buyuk, E

    2014-09-01

    Obesity affects ovarian function, one of the main regulators of female fertility. Tissue levels of the proinflammatory advanced glycation end-products (AGEs) and their receptors (RAGE) are elevated in obesity. AGEs are key contributors to perturbations in the ovarian microenvironment. On this basis, the present review focuses on clinical and experimental studies supporting the role of AGE-RAGE system as a contributor to obesity-related ovarian dysfunction. Particular emphasis has been given to changes in AGEs, RAGE and the anti-inflammatory soluble receptor (sRAGE) levels in obesity state and following dietary interventions (high-fat diet and weight loss). Ovarian sensitivity, in particular granulosa cell function and oocyte meiosis, to the pro-inflammatory AGE-RAGE system as well as the relationship of follicular fluid AGEs and sRAGE to in vitro fertilization outcome are also discussed. Overall, obesity, with its alterations in the AGE-RAGE system, can disrupt the ovarian microenvironment potentially compromising oocyte competence and fertility. This review underscores a critical need to uncover the mechanistic actions of AGE-RAGE system in obesity-related ovarian dysfunction. Clinical and basic studies focusing on elucidating the patterns of accumulation and role of the AGE-RAGE system in human ovarian follicles are key steps in understanding their contribution to the health of human oocytes and embryos.

  7. Advanced glycation end products (AGEs) and their receptor (RAGE) induce apoptosis of periodontal ligament fibroblasts.

    PubMed

    Li, D X; Deng, T Z; Lv, J; Ke, J

    2014-12-01

    Diabetics have an increased prevalence of periodontitis, and diabetes is one of the causative factors of severe periodontitis. Apoptosis is thought to be involved in this pathogenic relationship. The aim of this study was to investigate apoptosis in human periodontal ligament (PDL) fibroblasts induced by advanced glycation end products (AGEs) and their receptor (RAGE). We examined the roles of apoptosis, AGEs, and RAGE during periodontitis in diabetes mellitus using cultured PDL fibroblasts that were treated by AGE-modified bovine serum albumin (AGE-BSA), bovine serum albumin (BSA) alone, or given no treatment (control). Microscopy and real-time quantitative PCR indicated that PDL fibroblasts treated with AGE-BSA were deformed and expressed higher levels of RAGE and caspase 3. Cell viability assays and flow cytometry indicated that AGE-BSA reduced cell viability (69.80 ± 5.50%, P<0.01) and increased apoptosis (11.31 ± 1.73%, P<0.05). Hoechst 33258 staining and terminal-deoxynucleotidyl transferase-mediated nick-end labeling revealed that AGE-BSA significantly increased apoptosis of PDL fibroblasts. The results showed that the changes in PDL fibroblasts induced by AGE-BSA may explain how AGE-RAGE participates in and exacerbates periodontium destruction.

  8. Advanced Glycation End Products: Link between Diet and Ovulatory Dysfunction in PCOS?

    PubMed

    Garg, Deepika; Merhi, Zaher

    2015-12-04

    PCOS is the most common cause of anovulation in reproductive-aged women with 70% experiencing ovulatory problems. Advanced glycation end products are highly reactive molecules that are formed by non-enzymatic reactions of sugars with proteins, nucleic acids and lipids. AGEs are also present in a variety of diet where substantial increase in AGEs can result due to thermal processing and modifications of food. Elevation in bodily AGEs, produced endogenously or absorbed exogenously from high-AGE diets, is further exaggerated in women with PCOS and is associated with ovulatory dysfunction. Additionally, increased expression of AGEs as pro-inflammatory receptors in the ovarian tissue has been observed in women with PCOS. In this review, we summarize the role of dietary AGEs as mediators of metabolic and reproductive alterations in PCOS. Once a mechanistic understanding of the relationship between AGEs and anovulation is established, there is a promise that such knowledge will contribute to the subsequent development of targeted pharmacological therapies that will treat anovulation and improve ovarian health in women with PCOS.

  9. Generation and characterization of antibodies against arginine-derived advanced glycation endproducts.

    PubMed

    Wang, Tina; Streeter, Matthew D; Spiegel, David A

    2015-11-01

    Although antibodies reagents have been widely employed for studying advanced glycation end-products (AGEs), these materials have been produced using complex mixtures of immunogens. Consequently, their epitope specificity remains unknown. Here we have generated the first antibodies capable of recognizing each of the three isomers of the methylglyoxal hydroimidazolones (MG-Hs) by using chemical synthesis to create homogenous immunogens. Furthermore, we have thoroughly characterized the epitope specificity of both our antibodies and that of two existing monoclonals by implementing a direct ELISA protocol employing synthetic MG-H antigens. Finally, we employed the reported anti-MG-H antibodies to the detection of MG-Hs in cellular systems using immunofluorescence microscopy. These studies have demonstrated that anti-MG-H1 and anti-MG-H3 staining is concentrated within the nucleus, while anti-MG-H2 affords only minimal signal. These observations are consistent with reported formation preferences for MG-Hs, and may suggest novel nuclear targets for non-enzymatic posttranslational modification. The antibody reagents reported herein, as well as the strategy employed for their creation, are likely to prove useful for the immunochemical study of AGEs in biological systems.

  10. Advanced glycation end products (AGEs) promote melanogenesis through receptor for AGEs

    PubMed Central

    Lee, Eun Jung; Kim, Ji Young; Oh, Sang Ho

    2016-01-01

    Accumulation of advanced glycation end products (AGEs) is linked with development or aggravation of many degenerative processes or disorders, including aging and atherosclerosis. AGEs production in skin cells is known to promote stiffness and loss of elasticity through their buildup in connective tissue. However, the impact of AGEs has yet to be fully explored in melanocytes. In this study, we confirmed the existence of receptor for AGE (RAGE) in melanocytes in western blot and immunofluorescence along with increased melanin production in ex vivo skin organ culture and in vitro melanocyte culture following AGEs treatment. Cyclic AMP response element-binding protein (CREB) and extracellular signal-regulated kinases (ERK) 1/2 are considered as key regulatory proteins in AGEs-induced melanogenesis. In addition, blockage experiment using anti-RAGE blocking antibody has indicated that RAGE plays a pivotal role in AGE-mediated melanogenesis. Therefore, it is apparent that AGEs, known markers of aging, promote melanogenesis via RAGE. In addition, AGEs could be implicated in pigmentation associated with photoaging according to the results of increased secretion of AGEs from keratinocytes following UV irradiation. AGE-mediated melanogenesis may thus hold promise as a novel mean of altering skin pigmentation. PMID:27293210

  11. Metformin reverts deleterious effects of advanced glycation end-products (AGEs) on osteoblastic cells.

    PubMed

    Schurman, L; McCarthy, A D; Sedlinsky, C; Gangoiti, M V; Arnol, V; Bruzzone, L; Cortizo, A M

    2008-06-01

    Advanced glycation endproducts (AGEs) are implicated in the complications of diabetes and ageing, affecting several tissues, including bone. Metformin, an insulin-sensitizer drug, reduces the risk of life-threatening macrovascular complications. We have evaluated the hypothesis that metformin can abrogate AGE-induced deleterious effects in osteoblastic cells in culture. In two osteoblast-like cell lines (UMR106 and MC3T3E1), AGE-modified albumin induced cell death, caspase-3 activity, altered intracellular oxidative stress and inhibited alkaline phosphatase activity. Metformin-treatment of osteoblastic cells prevented these AGE-induced alterations. We also assessed the expression of AGE receptors as a possible mechanism by which metformin could modulate the action of AGEs. AGEs-treatment of osteoblast-like cells enhanced RAGE protein expression, and this up-regulation was prevented in the presence of metformin. Although the precise mechanisms involved in metformin signaling are still elusive, our data implicate the AGE-RAGE interaction in the modulation of growth and differentiation of osteoblastic cells.

  12. Two new prenylflavonoids from Epimedii Herba and their inhibitory effects on advanced glycation end-products.

    PubMed

    Nakashima, Keisuke; Miyashita, Hiroyuki; Yoshimitsu, Hitoshi; Fujiwara, Yukio; Nagai, Ryoji; Ikeda, Tsuyoshi

    2016-04-01

    Because inhibitors of advanced glycation end-products (AGEs), for example pyridoxamine, significantly inhibit the development of retinopathy and neuropathy in rats with streptozotocin-induced diabetes, treatment with AGE inhibitors is believed to be a potential strategy for the prevention of lifestyle-related diseases such as diabetic complications. In the present study, the MeOH extract of Epimedii Herba (EH; aerial parts of Epimedium spp.) was found to inhibit the formation of N (ε) -(carboxymethyl)lysine (CML) and N (ω) -(carboxymethyl)arginine (CMA) during incubation of collagen-derived gelatin with ribose. Furthermore, compounds with inhibitory effects against CML and CMA formation were isolated from EH. Two new prenylflavonoids (compounds 1 and 2) and two known compounds (3 and 4) were found to significantly inhibit the formation of both CML and CMA; compound 4 (epimedokoreanin B) had the strongest inhibitory effect of the isolated compounds. These data suggest that epimedokoreanin B could prevent clinical complications of diabetes by inhibiting AGEs.

  13. Advanced glycation end products increase retinal vascular endothelial growth factor expression.

    PubMed Central

    Lu, M; Kuroki, M; Amano, S; Tolentino, M; Keough, K; Kim, I; Bucala, R; Adamis, A P

    1998-01-01

    Advanced glycation end products (AGEs) are linked with the development of diabetic retinopathy; however, the pathogenic mechanisms are poorly defined. Vascular endothelial growth factor (VEGF) levels are increased in ischemic and nonischemic diabetic retina, and VEGF is required for the development of retinal and iris neovascularization. Moreover, VEGF alone can induce much of the concomitant pathology of diabetic retinopathy. In this study, we found that AGEs increased VEGF mRNA levels in the ganglion, inner nuclear, and retinal pigment epithelial (RPE) cell layers of the rat retina. In vitro, AGEs increased VEGF mRNA and secreted protein in human RPE and bovine vascular smooth muscle cells. The AGE-induced increases in VEGF expression were dose- and time-dependent, inhibited by antioxidants, and additive with hypoxia. Use of an anti-VEGF antibody blocked the capillary endothelial cell proliferation induced by the conditioned media of AGE-treated cells. AGEs may participate in the pathogenesis of diabetic retinopathy through their ability to increase retinal VEGF gene expression. PMID:9502762

  14. Assessment of advanced glycated end product accumulation in skin using auto fluorescence multispectral imaging.

    PubMed

    Larsson, Marcus; Favilla, Riccardo; Strömberg, Tomas

    2016-04-12

    Several studies have shown that advanced glycation end products (AGE) play a role in both the microvascular and macrovascular complications of diabetes and are closely linked to inflammation and atherosclerosis. AGEs accumulate in skin and can be detected using their auto fluorescence (AF). A significant correlation exists between AGE AF and the levels of AGEs as obtained from skin biopsies. A commercial device, the AGE Reader, has become available to assess skin AF for clinical purposes but, while displaying promising results, it is limited to single-point measurements performed in contact to skin tissue. Furthermore, in vivo imaging of AGE accumulation is virtually unexplored. We proposed a non-invasive, contact-less novel technique for quantifying fluorescent AGE deposits in skin tissue using a multispectral imaging camera setup (MSI) during ultraviolet (UV) exposure. Imaging involved applying a region-of-interest mask, avoiding specular reflections and a simple calibration. Results of a study conducted on 16 subjects with skin types ranging from fair to deeply pigmented skin, showed that AGE measured with MSI in forearm skin was significantly correlated with the AGE reference method (AGE Reader on forearm skin, R=0.68, p=0.005). AGE measured in facial skin was borderline significantly related to AGE Reader on forearm skin (R=0.47, p=0.078). These results support the use of the technique in devices for non-touch measurement of AGE content in either facial or forearm skin tissue over time.

  15. Advanced glycation end-products: a biological consequence of lifestyle contributing to cancer disparity

    PubMed Central

    Turner, David P.

    2015-01-01

    Low income, poor diet, obesity and a lack of exercise are inter-related lifestyle factors that can profoundly alter our biological make-up to increase cancer risk, growth and development. We recently reported a potential mechanistic link between carbohydrate derived metabolites and cancer which may provide a biological consequence of lifestyle that can directly impact tumor biology. Advanced glycation end-products (AGEs) are reactive metabolites produced as a by-product of sugar metabolism. Failure to remove these highly reactive metabolites can lead to protein damage, aberrant cell signaling, increased stress responses, and decreased genetic fidelity. Critically, AGE accumulation is also directly affected by our lifestyle choices and shows a race specific, tumor dependent pattern of accumulation in cancer patients. This review will discuss the contribution of AGEs to the cancer phenotype with a particular emphasis on their biological links with the socioeconomic and environmental risk factors that drive cancer disparity. Given the potential benefits of lifestyle changes and the potential biological role of AGEs in promoting cancer, opportunities exist for collaborations impacting basic, translational, epidemiological and cancer prevention initiatives. PMID:25920350

  16. Receptor for Advanced Glycation End Products and Its Involvement in Inflammatory Diseases

    PubMed Central

    Talib, Herni; Tie, Tung Hing; Nordin, Norshariza

    2013-01-01

    The receptor for advanced glycation end products (RAGE) is a transmembrane receptor of the immunoglobulin superfamily, capable of binding a broad repertoire of ligands. RAGE-ligands interaction induces a series of signal transduction cascades and lead to the activation of transcription factor NF-κB as well as increased expression of cytokines, chemokines, and adhesion molecules. These effects endow RAGE with the role in the signal transduction from pathogen substrates to cell activation during the onset and perpetuation of inflammation. RAGE signaling and downstream pathways have been implicated in a wide spectrum of inflammatory-related pathologic conditions such as arteriosclerosis, Alzheimer's disease, arthritis, acute respiratory failure, and sepsis. Despite the significant progress in other RAGE studies, the functional importance of the receptor in clinical situations and inflammatory diseases still remains to be fully realized. In this review, we will summarize current understandings and lines of evidence on the molecular mechanisms through which RAGE signaling contributes to the pathogenesis of the aforementioned inflammation-associated conditions. PMID:24102034

  17. Statins stimulate the production of a soluble form of the receptor for advanced glycation end products

    PubMed Central

    Quade-Lyssy, Patricia; Kanarek, Anna Maria; Baiersdörfer, Markus; Postina, Rolf; Kojro, Elzbieta

    2013-01-01

    The beneficial effects of statin therapy in the reduction of cardiovascular pathogenesis, atherosclerosis, and diabetic complications are well known. The receptor for advanced glycation end products (RAGE) plays an important role in the progression of these diseases. In contrast, soluble forms of RAGE act as decoys for RAGE ligands and may prevent the development of RAGE-mediated disorders. Soluble forms of RAGE are either produced by alternative splicing [endogenous secretory RAGE (esRAGE)] or by proteolytic shedding mediated by metalloproteinases [shed RAGE (sRAGE)]. Therefore we analyzed whether statins influence the production of soluble RAGE. Lovastatin treatment of either mouse alveolar epithelial cells endogenously expressing RAGE or HEK cells overexpressing RAGE caused induction of RAGE shedding, but did not influence secretion of esRAGE from HEK cells overexpressing esRAGE. Lovastatin-induced secretion of sRAGE was also evident after restoration of the isoprenylation pathway, demonstrating a correlation of sterol biosynthesis and activation of RAGE shedding. Lovastatin-stimulated induction of RAGE shedding was completely abolished by a metalloproteinase ADAM10 inhibitor. We also demonstrate that statins stimulate RAGE shedding at low physiologically relevant concentrations. Our results show that statins, due to their cholesterol-lowering effects, increase the soluble RAGE level by inducing RAGE shedding, and by doing this, might prevent the development of RAGE-mediated pathogenesis. PMID:23966666

  18. RAGE (Receptor for Advanced Glycation Endproducts), RAGE Ligands, and their role in Cancer and Inflammation

    PubMed Central

    Sparvero, Louis J; Asafu-Adjei, Denise; Kang, Rui; Tang, Daolin; Amin, Neilay; Im, Jaehyun; Rutledge, Ronnye; Lin, Brenda; Amoscato, Andrew A; Zeh, Herbert J; Lotze, Michael T

    2009-01-01

    The Receptor for Advanced Glycation Endproducts [RAGE] is an evolutionarily recent member of the immunoglobulin super-family, encoded in the Class III region of the major histocompatability complex. RAGE is highly expressed only in the lung at readily measurable levels but increases quickly at sites of inflammation, largely on inflammatory and epithelial cells. It is found either as a membrane-bound or soluble protein that is markedly upregulated by stress in epithelial cells, thereby regulating their metabolism and enhancing their central barrier functionality. Activation and upregulation of RAGE by its ligands leads to enhanced survival. Perpetual signaling through RAGE-induced survival pathways in the setting of limited nutrients or oxygenation results in enhanced autophagy, diminished apoptosis, and (with ATP depletion) necrosis. This results in chronic inflammation and in many instances is the setting in which epithelial malignancies arise. RAGE and its isoforms sit in a pivotal role, regulating metabolism, inflammation, and epithelial survival in the setting of stress. Understanding the molecular structure and function of it and its ligands in the setting of inflammation is critically important in understanding the role of this receptor in tumor biology. PMID:19292913

  19. Advanced Glycation End Products are Increased in the Skin and Blood of Patients with Severe Psoriasis.

    PubMed

    Papagrigoraki, Anastasia; Del Giglio, Micol; Cosma, Chiara; Maurelli, Martina; Girolomoni, Giampiero; Lapolla, Annunziata

    2017-03-30

    Psoriasis is frequently associated with metabolic comorbidities. Advanced glycation end products (AGEs) are highly oxidant, biologically active compounds that accumulate in tissues in association with hyperglycaemia, hyperlipidaemia and oxidative stress. This is a cross-sectional case-control study involving 80 patients with mild/severe psoriasis and 80 controls matched for age, sex and body mass index (40 with severe eczema, 40 healthy individuals). Patients and healthy individuals with a smoking habit, diabetes, dyslipidaemia, hypercholesterolaemia, hypertension or who were under systemic treatment were excluded from the study. Skin AGEs were measured in normal-appearing skin by a standard fluorescence technique, and blood AGEs (total AGEs, pentosidine and AGEs receptor) by enzyme-linked immunosorbent assay. Levels of cutaneous AGEs (p < 0.04), serum AGEs (p < 0.03) and pentosidine (p < 0.05) were higher in patients with severe psoriasis. Cutaneous AGEs correlated well with serum AGEs (r = 0.93, p < 0.0001) and with Psoriasis Area and Severity Index score (r = 0.91, p < 0.0001). Receptor levels were lower (p < 0.001) in severe psoriasis, and inversely correlated with disease severity (r = -0.71, p < 0.0002). Patients with severe psoriasis have accumulation of skin and serum AGEs, independent of associated metabolic disorders.

  20. Receptor for advanced glycation end as drug targets in diabetes-induced skin lesion.

    PubMed

    Chen, Xiang-Fang; Tang, Wei; Lin, Wei-Dong; Liu, Zi-Yu; Lu, Xiao-Xiao; Zhang, Bei; Ye, Fei; Liu, Zhi-Min; Zou, Jun-Jie; Liao, Wan-Qing

    2017-01-01

    The involvement of the receptor for advanced glycation end (RAGE) in different diseases has been reviewed in great detail, previously, but the effects of diabetic drugs on RAGE-induced skin lesion during long course diabetes remains poorly understood. In the present study, we have shown that RAGE was overexpressed in both diabetic rats and human keratinocytes (HaCaT cells). Cell cycle arrest and apoptosis as well as alternations of relative protein levels were also found in diabetic rats and HaCaT cells with overexpression of RAGE that were rectified by metformin (Met) treatment. Moreover, overexpression of RAGE was also found to induce secretions of TNF-α, IL-1β, IL-6, ICAM-1 and COX-2 in HaCaT cells, and Met treatment corrected these inflammatory factor secretions. In addition, treatment with Met markedly reduced RAGE overexpression-induced p38 and NF-κB activation. Taken together, the findings of the present study have demonstrated, for the first time that Met protects HaCaT cells against diabetes-induced injuries and inflammatory responses through inhibiting activated RAGE.

  1. The Role of Advanced Glycation End-Products in Cancer Disparity.

    PubMed

    Turner, D P

    2017-01-01

    While the socioeconomic and environmental factors associated with cancer disparity have been well documented, the contribution of biological factors is an emerging field of research. Established disparity factors such as low income, poor diet, drinking alcohol, smoking, and a sedentary lifestyle may have molecular effects on the inherent biological makeup of the tumor itself, possibly altering cell signaling events and gene expression profiles to profoundly alter tumor development and progression. Our understanding of the molecular and biological consequences of poor lifestyle is lacking, but such information may significantly change how we approach goals to reduce cancer incidence and mortality rates within minority populations. In this review, we will summarize the biological, socioeconomic, and environmental associations between a group of reactive metabolites known as advanced glycation end-products (AGEs) and cancer health disparity. Due to their links with lifestyle and the activation of disease-associated pathways, AGEs may represent both a biological consequence and a bio-behavioral indicator of poor lifestyle which may be targeted within specific populations to reduce disparities in cancer incidence and mortality.

  2. The receptor for advanced glycation end products RAGE is involved in corneal healing.

    PubMed

    Nass, Norbert; Trau, Stefanie; Paulsen, Friedrich; Kaiser, Delia; Kalinski, Thomas; Sel, Saadettin

    2017-02-03

    Impaired corneal healing is still a major cause of blindness. As RAGE (receptor for advanced glycation endproducts) is involved in inflammation and wound healing in other tissues, we here investigated its relevance for corneal wound healing. Corneal re-epithelialization after alkaline injury was analysed in an ex-vivo approach with cultured, enucleated eyes from mice either of the C57Bl/6 NChR genotype (RAGE+/+) and mice of the same strain lacking the RAGE gene (RAGE-/-). The wound area was determined time dependently by fluorescence imaging using fluorescein staining. The eyes of RAGE-/- mice showed a significantly slower re-epithelialization than eyes of the RAGE+/- and the RAGE+/+ genotype. In immunohistochemistry, RAGE expression was increased in wounded corneas whereas the abundance of the RAGE ligand HMGB1 was unaffected, but an increase in S100b-like proteins was revealed upon injury. However, neither the addition of the RAGE agonist HMGB1 or an HMGB1 antagonising antibody nor bovine S100b protein to the culture medium of the wounded eyes had an effect on corneal wound closure in ex-vivo. Further gene expression analysis by RT-PCR demonstrated an increase in RAGE expression on the mRNA level, no significant regulation of HMGB1 and a differential regulation of the S100 gene family after alkaline burn of the cornea. In conclusion, RAGE is clearly involved in corneal re-epithelialization most probably mediated by signalling via S100 proteins.

  3. Advanced glycation end products: A link between metabolic and endothelial dysfunction in polycystic ovary syndrome?

    PubMed

    Pertynska-Marczewska, Magdalena; Diamanti-Kandarakis, Evanthia; Zhang, John; Merhi, Zaher

    2015-11-01

    Polycystic ovary syndrome (PCOS), a heterogeneous syndrome of reproductive and metabolic alterations, is associated with increased long-term risk of cardiovascular complications. This phenomenon has been linked to an increase in oxidative stress and inflammatory markers. Advanced glycation end products (AGEs) are pro-inflammatory molecules that trigger a state of intracellular oxidative stress and inflammation after binding to their cell membrane receptors RAGE. The activation of the AGE-RAGE axis has been well known to play a role in atherosclerosis in both men and women. Women with PCOS have systemic chronic inflammatory condition even at the ovarian level as represented by elevated levels of serum/ovarian AGEs and increased expression of the pro-inflammatory RAGE in ovarian tissue. Data also showed the presence of sRAGE in the follicular fluid and its potential protective role against the harmful effect of AGEs on ovarian function. Thus, whether AGE-RAGE axis constitutes a link between metabolic and endothelial dysfunction in women with PCOS is addressed in this review. Additionally, we discuss the role of hormonal changes observed in PCOS and how they are linked with the AGE-RAGE axis in order to better understand the nature of this complex syndrome whose consequences extend well beyond reproduction.

  4. Advanced Glycation End Products: Link between Diet and Ovulatory Dysfunction in PCOS?

    PubMed Central

    Garg, Deepika; Merhi, Zaher

    2015-01-01

    PCOS is the most common cause of anovulation in reproductive-aged women with 70% experiencing ovulatory problems. Advanced glycation end products are highly reactive molecules that are formed by non-enzymatic reactions of sugars with proteins, nucleic acids and lipids. AGEs are also present in a variety of diet where substantial increase in AGEs can result due to thermal processing and modifications of food. Elevation in bodily AGEs, produced endogenously or absorbed exogenously from high-AGE diets, is further exaggerated in women with PCOS and is associated with ovulatory dysfunction. Additionally, increased expression of AGEs as pro-inflammatory receptors in the ovarian tissue has been observed in women with PCOS. In this review, we summarize the role of dietary AGEs as mediators of metabolic and reproductive alterations in PCOS. Once a mechanistic understanding of the relationship between AGEs and anovulation is established, there is a promise that such knowledge will contribute to the subsequent development of targeted pharmacological therapies that will treat anovulation and improve ovarian health in women with PCOS. PMID:26690206

  5. Vascular hypertrophy in experimental diabetes. Role of advanced glycation end products.

    PubMed Central

    Rumble, J R; Cooper, M E; Soulis, T; Cox, A; Wu, L; Youssef, S; Jasik, M; Jerums, G; Gilbert, R E

    1997-01-01

    The accelerated formation of advanced glycation end products (AGEs) and the overexpression of transforming growth factor beta (TGF-beta) have both been implicated in the pathogenesis of diabetic microvascular and macrovascular complications. Previous studies in our laboratory have demonstrated that the vascular changes in diabetes include hypertrophy of the mesenteric vasculature. To examine the role of AGEs in this process, streptozotocin-induced diabetic rats and control animals were randomized to receive aminoguanidine, an inhibitor of AGE formation, or no treatment. Animals were studied at 7 d, 3 wk, and 8 mo after induction of diabetes. When compared with control animals, diabetes was associated with an increase in mesenteric vascular weight and an increase in media wall/lumen area. By Northern analysis, TGF-beta1 gene expression was increased 100-150% (P < 0.01) and alpha1 (IV) collagen gene expression was similarly elevated to 30-110% compared to controls (P < 0.05). AGEs and extracellular matrix were present in abundance in diabetic but not in control vessels. Treatment of diabetic rats with aminoguanidine resulted in significant amelioration of the described pathological changes including overexpression of TGF-beta1 and alpha1 (IV) collagen. These data implicate the formation of AGEs in TGF-beta overexpression and tissue changes which accompany the diabetic state. PMID:9062360

  6. Hepatocyte growth factor protects human endothelial cells against advanced glycation end products-induced apoposis

    SciTech Connect

    Zhou Yijun . E-mail: zhou-yijun@hotmail.com; Wang Jiahe; Zhang Jin

    2006-06-02

    Advanced glycation end products (AGEs) form by a non-enzymatic reaction between reducing sugars and biological proteins, which play an important role in the pathogenesis of atherosclerosis. In this study, we assessed AGEs effects on human umbilical vein endothelial cells (HUVECs) growth, proliferation and apoptosis. Additionally, we investigated whether hepatocyte growth factor (HGF), an anti-apoptotic factor for endothelial cells, prevents AGEs-induced apoptosis of HUVECs. HUVECs were treated with AGEs in the presence or absence of HGF. Treatment of HUVECs with AGEs changed cell morphology, decreased cell viability, and induced DNA fragmentation, leading to apoptosis. Apoptosis was induced by AGEs in a dose- and time-dependent fashion. AGEs markedly elevated Bax and decreased NF-{kappa}B, but not Bcl-2 expression. Additionally, AGEs significantly inhibited cell growth through a pro-apoptotic action involving caspase-3 and -9 activations in HUVECs. Most importantly, pretreatment with HGF protected against AGEs-induced cytotoxicity in the endothelial cells. HGF significantly promoted the expression of Bcl-2 and NF-{kappa}B, while decreasing the activities of caspase-3 and -9 without affecting Bax level. Our data suggest that AGEs induce apoptosis in endothelial cells. HGF effectively attenuate AGEs-induced endothelial cell apoptosis. These findings provide new perspectives in the role of HGF in cardiovascular disease.

  7. Receptor for advanced glycation end as drug targets in diabetes-induced skin lesion

    PubMed Central

    Chen, Xiang-Fang; Tang, Wei; Lin, Wei-Dong; Liu, Zi-Yu; Lu, Xiao-Xiao; Zhang, Bei; Ye, Fei; Liu, Zhi-Min; Zou, Jun-Jie; Liao, Wan-Qing

    2017-01-01

    The involvement of the receptor for advanced glycation end (RAGE) in different diseases has been reviewed in great detail, previously, but the effects of diabetic drugs on RAGE-induced skin lesion during long course diabetes remains poorly understood. In the present study, we have shown that RAGE was overexpressed in both diabetic rats and human keratinocytes (HaCaT cells). Cell cycle arrest and apoptosis as well as alternations of relative protein levels were also found in diabetic rats and HaCaT cells with overexpression of RAGE that were rectified by metformin (Met) treatment. Moreover, overexpression of RAGE was also found to induce secretions of TNF-α, IL-1β, IL-6, ICAM-1 and COX-2 in HaCaT cells, and Met treatment corrected these inflammatory factor secretions. In addition, treatment with Met markedly reduced RAGE overexpression-induced p38 and NF-κB activation. Taken together, the findings of the present study have demonstrated, for the first time that Met protects HaCaT cells against diabetes-induced injuries and inflammatory responses through inhibiting activated RAGE. PMID:28337263

  8. Advanced Glycation End Products (AGE) and Diabetes: Cause, Effect, or Both?

    PubMed Central

    Vlassara, Helen; Uribarri, Jaime

    2014-01-01

    Despite new and effective drug therapies, insulin resistance (IR), type 2 diabetes mellitus (T2D) and its complications remain major medical challenges. It is accepted that IR, often associated with over-nutrition and obesity, results from chronically elevated oxidant stress (OS) and chronic inflammation. Less acknowledged is that a major cause for this inflammation is excessive consumption of advanced glycation end products (AGEs) with the standard western diet. AGEs, which were largely thought as oxidative derivatives resulting from diabetic hyperglycemia, are increasingly seen as a potential risk for islet β-cell injury, peripheral IR and diabetes. Here we discuss the relationships between exogenous AGEs, chronic inflammation, IR, and T2D. We propose that under chronic exogenous oxidant AGE pressure the depletion of innate defense mechanisms is an important factor, which raises susceptibility to inflammation, IR, T2D and its complications. Finally we review evidence on dietary AGE restriction as a non-pharmacologic intervention, which effectively lowers AGEs, restores innate defenses and improves IR, thus, offering new perspectives on diabetes etiology and therapy. PMID:24292971

  9. Pentosidine, an Advanced Glycation End-Product, May Reflect Clinical and Morphological Features of Hand Osteoarthritis

    PubMed Central

    Braun, Martin; Hulejová, Hana; Gatterová, Jindřiška; Filková, Mária; Pavelková, Andrea; Šléglová, Olga; Kaspříková, Nikola; Vencovský, Jiří; Pavelka, Karel; Šenolt, Ladislav

    2012-01-01

    The study investigates pentosidine levels, an advanced glycation end-product, in patients with erosive and non-erosive hand osteoarthritis (HOA) and determine its potential association with clinical findings and imaging-defined joint damage. Pentosidine was measured by HPLC in serum and urine of 53 females with HOA (31 erosive and 22 non-erosive HOA) and normalised to the total serum protein or urinary creatinine, respectively. Pain, joint stiffness and disability were assessed by the Australian/Canadian OA hand index (AUSCAN). The hand radiographs scored according to the Kallman grading scale were assessed to determine a baseline value and reassessed after two years. The levels of urine pentosidine, but not of serum pentosidine, were higher in patients with erosive HOA than in non-erosive HOA (p=0.039). Urinary pentosidine correlated with CRP (r=0.302, p=0.031), ESR (r=0.288, p=0.041) and AUSCAN (r=0.408, p=0.003). Serum pentosidine, but not in urine, significantly correlated with the Kallman radiographic score in erosive HOA at the baseline (r=0.409, p=0.022) and after 2 years (r=0.385, p=0.032). However, when corrected for age and disease duration, only correlation between urine pentosidine and AUSCAN remained significant (r=0.397, p=0.004). Our data suggest that serum and urine pentosidine levels may relate to the distinctive clinical and morphological features of HOA. PMID:22715350

  10. Advanced glycation endproducts in 35 types of seafood products consumed in eastern China

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Li, Zhenxing; Pavase, Ramesh Tushar; Lin, Hong; Zou, Long; Wen, Jie; Lv, Liangtao

    2016-08-01

    Advanced glycation endproducts (AGEs) have been recognized as hazards in processed foods that can induce chronic diseases such as cardiovascular disease, diabetes, and diabetic nephropathy. In this study, we investigated the AGEs contents of 35 types of industrial seafood products that are consumed frequently in eastern China. Total fluorescent AGEs level and Nɛ-carboxymethyl-lysine (CML) content were evaluated by fluorescence spectrophotometry and gas chromatography-mass spectrometry (GC-MS), respectively. The level of total fluorescent AGEs in seafood samples ranged from 39.37 to 1178.3 AU, and was higher in canned and packaged instant aquatic products that were processed at high temperatures. The CML content in seafood samples ranged from 44.8 to 439.1 mg per kg dried sample, and was higher in roasted seafood samples. The total fluorescent AGEs and CML content increased when seafood underwent high-temperature processing, but did not show an obvious correlation. The present study suggested that commonly consumed seafood contains different levels of AGEs, and the seafood processed at high temperatures always displays a high level of either AGEs or CML.

  11. Collagen modifications in postmenopausal osteoporosis: advanced glycation endproducts may affect bone volume, structure and quality.

    PubMed

    Willett, Thomas L; Pasquale, Julia; Grynpas, Marc D

    2014-09-01

    The classic model of postmenopausal osteoporosis (PM-OP) starts with the depletion of estrogen, which in turn stimulates imbalanced bone remodeling, resulting in loss of bone mass/volume. Clinically, this leads to fractures because of structural weakness. Recent work has begun to provide a more complete picture of the mechanisms of PM-OP involving oxidative stress and collagen modifications known as advanced glycation endproducts (AGEs). On one hand, AGEs may drive imbalanced bone remodeling through signaling mediated by the receptor for AGEs (RAGE), stimulating resorption and inhibiting formation. On the other hand, AGEs are associated with degraded bone material quality. Oxidative stress promotes the formation of AGEs, inhibits normal enzymatically derived crosslinking and can degrade collagen structure, thereby reducing fracture resistance. Notably, there are multiple positive feedback loops that can exacerbate the mechanisms of PM-OP associated with oxidative stress and AGEs. Anti-oxidant therapies may have the potential to inhibit the oxidative stress based mechanisms of this disease.

  12. Hydrogen Sulfide Prevents Advanced Glycation End-Products Induced Activation of the Epithelial Sodium Channel

    PubMed Central

    Wang, Qiushi; Song, Binlin; Jiang, Shuai; Liang, Chen; Chen, Xiao; Shi, Jing; Li, Xinyuan; Sun, Yingying; Wu, Mingming; Zhao, Dan; Zhang, Zhi-Ren; Ma, He-Ping

    2015-01-01

    Advanced glycation end-products (AGEs) are complex and heterogeneous compounds implicated in diabetes. Sodium reabsorption through the epithelial sodium channel (ENaC) at the distal nephron plays an important role in diabetic hypertension. Here, we report that H2S antagonizes AGEs-induced ENaC activation in A6 cells. ENaC open probability (PO) in A6 cells was significantly increased by exogenous AGEs and that this AGEs-induced ENaC activity was abolished by NaHS (a donor of H2S) and TEMPOL. Incubating A6 cells with the catalase inhibitor 3-aminotriazole (3-AT) mimicked the effects of AGEs on ENaC activity, but did not induce any additive effect. We found that the expression levels of catalase were significantly reduced by AGEs and both AGEs and 3-AT facilitated ROS uptake in A6 cells, which were significantly inhibited by NaHS. The specific PTEN and PI3K inhibitors, BPV(pic) and LY294002, influence ENaC activity in AGEs-pretreated A6 cells. Moreover, after removal of AGEs from AGEs-pretreated A6 cells for 72 hours, ENaC PO remained at a high level, suggesting that an AGEs-related “metabolic memory” may be involved in sodium homeostasis. Our data, for the first time, show that H2S prevents AGEs-induced ENaC activation by targeting the ROS/PI3K/PTEN pathway. PMID:26078825

  13. Hydrogen Sulfide Prevents Advanced Glycation End-Products Induced Activation of the Epithelial Sodium Channel.

    PubMed

    Wang, Qiushi; Song, Binlin; Jiang, Shuai; Liang, Chen; Chen, Xiao; Shi, Jing; Li, Xinyuan; Sun, Yingying; Wu, Mingming; Zhao, Dan; Zhang, Zhi-Ren; Ma, He-Ping

    2015-01-01

    Advanced glycation end-products (AGEs) are complex and heterogeneous compounds implicated in diabetes. Sodium reabsorption through the epithelial sodium channel (ENaC) at the distal nephron plays an important role in diabetic hypertension. Here, we report that H2S antagonizes AGEs-induced ENaC activation in A6 cells. ENaC open probability (P O ) in A6 cells was significantly increased by exogenous AGEs and that this AGEs-induced ENaC activity was abolished by NaHS (a donor of H2S) and TEMPOL. Incubating A6 cells with the catalase inhibitor 3-aminotriazole (3-AT) mimicked the effects of AGEs on ENaC activity, but did not induce any additive effect. We found that the expression levels of catalase were significantly reduced by AGEs and both AGEs and 3-AT facilitated ROS uptake in A6 cells, which were significantly inhibited by NaHS. The specific PTEN and PI3K inhibitors, BPV(pic) and LY294002, influence ENaC activity in AGEs-pretreated A6 cells. Moreover, after removal of AGEs from AGEs-pretreated A6 cells for 72 hours, ENaC P O remained at a high level, suggesting that an AGEs-related "metabolic memory" may be involved in sodium homeostasis. Our data, for the first time, show that H2S prevents AGEs-induced ENaC activation by targeting the ROS/PI3K/PTEN pathway.

  14. Protection effect of endomorphins on advanced glycation end products induced injury in endothelial cells.

    PubMed

    Liu, Jing; Yan, Liping; Niu, Ruilan; Tian, Limin; Zhang, Qi; Quan, Jinxing; Liu, Hua; Wei, Suhong; Guo, Qian

    2013-01-01

    Endomorphins (EMs) have a very important bridge-function in cardiovascular, endocrinological, and neurological systems. This study is to investigate the effects of EMs on the synthesis and secretion of vasoactive substances induced by advanced glycation end products in primary cultured human umbilical vein endothelial cells (HUVECs). Firstly, HUVECs were stimulated with AGEs-bovine serum albumin (AGEs-BSA), bovine serum albumin (BSA), or both AGEs-BSA and EMs together, respectively. Then, HUVEC survival rate was calculated by MTT assay, the levels of NO, endothelial nitric oxide synthase (eNOS), and inducible nitric oxide synthase (iNOS) were detected by colorimetric analysis, and the contents of endothelin-1 (ET-1) were detected by ELISA. The mRNA levels of eNOS and ET-1 were measured by RT-PCR. The expression of p38 mitogen-activated protein kinase (p38 MAPK) was detected by immunofluorescence assay. The results showed that the mRNA expression and secretion of eNOS were significantly enhanced after incubation with EMs compared to those with AGEs-BSA, while the secretion of NO and iNOS, mRNA expression, and secretion of ET-1 had opposite changes. The fluorescence intensity of p38MAPK in nuclear was decreased after pretreatment with EMs compared to incubation with AGEs-BSA. Conclusion. The present study suggests that EMs have certain protection effect on AGEs-BSA-induced injury in HUVEC.

  15. Effects of chebulic acid on advanced glycation endproducts-induced collagen cross-links.

    PubMed

    Lee, Ji-Young; Oh, Jun-Gu; Kim, Jin Sook; Lee, Kwang-Won

    2014-01-01

    Advanced glycation end-products (AGEs) have been implicated in the development of diabetic complications. We report the antiglycating activity of chebulic acid (CA), isolated from Terminalia chebula on breaking the cross-links of proteins induced by AGEs and inhibiting the formation of AGEs. Aminoguanidine (AG) reduced 50% of glycated bovine serum albumin (BSA) with glycolaldehyde (glycol-BSA)-induced cross-links of collagen at a concentration of 67.8 ± 2.5 mM, the level of CA required for exerting a similar antiglycating activity was 38.8 ± 0.5 µM. Also, the breaking activity on collagen cross-links induced by glycol-BSA was potent with CA (IC50=1.46 ± 0.05 mM), exhibiting 50-fold stronger breaking activity than with ALT-711, a well-known cross-link breaker (IC50=72.2 ± 2.4 mM). IC50 values of DPPH· scavenging activity for CA and ascorbic acid (AA) were 39.2 ± 4.9 and 19.0 ± 1.2 µg dry matter (DM) mL(-1), respectively, and ferric reducing and antioxidant power (FRAP) activities for CA and AA were 4.70 ± 0.06 and 11.4 ± 0.1 mmol/FeSO4·7H2O/g DM, respectively. The chelating activities of CA, AG and ALT711 on copper-catalyzed oxidation of AA were compared, and in increasing order, ALT-711 (IC50 of 1.92 ± 0.20 mM)

  16. Pathological Significance of Mitochondrial Glycation

    PubMed Central

    Pun, Pamela Boon Li; Murphy, Michael P.

    2012-01-01

    Glycation, the nonenzymatic glycosylation of biomolecules, is commonly observed in diabetes and ageing. Reactive dicarbonyl species such as methylglyoxal and glyoxal are thought to be major physiological precursors of glycation. Because these dicarbonyls tend to be formed intracellularly, the levels of advanced glycation end products on cellular proteins are higher than on extracellular ones. The formation of glycation adducts within cells can have severe functional consequences such as inhibition of protein activity and promotion of DNA mutations. Although several lines of evidence suggest that there are specific mitochondrial targets of glycation, and mitochondrial dysfunction itself has been implicated in disease and ageing, it is unclear if glycation of biomolecules specifically within mitochondria induces dysfunction and contributes to disease pathology. We discuss here the possibility that mitochondrial glycation contributes to disease, focussing on diabetes, ageing, cancer, and neurodegeneration, and highlight the current limitations in our understanding of the pathological significance of mitochondrial glycation. PMID:22778743

  17. Chemo-enzymatic synthesis of vinyl and l-ascorbyl phenolates and their inhibitory effects on advanced glycation end products.

    PubMed

    Hwang, Seung Hwan; Wang, Zhiqiang; Lim, Soon Sung

    2017-01-01

    This study successfully established the feasibility of a two-step chemo-enzymatic synthesis of l-ascorbyl phenolates. Intermediate vinyl phenolates were first chemically produced and then underwent trans-esterification with l-ascorbic acid in the presence of Novozyme 435® (Candida Antarctica lipase B) as a catalyst. Twenty vinyl phenolates and 11 ascorbyl phenolates were subjected to in vitro bioassays to investigate their inhibitory activity against advanced glycation end products (AGEs). Among them, vinyl 4-hydroxycinnamate (17VP), vinyl 4-hydroxy-3-methoxycinnamate (18VP), vinyl 4-hydroxy-3,5-dimethoxycinnamate (20VP), ascorbyl 4-hydroxy-3-methoxycinnamate (18AP) and ascorbyl 3,4-dimethoxycinnamate (19AP) showed 2-10 times stronger inhibitory activities than positive control (aminoguanidine and its precursors). These results indicated that chemo-enzymatically synthesized compounds have AGE inhibitory effect and thus are effective in either preventing or retarding glycation protein formation.

  18. [Advanced glycation and lipoxidation end products--amplifiers of inflammation: the role of food].

    PubMed

    Gil, A; Bengmark, S

    2007-01-01

    Chronic diseases (CD) represent the main cause of mortality in developed countries. The increase in the prevalence of of CD is associated with changes in lifestyle habits, including those related to the consumption of processed foodstuffs. In these foods advanced glycation end products (AGE) and advanced lipoperoxydation products (ALE) are formed as a consequence of the reactivity of proteins, carbohydrates, lipid and other components. The aim of the present review is to offer a perspective of how AGE and ALE affect the physiology and development of CD. Continous intake of AGE and ALE contributes to the exccesive accumulation of these products into body tissues, which in turn negatively influence the innate immune system, inflammatory responses, and resistance to diseases. This is achieved by direct interaction of AGE and ALE with specific cell AGE receptors (RAGE) that have a key role as master switches regulating the development of CD. Long-life molecules, namely collagen and myelin, and low-turnover tissues, e.g. connective, bone and neural tissues, are the main targets of AGE and ALE. In these tissues, AGE and ALE lead to the synthesis of insoluble compounds that severely alter cellular functionality. It has been reported associations of AGE and ALE with allergic and autoimmune diseases, Alzheimer disease and other degenerative disorders, catarats, atherosclerosis, cancer, and diabetes mellitus type 2, as well as a number of endocrine, gastrointestinal, skeleton-muscle, and urogenital alterations. Controlling all those pathologies would need further dietary recommendations aiming to limit the intake of processed foods rich in AGE and ALE, as well as to reduce the formation of those products by improving technological processes applicable to foods.

  19. Clinical Value of High Mobility Group Box 1 and the Receptor for Advanced Glycation End-products in Head and Neck Cancer: A Systematic Review.

    PubMed

    Nguyen, Austin; Bhavsar, Sheila; Riley, Erinn; Caponetti, Gabriel; Agrawal, Devendra

    2016-10-01

    Introduction High mobility group box 1 is a versatile protein involved in gene transcription, extracellular signaling, and response to inflammation. Extracellularly, high mobility group box 1 binds to several receptors, notably the receptor for advanced glycation end-products. Expression of high mobility group box 1 and the receptor for advanced glycation end-products has been described in many cancers. Objectives To systematically review the available literature using PubMed and Web of Science to evaluate the clinical value of high mobility group box 1 and the receptor for advanced glycation end-products in head and neck squamous cell carcinomas. Data synthesis A total of eleven studies were included in this review. High mobility group box 1 overexpression is associated with poor prognosis and many clinical and pathological characteristics of head and neck squamous cell carcinomas patients. Additionally, the receptor for advanced glycation end-products demonstrates potential value as a clinical indicator of tumor angiogenesis and advanced staging. In diagnosis, high mobility group box 1 demonstrates low sensitivity. Conclusion High mobility group box 1 and the receptor for advanced glycation end-products are associated with clinical and pathological characteristics of head and neck squamous cell carcinomas. Further investigation of the prognostic and diagnostic value of these molecules is warranted.

  20. Inhibition of fluorescent advanced glycation end products (AGEs) of human serum albumin upon incubation with 3-β-hydroxybutyrate.

    PubMed

    Bohlooli, M; Moosavi-Movahedi, A A; Taghavi, F; Saboury, A A; Maghami, P; Seyedarabi, A; Moosavi-Movahedi, F; Ahmad, F; Shockravi, A; Habibi-Rezaei, M

    2014-06-01

    Advanced glycation end products (AGEs), which are the final products of glycation, have a major role in diabetic complication and neurodegenerative disorders. The 3-β-hydroxybutyrate (3BHB), a ketone body which is produced by the liver, can be detected in increased concentrations in individuals post fasting and prolonged exercises and in diabetic (type I) patients. In this study, the inhibitory effect of 3BHB on AGEs formation by glucose from the human serum albumin (HSA) was studied at physiological conditions after 35 days of incubation, using physical techniques such as circular dichroism and fluorescence spectroscopy, as well as differential scanning calorimetry (DSC). The fluorescence intensity measurements of glycated HSA by glucose (GHSA) in the presence of 3BHB indicate a decrease in AGEs formation. The DSC deconvolution profile results also confirm the protective role of 3BHB on incubated with glucose by preventing the enthalpy reduction of the HSA tail segment, compared with the deconvolution profile seen for incubated with glucose alone. The concentration of 3BHB used in this study is in accordance with the concentration detected in the body of individuals post fasting and prolonged exercises.

  1. Phlorotannins from brown algae (Fucus vesiculosus) inhibited the formation of advanced glycation endproducts by scavenging reactive carbonyls.

    PubMed

    Liu, Haiyan; Gu, Liwei

    2012-02-08

    Accumulation of advanced glycation end products (AGEs) in vivo is associated with aging, diabetes, Alzheimer's disease, renal failure, etc. The objective of this study was to investigate the inhibitory effects of brown algae Fucus vesiculosus phlorotannins on the formation of AGEs. F. vesiculosus phlorotannins were extracted using 70% acetone. The resultant extract was fractionated into dichloromethane, ethyl acetate, butanol, and water fractions. The ethyl acetate fraction was further fractionated into four subfractions (Ethyl-F1 to -F4) using a Sephadex LH-20 column. F. vesiculosus acetone extract or fractions significantly inhibited the formation of AGEs mediated by glucose and methylglyoxal in a concentration-dependent manner. The concentrations of F. vesiculosus extracts required to inhibit 50% of albumin glycation (EC(50)) in the bovine serum albumin (BSA)-methylglyoxal assay were lower than those of aminoguanidine (a drug candidate for diabetic complication), except for F. vesiculosus acetone extract and dichloromethane fraction. In the BSA-glucose assay, F. vesiculosus extracts inhibited BSA glycation more than or as effectively as aminoguanidine, except for Ethyl-F3 and -F4. The ethyl acetate fraction and its four subfractions scavenged more than 50% of methylglyoxal in two hours. The hypothesis whether F. vesiculosus phlorotannins scavenged reactive carbonyls by forming adducts was tested. Phloroglucinol, the constituent unit of phlorotannins, reacted with glyoxal and methylglyoxal. Five phloroglucinol-carbonyl adducts were detected and tentatively identified using HPLC-ESI-MS(n).

  2. Methylglyoxal, advanced glycation end products and autism: is there a connection?

    PubMed

    Maher, P

    2012-04-01

    Autism is a complex and heterogeneous neurodevelopmental disorder of unknown etiology but very likely resulting from both genetic and environmental factors. Recent estimates suggest that it affects 1 in 100-150 individuals in the US. Oxidative stress, inflammation and mitochondrial dysfunction have all been suggested to play key roles in autism and may be linked via alterations in cellular redox homeostasis. The glutathione/glutathione disulfide (GSH/GSSG) redox pair forms the major redox couple in cells and as such plays a critical role in regulating redox-dependent cellular functions. A number of studies have shown that variations in genes involved in GSH metabolism are associated with autism. GSH also modulates the activity of glyoxalase 1 (Glo-1), the rate-limiting enzyme for the removal of reactive dicarbonyls such as methylglyoxal (MG). MG is the major precursor for the formation of advanced glycation end products (AGEs). Both MG and AGEs can induce oxidative stress, inflammation and mitochondrial dysfunction and are implicated in diabetic complications and multiple, age-related neurological diseases. Dietary consumption of AGEs and MG correlates with food intake which has increased 20-30% over the past 20 years. Both MG and AGEs are orally absorbed, leading to increased levels in the blood. Furthermore, in humans, increased MG and AGE levels in maternal blood correlate with increased MG and AGE levels in newborn blood, potentially exposing infants to high oxidative stress and inflammation. It is hypothesized that diet derived MG and AGEs in combination with inborn genetic vulnerabilities that affect the cellular redox status are major contributors to the development of autism and provide a causal link between oxidative stress, inflammation and mitochondrial dysfunction. If future research supports this hypothesis, then by reducing the exposure to these diet-derived factors, it might be possible to decrease the prevalence of at least a subset of autism cases.

  3. Blockade of advanced glycation end-product formation restores ischemia-induced angiogenesis in diabetic mice

    PubMed Central

    Tamarat, Radia; Silvestre, Jean-Sébastien; Huijberts, Maya; Benessiano, Joelle; Ebrahimian, Teni G.; Duriez, Micheline; Wautier, Marie-Paule; Wautier, Jean Luc; Lévy, Bernard I.

    2003-01-01

    We hypothesized that formation of advanced glycation end products (AGEs) associated with diabetes reduces matrix degradation by metalloproteinases (MMPs) and contributes to the impairment of ischemia-induced angiogenesis. Mice were treated or not with streptozotocin (40 mg/kg) and streptozotocin plus aminoguanidine (AGEs formation blocker, 50 mg/kg). After 8 weeks of treatment, hindlimb ischemia was induced by right femoral artery ligature. Plasma AGE levels were strongly elevated in diabetic mice when compared with control mice (579 ± 21 versus 47 ± 4 pmol/ml, respectively; P < 0.01). Treatment with aminoguanidine reduced AGE plasma levels when compared with untreated diabetic mice (P < 0.001). After 28 days of ischemia, ischemic/nonischemic leg angiographic score, capillary density, and laser Doppler skin-perfusion ratios were 1.4-, 1.5-, and 1.4-fold decreased in diabetic mice in reference to controls (P < 0.01). Treatment with aminoguanidine completely normalized ischemia-induced angiogenesis in diabetic mice. We next analyzed the role of proteolysis in AGE formation-induced hampered neovascularization process. After 3 days of ischemia, MMP-2 activity and MMP-3 and MMP-13 protein levels were increased in untreated and aminoguanidine-treated diabetic mice when compared with controls (P < 0.05). Despite this activation of the MMP pathway, collagenolysis was decreased in untreated diabetic mice. Conversely, treatment of diabetic mice with aminoguanidine restored collagenolysis toward levels found in control mice. In conclusion, blockade of AGE formation by aminoguanidine normalizes impaired ischemia-induced angiogenesis in diabetic mice. This effect is probably mediated by restoration of matrix degradation processes that are disturbed as a result of AGE accumulation. PMID:12805564

  4. Blockade of advanced glycation end-product formation restores ischemia-induced angiogenesis in diabetic mice.

    PubMed

    Tamarat, Radia; Silvestre, Jean-Sébastien; Huijberts, Maya; Benessiano, Joelle; Ebrahimian, Teni G; Duriez, Micheline; Wautier, Marie-Paule; Wautier, Jean Luc; Lévy, Bernard I

    2003-07-08

    We hypothesized that formation of advanced glycation end products (AGEs) associated with diabetes reduces matrix degradation by metalloproteinases (MMPs) and contributes to the impairment of ischemia-induced angiogenesis. Mice were treated or not with streptozotocin (40 mg/kg) and streptozotocin plus aminoguanidine (AGEs formation blocker, 50 mg/kg). After 8 weeks of treatment, hindlimb ischemia was induced by right femoral artery ligature. Plasma AGE levels were strongly elevated in diabetic mice when compared with control mice (579 +/- 21 versus 47 +/- 4 pmol/ml, respectively; P < 0.01). Treatment with aminoguanidine reduced AGE plasma levels when compared with untreated diabetic mice (P < 0.001). After 28 days of ischemia, ischemic/nonischemic leg angiographic score, capillary density, and laser Doppler skin-perfusion ratios were 1.4-, 1.5-, and 1.4-fold decreased in diabetic mice in reference to controls (P < 0.01). Treatment with aminoguanidine completely normalized ischemia-induced angiogenesis in diabetic mice. We next analyzed the role of proteolysis in AGE formation-induced hampered neovascularization process. After 3 days of ischemia, MMP-2 activity and MMP-3 and MMP-13 protein levels were increased in untreated and aminoguanidine-treated diabetic mice when compared with controls (P < 0.05). Despite this activation of the MMP pathway, collagenolysis was decreased in untreated diabetic mice. Conversely, treatment of diabetic mice with aminoguanidine restored collagenolysis toward levels found in control mice. In conclusion, blockade of AGE formation by aminoguanidine normalizes impaired ischemia-induced angiogenesis in diabetic mice. This effect is probably mediated by restoration of matrix degradation processes that are disturbed as a result of AGE accumulation.

  5. Contribution of dietary advanced glycation end products (AGE) to circulating AGE: role of dietary fat.

    PubMed

    Davis, Kathleen E; Prasad, Chandan; Vijayagopal, Parakat; Juma, Shanil; Adams-Huet, Beverley; Imrhan, Victorine

    2015-12-14

    The purpose of this pilot study was to determine whether macronutrient content (low-fat v. high-fat diet) influences an indicator of advanced glycation end products (AGE), N(ε) carboxymethyl-lysine (CML), in the context of a 1-d, high-AGE diet. The effect of the diets on inflammatory markers was also assessed. A total of nineteen overweight and obese adults (nine men and ten women) without known disease were recruited to participate in a crossover challenge of a high-fat, high-AGE (HFHA) and low-fat, high-AGE (LFHA) diet. In each phase patients had fasting blood drawn, followed by consumption of a high-fat or low-fat breakfast test meal, then three postprandial blood draws at 1, 2 and 3 h after consuming the test meal. After consuming high-AGE meals for the remainder of the day, participants returned the next day for a follow-up analysis. A different pattern in the 3-h post-meal CML and soluble receptor for AGE response to the two diets was observed (P=0·01 and 0·05, respectively). No change in serum CML was observed following consumption of a LFHA breakfast (535 (25th-75th percentile 451-790) to 495 (25th-75th percentile 391-682) ng/ml; P=0·36), whereas a rise in CML occurred after the HFHA breakfast (463 (25th-75th percentile 428-664) to 578 (25th-75th percentile 474-865) ng/ml; P=0·05). High sensitivity C-reactive protein and high molecular weight adiponectin were not affected by either diet. These findings suggest that dietary CML may not be as important in influencing serum CML as other dietary factors. In addition, acute exposure to dietary CML may not influence inflammation in adults without diabetes or kidney disease. This is contrary to previous findings.

  6. A receptor-based bioadsorbent to target advanced glycation end products in chronic kidney disease.

    PubMed

    Zhang, Yangrong; Lapidos, Karen A; Gal-Moscovici, Anca; Sprague, Stuart M; Ameer, Guillermo A

    2014-06-01

    The accumulation of advanced glycation end products (AGEs) has been reported to be a major contributor to chronic systemic inflammation. AGEs are not efficiently removed by hemodialysis or the kidney of a chronic kidney disease (CKD) patient. The goal of this study was to develop a receptor for AGEs (RAGE)-based bioadsorbent device that was capable of removing endogenous AGEs from human blood. The extracellular domain of RAGE was immobilized onto agarose beads to generate the bioadsorbent. The efficacy of AGE removal from saline, serum, and whole blood; biological effects of AGE reduction; and hemocompatibility and stability of the bioadsorbent were investigated. The bioadsorbent bound AGE-modified bovine serum albumin (AGE-BSA) with a binding capacity of 0.73 ± 0.07 mg AGE-BSA/mL bioadsorbent. The bioadsorbent significantly reduced the concentration of total AGEs in serum isolated from end-stage kidney disease patients by 57%. AGE removal resulted in a significant reduction of vascular cell adhesion molecule-1 expression in human endothelial cells and abolishment of osteoclast formation in osteoclast progenitor cells. A hollow fiber device loaded with bioadsorbent-reduced endogenous AGEs from recirculated blood to 36% of baseline levels with no significant changes in total protein or albumin concentration. The bioadsorbent maintained AGE-specific binding capacity after freeze-drying and storage for 1 year. This approach provides the foundation for further development of soluble RAGE-based extracorporeal therapies to selectively deplete serum AGEs from human blood and decrease inflammation in patients with diabetes and/or CKD.

  7. Advanced glycation end products (AGEs) and its receptors in the pathogenesis of hyperthyroidism.

    PubMed

    Caspar-Bell, Gudrun; Dhar, Indu; Prasad, Kailash

    2016-03-01

    Oxidative stress has been implicated in the pathogenesis of hyperthyroidism and its complications. Interaction of advanced glycation end products (AGEs) with receptor RAGE (receptor for AGEs) generates reactive oxygen species. Soluble receptor for AGEs (sRAGE) competes with RAGE for binding with AGEs and attenuates the generation of ROS. Low levels sRAGE and high levels AGEs would generate more ROS leading to hyperthyroidism and its complications. The objectives are to determine if levels of serum sRAGE are low and the levels of AGEs and AGEs/sRAGE are high in patients with hyperthyroidism. The study subjects comprised of 33 patients with hyperthyroidism and 20 controls. Levels of serum sRAGE were lower, while that of AGEs and AGEs/sRAGE were higher in patients compared to controls, being significant only for sRAGE and AGEs/sRAGE. When the levels of sRAGE, AGEs, and AGEs/sRAGE were assessed for hyperthyroidism associated with different diseases, the levels of sRAGE were lower in Hashimoto disease, and levels of AGEs were higher in patients with Graves' disease compared to control. The levels of AGEs/sRAGE were elevated in an all except patients with Hashimoto disease. The levels of AGEs, sRAGE, or AGEs/RAGE were not correlated with age, weight, and blood pressures except systolic pressure which was inversely correlated with sRAGE. The levels of sRAGE were negatively correlated with AGEs and AGEs/sRAGE. The levels of AGEs/sRAGE were positively correlated with AGEs. In conclusion, low levels of sRAGE, and high levels of AGEs and AGEs/sRAGE are risk biomarkers in the pathogenesis hyperthyroidism and its complications.

  8. Accumulation of advanced glycation end products, measured as skin autofluorescence, in renal disease.

    PubMed

    Hartog, Jasper W L; de Vries, Aiko P J; Lutgers, Helen L; Meerwaldt, Robbert; Huisman, Roel M; van Son, Willem J; de Jong, Paul E; Smit, Andries J

    2005-06-01

    Advanced glycation end products (AGEs) accumulate during renal failure and dialysis. Kidney transplantation is thought to reverse this accumulation by restoring renal function. Using a noninvasive and validated autofluorescence reader, we evaluated AGE levels in 285 transplant recipients (mean age, 52 years; range, 41 to 60 years), 32 dialysis patients (mean age, 56 years; range, 43 to 65 years), and 231 normal control subjects (mean age, 51 years; range, 40 to 65 years). Measurements in transplant recipients were performed for a mean of 73 months (range, 32 to 143 months) after transplantation. Dialysis patients were on dialysis therapy for a mean of 42 months (range, 17 to 107 months). Fluorescence was significantly increased in dialysis patients compared with normal control subjects (2.8 vs. 2.0 arbitrary units [a.u.], P < .0001). Although fluorescence levels were significantly decreased in transplant recipients compared with dialysis patients (2.5 vs. 2.8 a.u., P < .0001), fluorescence in transplant recipients was higher than in controls (2.5 vs. 2.0 a.u., P < .0001). In transplant recipients, fluorescence correlated positively with the duration of dialysis prior to transplantation (R = 0.21, P < .0001), and negatively with creatinine clearance (R = -0.34, P < .0001). No correlation was found between time after transplantation and fluorescence in transplant recipients (R = -0.10, P = .10). Fluorescence in dialysis patients was positively correlated with duration of dialysis (R = 0.36, P = .042). Our results, like those of others, suggest that kidney transplantation does not fully correct increased AGE levels found in dialysis patients. The increased AGE levels in kidney transplant recipients cannot be explained by the differences in renal function alone. The availability of a simple, noninvasive method (AGE-Reader) to measure AGE accumulation may be used to monitor AGE accumulation in a clinical setting as well as in a study setting.

  9. Advanced glycation end products measured by skin autofluorescence in a population with central obesity.

    PubMed

    den Engelsen, Corine; van den Donk, Maureen; Gorter, Kees J; Salomé, Philippe L; Rutten, Guy E

    2012-01-01

    Accumulation of advanced glycation end products (AGEs) is enhanced by chronic hyperglycemia and oxidative stress and this process may contribute to the pathogenesis of vascular disease. Skin autofluorescence (AF), a measure of accumulation of AGEs in skin collagen, is associated with vascular disease in patients with diabetes.   Because central obesity enhances oxidative stress people with central obesity might already have increased accumulation of AGEs before diabetes or cardiovascular disease become manifest. To test this hypothesis, we compared the distribution of skin AF and its association with clinical and biochemical parameters in individuals with and without central obesity. Skin AF was measured by a validated AGE Reader in 816 persons with and 431 persons without central obesity, aged 20-70 y. Mean skin AF increased with age and smoking and was higher in centrally obese individuals compared with non-obese individuals (p = 0.001, after adjustment for age and smoking p = 0.13). Mean skin AF in the subgroups without central obesity and without other risk factors (n = 106), central obesity without other risk factors (n = 74) and central obesity with other risk factors (n = 742) was 1.63 ± 0.37, 1.74 ± 0.44 and 1.87 ± 0.43 AU, respectively (p for trend < 0.001, after adjustment for age and smoking p for trend = 0.12). In the group with central obesity age, current smoking, alcohol consumption, waist circumference, creatinine clearance and hs-CRP were independently associated with skin AF (R(2) = 29.4%). Waist circumference hardly contributed to the explained variance. The relationship between waist circumference and skin AF is not as obvious as we hypothesized.

  10. Advanced glycation end product associated skin autofluorescence: a mirror of vascular function?

    PubMed

    Hofmann, Britt; Adam, Anne-Catrin; Jacobs, Kathleen; Riemer, Marcus; Erbs, Christian; Bushnaq, Hasan; Simm, Andreas; Silber, Rolf-Edgar; Santos, Alexander Navarrete

    2013-01-01

    Advanced glycation end products (AGEs) seem to be involved in aging as well as in the development of cardiovascular diseases. During aging, AGEs accumulate in extracellular matrix proteins like collagen and contribute to vessel stiffness. Whether non-invasive measurement of AGE accumulation in the skin may reflect vessel function and vessel protein modification is unknown. Herein we set out to analyze the AGE-modifications in the collagens extracted from residual bypass graft material, the skin autofluorescence reflecting the accumulation of AGEs in the body as well as the pulse wave velocity reflecting vessel stiffness. Collagen types I and III (pepsin digestible collagen fraction) were isolated from the veins of 52 patients by proteolysis. The residual collagen fraction was further extracted by collagenase digestion. Collagen was quantified by hydroxyproline assay and AGEs by the AGE intrinsic fluorescence. Skin autofluorescence was measured with an autofluorescence reader; pulse wave velocity with the VICORDER. The collagen AGE autofluorescence in patient vein graft material increased with patient age. The pepsin digestible collagen fraction was significantly less modified in comparison to the collagenase digestible fraction. Decreasing amounts of extracted collagenase digestible collagen correspond with increasing AGE autofluorescence. Skin autofluorescence and vessel stiffness were significantly linked to the AGE autofluorescence of the collagenase digestible collagen fraction from graft material. In conclusion we have found that skin autofluorescence and pulse wave velocity as non-invasive parameters significantly correlate with the AGE contained in graft material and therefore are strong predictors of vessel AGE modifications in patients with coronary heart disease. Whether the analysis of the skin autofluorescence leads to an improvement of the risk stratification in patients suffering from cardiovascular disease has to be further tested.

  11. Advanced glycation end products induce moesin phosphorylation in murine retinal endothelium.

    PubMed

    Wang, Lingjun; Li, Qiaoqin; Du, Jing; Chen, Bo; Li, Qiang; Huang, Xuliang; Guo, Xiaohua; Huang, Qiaobing

    2012-02-01

    Increase in vascular permeability is the most important pathological event during the development of diabetic retinopathy. Deposition of advanced glycation end products (AGEs) plays a crucial role in the process of diabetes. This study was to investigate the role of moesin and its underlying signal transduction in retinal vascular hyper-permeability induced by AGE-modified mouse serum albumin (AGE-MSA). Female C57BL/6 mice were used to produce an AGE-treated model by intraperitoneal administration of AGE-MSA for seven consecutive days. The inner blood-retinal barrier was quantified by Evans blue leakage assay. Endothelial F-actin cytoskeleton in retinal vasculature was visualized by fluorescence probe staining. The expression and phosphorylation of moesin in retinal vessels were detected by RT-PCR and western blotting. Further studies were performed to explore the effects of Rho kinase (ROCK) and p38 MAPK pathway on the involvement of moesin in AGE-induced retinal vascular hyper-permeability response. Treatment with AGE-MSA significantly increased the permeability of the retinal microvessels and induced the disorganization of F-actin in retinal vascular endothelial cells. The threonine (T558) phosphorylation of moesin in retinal vessels was enhanced remarkably after AGE administration. The phosphorylation of moesin was attenuated by inhibitions of ROCK and p38 MAPK, while this treatment also prevented the dysfunction of inner blood-retinal barrier and the reorganization of F-actin in retinal vascular endothelial cells. These results demonstrate that moesin is involved in AGE-induced retinal vascular endothelial dysfunction and the phosphorylation of moesin is triggered via ROCK and p38 MAPK activation.

  12. Advanced glycation end products induce moesin phosphorylation in murine brain endothelium.

    PubMed

    Li, Qiaoqin; Liu, Hongxia; Du, Jing; Chen, Bo; Li, Qiang; Guo, Xiaohua; Huang, Xuliang; Huang, Qiaobing

    2011-02-10

    Advanced glycation end products (AGEs) have been found to play an important role in the development of diabetes, and AGE levels are correlated with the severity of diabetic complications. We have demonstrated that moesin, a protein linker between actin filaments and the plasma membrane, undergoes phosphorylation of its threonine 558 residue by AGE stimulation in human dermal microvascular endothelial cells through activation of p38 and Rho kinase (ROCK) pathways. In this study, we observed in situ whether AGEs caused phosphorylation of vascular endothelial cells in the brains of AGE-stimulated mice. The animals were injected with AGE-modified mouse serum albumin (AGE-MSA) for 7 consecutive days. Immunohistochemistry was conducted to assess the phosphorylation of moesin in brain vessels. The level of moesin protein phosphorylation was also assessed in cerebral microvessels by western blotting. The effects of p38 and ROCK activation were determined by application of a p38 inhibitor (SB203580) and a ROCK inhibitor (Y27632) at 30 min before each AGE administration. The results showed specific expression of moesin in murine brain vascular endothelial cells. AGE treatment induced a significant increase of threonine 558 phosphorylation in moesin, while inhibition of p38 and ROCK remarkably attenuated the phosphorylation of moesin. The level of moesin protein phosphorylation was also increased in cerebral microvessels, along with an increased permeability of the blood-brain barrier, while inhibition of the p38 and ROCK attenuated these responses. These results demonstrate that AGEs cause the phosphorylation of moesin in murine brain microvascular endothelial cells, with p38 and ROCK being involved in this process.

  13. Association between Advanced Glycation End Products and Impaired Fasting Glucose: Results from the SALIA Study

    PubMed Central

    Teichert, Tom; Hellwig, Anne; Peßler, Annette; Hellwig, Michael; Vossoughi, Mohammad; Sugiri, Dorothea; Vierkötter, Andrea; Schulte, Thomas; Freund, Juliane; Roden, Michael; Hoffmann, Barbara; Schikowski, Tamara; Luckhaus, Christian; Krämer, Ursula; Henle, Thomas; Herder, Christian

    2015-01-01

    Advanced glycation end products (AGEs) may contribute to the development of type 2 diabetes and related complications, whereas their role in the early deterioration of glycaemia is unknown. While previous studies used antibody-based methods to quantify AGEs, data from tandem mass spectrometry coupled liquid chromatography (LC-MS/MS)-based measurements are limited to patients with known diabetes. Here, we used the LC-MS/MS method to test the hypothesis that plasma AGE levels are higher in individuals with impaired fasting glucose (IFG) than in those with normal fasting glucose (NFG). Secondary aims were to assess correlations of plasma AGEs with quantitative markers of glucose metabolism and biomarkers of subclinical inflammation. This study included on 60 women with NFG or IFG (n = 30 each, mean age 74 years) from the German SALIA cohort. Plasma levels of free metabolites (3-deoxyfructose, 3-deoxypentosone, 3-deoxypentulose), two hydroimidazolones, oxidised adducts (carboxymethyllysine, carboxyethyllysine, methionine sulfoxide) and Nε-fructosyllysine were measured using LC-MS/MS. Plasma concentrations of all tested AGEs did not differ between the NFG and IFG groups (all p>0.05). Associations between plasma levels of AGEs and fasting glucose, insulin and HOMA-IR as a measure of insulin resistance were weak (r between -0.2 and 0.2, all p>0.05). The association between 3-deoxyglucosone-derived hydroimidazolone with several proinflammatory biomarkers disappeared upon adjustment for multiple testing. In conclusion, plasma AGEs assessed by LC-MS/MS were neither increased in IFG nor associated with parameters of glucose metabolism and subclinical inflammation in our study. Thus, these data argue against strong effects of AGEs in the early stages of deterioration of glucose metabolism. PMID:26018950

  14. Dietary advanced glycation end-products aggravate non-alcoholic fatty liver disease

    PubMed Central

    Leung, Christopher; Herath, Chandana B; Jia, Zhiyuan; Andrikopoulos, Sof; Brown, Bronwyn E; Davies, Michael J; Rivera, Leni R; Furness, John B; Forbes, Josephine M; Angus, Peter W

    2016-01-01

    AIM To determine if manipulation of dietary advanced glycation end product (AGE), intake affects non-alcoholic fatty liver disease (NAFLD) progression and whether these effects are mediated via RAGE. METHODS Male C57Bl6 mice were fed a high fat, high fructose, high cholesterol (HFHC) diet for 33 wk and compared with animals on normal chow. A third group were given a HFHC diet that was high in AGEs. Another group was given a HFHC diet that was marinated in vinegar to prevent the formation of AGEs. In a second experiment, RAGE KO animals were fed a HFHC diet or a high AGE HFHC diet and compared with wildtype controls. Hepatic biochemistry, histology, picrosirius red morphometry and hepatic mRNA were determined. RESULTS Long-term consumption of the HFHC diet generated significant steatohepatitis and fibrosis after 33 wk. In this model, hepatic 4-hydroxynonenal content (a marker of chronic oxidative stress), hepatocyte ballooning, picrosirius red staining, α-smooth muscle actin and collagen type 1A gene expression were all significantly increased. Increasing the AGE content of the HFHC diet by baking further increased these markers of liver damage, but this was abrogated by pre-marination in acetic acid. In response to the HFHC diet, RAGE-/- animals developed NASH of similar severity to RAGE+/+ animals but were protected from the additional harmful effects of the high AGE containing diet. Studies in isolated Kupffer cells showed that AGEs increase cell proliferation and oxidative stress, providing a likely mechanism through which these compounds contribute to liver injury. CONCLUSION In the HFHC model of NAFLD, manipulation of dietary AGEs modulates liver injury, inflammation, and liver fibrosis via a RAGE dependent pathway. This suggests that pharmacological and dietary strategies targeting the AGE/RAGE pathway could slow the progression of NAFLD. PMID:27672297

  15. Dysfunctional protection against advanced glycation due to thiamine metabolism abnormalities in gestational diabetes.

    PubMed

    Bartáková, Vendula; Pleskačová, Anna; Kuricová, Katarína; Pácal, Lukáš; Dvořáková, Veronika; Bělobrádková, Jana; Tomandlová, Marie; Tomandl, Josef; Kaňková, Kateřina

    2016-08-01

    While the pathogenic role of dicarbonyl stress and accelerated formation of advanced glycation end products (AGEs) to glucose intolerance and to the development of diabetic complications is well established, little is known about these processes in gestational diabetes mellitus (GDM), a condition pathogenically quite similar to type 2 diabetes. The aims of the present study were (i) to determine plasma thiamine and erythrocyte thiamine diphosphate (TDP) and transketolase (TKT) activity in pregnant women with and without GDM, (ii) to assess relationships between thiamine metabolism parameters and selected clinical, biochemical and anthropometric characteristics and, finally, (iii) to analyse relationship between variability in the genes involved in the regulation of transmembrane thiamine transport (i.e. SLC19A2 and SLC19A3) and relevant parameters of thiamine metabolism. We found significantly lower plasma BMI adjusted thiamine in women with GDM (P = 0.002, Mann-Whitney) while levels of erythrocyte TDP (an active TKT cofactor) in mid-trimester were significantly higher in GDM compared to controls (P = 0.04, Mann-Whitney). However, mid-gestational TKT activity - reflecting pentose phosphate pathway activity - did not differ between the two groups (P > 0.05, Mann-Whitney). Furthermore, we ascertained significant associations of postpartum TKT activity with SNPs SLC19A2 rs6656822 and SLC19A3 rs7567984 (P = 0.03 and P = 0.007, resp., Kruskal-Wallis). Our findings of increased thiamine delivery to the cells without concomitant increase of TKT activity in women with GDM therefore indicate possible pathogenic role of thiamine mishandling in GDM. Further studies are needed to determine its contribution to maternal and/or neonatal morbidity.

  16. An advanced glycation endproduct (AGE)-rich diet promotes accumulation of AGEs in Achilles tendon.

    PubMed

    Skovgaard, Dorthe; Svensson, Rene B; Scheijen, Jean; Eliasson, Pernilla; Mogensen, Pernille; Hag, Anne Mette F; Kjær, Michael; Schalkwijk, Casper G; Schjerling, Peter; Magnusson, Stig P; Couppé, Christian

    2017-03-01

    Advanced Glycation Endproducts (AGEs) accumulate in long-lived tissue proteins like collagen in bone and tendon causing modification of the biomechanical properties. This has been hypothesized to raise the risk of orthopedic injury such as bone fractures and tendon ruptures. We evaluated the relationship between AGE content in the diet and accumulation of AGEs in weight-bearing animal Achilles tendon. Two groups of mice (C57BL/6Ntac) were fed with either high-fat diet low in AGEs high-fat diet (HFD) (n = 14) or normal diet high in AGEs (ND) (n = 11). AGE content in ND was six to 50-fold higher than HFD The mice were sacrificed at week 40 and Achilles and tail tendons were carefully excised to compare weight and nonweight-bearing tendons. The amount of the AGEs carboxymethyllysine (CML), methylglyoxal-derived hydroimidazolone (MG-H1) and carboxyethyllysine (CEL) in Achilles and tail tendon was measured using ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and pentosidine with high-pressure liquid chromatography (HPLC) with fluorescent detection. AGEs in Achilles tendon were higher than in tail tendon for CML (P < 0.0001), CEL (P < 0.0001), MG-H1 and pentosidine (for both ND and HFD) (P < 0.0001). The AGE-rich diet (ND) resulted in an increase in CML (P < 0.0001), MG-H1 (P < 0.001) and pentosidine (P < 0.0001) but not CEL, in Achilles and tail tendon. This is the first study to provide evidence for AGE accumulation in injury-prone, weight-bearing Achilles tendon associated with intake of an AGE-rich diet. This indicates that food-derived AGEs may alter tendon properties and the development of tendon injuries.

  17. Advanced Glycation Endproducts Impair Endothelial Progenitor Cell Migration and Homing via Syndecan 4 Shedding.

    PubMed

    Xie, Jun; Li, Ran; Wu, Han; Chen, Jianzhou; Li, Guannan; Chen, Qinhua; Wei, Zhonghai; He, Guixin; Wang, Lian; Ferro, Albert; Xu, Biao

    2017-02-01

    Endothelial progenitor cells (EPCs) are a subtype of bone marrow-derived progenitor cells. Stromal cell-derived factor 1 (SDF-1)-mediated EPC mobilization from bone marrow to areas of ischemia plays an important role in angiogenesis. Previous studies have reported that advanced glycation endproducts (AGEs), which are important mediators of diabetes-related vascular pathology, may impair EPC migration and homing, but the mechanism is unclear. Syndecan-4 (synd4) is a ubiquitous heparan sulfate proteoglycan receptor on the cell surface, involved in SDF-1-dependent cell migration. The extracellular domain of synd4 (ext-synd4) is shed in the context of acute inflammation, but the shedding of ext-synd4 in response to AGEs is undefined. Here we investigated changes in ext-synd4 on EPCs in response to AGEs, focusing on the influence of impaired synd4 signaling on EPC migration and homing. We found decreased full length and increased residue of synd4 in cells incubated with AGEs, with concomitant increase in the soluble fragment of ext-synd4 in the cell medium. EPCs from patients with type 2 diabetes expressed less ext-synd4 as assessed by Western blotting. Flow cytometry analysis showed less ext-synd4 on circulating CD34(+) peripheral blood mononuclear cells, of which EPCs form a subgroup. We then explored the role of synd4 in EPC migration and homing. Impaired migration of synd4-deficient EPCs was observed by a 2D-chemotaxis slide. Furthermore, poor homing of synd4-/- EPCs was observed in a mouse model of lower limb ischemia. This study demonstrates that the shedding of synd4 from EPCs plays a key role in AGE-mediated dysfunction of EPC migration and homing. Stem Cells 2017;35:522-531.

  18. Increased levels of advanced glycation endproducts in the lenses and blood vessels of cigarette smokers.

    PubMed Central

    Nicholl, I. D.; Stitt, A. W.; Moore, J. E.; Ritchie, A. J.; Archer, D. B.; Bucala, R.

    1998-01-01

    BACKGROUND: Advanced glycation endproducts (AGEs) arise from the spontaneous reaction of reducing sugars with the amino groups of macromolecules. AGEs accumulate in tissue as a consequence of diabetes and aging and have been causally implicated in the pathogenesis of several of the end-organ complications of diabetes and aging, including cataract, atherosclerosis, and renal insufficiency. It has been recently proposed that components in mainstream cigarette smoke can react with plasma and extracellular matrix proteins to form covalent adducts with many of the properties of AGEs. We wished to ascertain whether AGEs or immunochemically related molecules are present at higher levels in the tissues of smokers. MATERIALS AND METHODS: Lens and coronary artery specimens from nondiabetic smokers and nondiabetic nonsmokers were examined by immunohistochemistry, immunoelectron microscopy, and ELISA employing several distinct anti-AGE antibodies. In addition, lenticular extracts were tested for AGE-associated fluorescence by fluorescence spectroscopy. RESULTS: Immunoreactive AGEs were present at significantly higher levels in the lenses and lenticular extracts of nondiabetic smokers (p < 0.003). Anti-AGE immunogold staining was diffusely distributed throughout lens fiber cells. AGE-associated fluorescence was significantly increased in the lenticular extracts of nondiabetic smokers (p = 0.005). AGE-immunoreactivity was significantly elevated in coronary arteries from nondiabetic smokers compared with nondiabetic nonsmokers (p = 0.015). CONCLUSIONS: AGEs or immunochemically related molecules are present at higher levels in the tissues of smokers than in nonsmokers, irrespective of diabetes. In view of previous reports implicating AGEs in a causal association with numerous pathologies, these findings have significant ramifications for understanding the etiopathology of diseases associated with smoking, the single greatest preventable cause of morbidity and mortality in the

  19. Advanced Glycation End-Products affect transcription factors regulating insulin gene expression

    SciTech Connect

    Puddu, A.; Storace, D.; Odetti, P.; Viviani, G.L.

    2010-04-23

    Advanced Glycation End-Products (AGEs) are generated by the covalent interaction of reducing sugars with proteins, lipids or nucleic acids. AGEs are implicated in diabetic complications and pancreatic {beta}-cell dysfunction. We previously demonstrated that exposure of the pancreatic islet cell line HIT-T15 to high concentrations of AGEs leads to a significant decrease of insulin secretion and content. Insulin gene transcription is positively regulated by the beta cell specific transcription factor PDX-1 (Pancreatic and Duodenal Homeobox-1). On the contrary, the forkhead transcription factor FoxO1 inhibits PDX-1 gene transcription. Activity of FoxO1 is regulated by post-translational modifications: phosphorylation deactivates FoxO1, and acetylation prevents FoxO1 ubiquitination. In this work we investigated whether AGEs affect expression and subcellular localization of PDX-1 and FoxO1. HIT-T15 cells were cultured for 5 days in presence of AGEs. Cells were then lysed and processed for subcellular fractionation. We determined intracellular insulin content, then we assessed the expression and subcellular localization of PDX-1, FoxO1, phosphoFoxO1 and acetylFoxO1. As expected intracellular insulin content was lower in HIT-T15 cells cultured with AGEs. The results showed that AGEs decreased expression and nuclear localization of PDX-1, reduced phosphorylation of FoxO1, and increased expression and acetylation of FoxO1. These results suggest that AGEs decrease insulin content unbalancing transcription factors regulating insulin gene expression.

  20. Advanced glycation end products, oxidative stress and metalloproteinases are altered in the cerebral microvasculature during aging.

    PubMed

    Safciuc, Florentina; Constantin, Alina; Manea, Adrian; Nicolae, Manuela; Popov, Doina; Raicu, Monica; Alexandru, Dorin; Constantinescu, Elena

    2007-11-01

    Biological aging is associated with an increased incidence of cerebrovascular disease. Recent findings indicate that oxidative stress promoting age-related changes of cerebral circulation are involved in neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease. The aim of this study was to evaluate the contribution of cerebral microvessels to the oxidative stress during brain aging, by: (i) assessment of precursors for advanced glycation end products (AGE) formation, (ii) activities of antioxidant enzymes, namely superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione disulfide reductase (GR), and (iii) the activities of metalloproteinases (MMPs), MMP-2 and MMP-9, involved in synaptogenesis and memory consolidation. The experiments were performed on two groups of male Wistar rats: 15 young (3-6 months old) and 15 aged (18-24 months old) animals. The cerebral microvessels were isolated by mechanical homogenization, the concentration of protein carbonyls and the activity of antioxidant enzymes were evaluated by spectrophotometry, and gelatin SDS-PAGE zymography was employed to evaluate MMP-2 and MMP-9 activities. The results showed that, by comparison with young rats, aged brain microvessels contain: (i) approximately 106 % increase of protein carbonyls production; (ii) approximately 68% higher GPx activity, unmodified activities of SOD and GR; (iii) approximately 30% diminishment in MMP-2 activity, and the specific occurrence of MMP-9 enzyme. The data suggest that the age-related changes of microvessels could increase the propensity for cerebral diseases and might represent, at least in part, a prerequisite for the deterioration of mental and physical status in the elderly.

  1. A receptor-based bioadsorbent to target advanced glycation end products in chronic kidney disease

    PubMed Central

    Zhang, Yangrong; Lapidos, Karen A.; Gal-Moscovici, Anca; Sprague, Stuart M.; Ameer, Guillermo A.

    2013-01-01

    The accumulation of advanced glycation end products (AGEs) has been reported to be a major contributor to chronic systemic inflammation. AGEs are not efficiently removed by hemodialysis or the kidney of a chronic kidney disease (CKD) patient. The goal of this study was to develop a receptor for AGEs (RAGE)-based bioadsorbent device that was capable of removing endogenous AGEs from human blood. The extracellular domain of RAGE was immobilized onto agarose beads to generate the bioadsorbent. The efficacy of AGE removal from saline, serum, and whole blood; biological effects of AGE reduction; and hemocompatibility and stability of the bioadsorbent were investigated. The bioadsorbent bound AGE-modified bovine serum albumin (AGE-BSA) with a binding capacity of 0.73 ± 0.07 mg AGE-BSA/ml bioadsorbent. The bioadsorbent significantly reduced the concentration of total AGEs in serum isolated from end stage kidney disease (ESKD) patients by 57%. AGE removal resulted in a significant reduction of vascular cell adhesion molecule-1 (VCAM-1) expression in human endothelial cells and abolishment of osteoclast formation in osteoclast progenitor cells. A hollow fiber device loaded with bioadsorbent reduced endogenous AGEs from recirculated blood to 36% of baseline levels with no significant changes in total protein and albumin concentration. The bioadsorbent maintained AGE-specific binding capacity after freeze-drying and storage for 1 year. This approach provides the foundation for further development of sRAGE-based extracorporeal therapies to selectively deplete serum AGEs from human blood and decrease inflammation in patients with diabetes and/or CKD. PMID:24206165

  2. Targeting receptor for advanced glycation end products (RAGE) expression induces apoptosis and inhibits prostate tumor growth

    SciTech Connect

    Elangovan, Indira; Thirugnanam, Sivasakthivel; Chen, Aoshuang; Zheng, Guoxing; Bosland, Maarten C.; Kajdacsy-Balla, Andre; Gnanasekar, Munirathinam

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer Targeting RAGE by RNAi induces apoptosis in prostate cancer cells. Black-Right-Pointing-Pointer Silencing RAGE expression abrogates rHMGB1 mediated cell proliferation. Black-Right-Pointing-Pointer Down regulation of RAGE by RNAi inhibits PSA secretion of prostate cancer cells. Black-Right-Pointing-Pointer Knock down of RAGE abrogates prostate tumor growth in vivo. Black-Right-Pointing-Pointer Disruption of RAGE expression in prostate tumor activates death receptors. -- Abstract: Expression of receptor for advanced glycation end products (RAGE) plays a key role in the progression of prostate cancer. However, the therapeutic potential of targeting RAGE expression in prostate cancer is not yet evaluated. Therefore in this study, we have investigated the effects of silencing the expression of RAGE by RNAi approach both in vitro and in vivo. The results of this study showed that down regulation of RAGE expression by RNAi inhibited the cell proliferation of androgen-dependent (LNCaP) and androgen-independent (DU-145) prostate cancer cells. Furthermore, targeting RAGE expression resulted in apoptotic elimination of these prostate cancer cells by activation of caspase-8 and caspase-3 death signaling. Of note, the levels of prostate specific antigen (PSA) were also reduced in LNCaP cells transfected with RAGE RNAi constructs. Importantly, the RAGE RNAi constructs when administered in nude mice bearing prostate tumors, inhibited the tumor growth by targeting the expression of RAGE, and its physiological ligand, HMGB1 and by up regulating death receptors DR4 and DR5 expression. Collectively, the results of this study for the first time show that targeting RAGE by RNAi may be a promising alternative therapeutic strategy for treating prostate cancer.

  3. Imaging receptor for advanced glycation end product expression in mouse model of hind limb ischemia

    PubMed Central

    2013-01-01

    Background The purpose of this study is to image the effect of diabetes on expression of receptor for advanced glycation endproducts (RAGE) in limb ischemia in live animals. Methods Male wild-type C57BL/6 mice were either made diabetic or left as control. Two months later, diabetic and non-diabetic mice underwent left femoral artery ligation. The right leg served as lesion control. Five days later, mice were injected with 15.1 ± 4.4 MBq 99mTc-anti-RAGE F(ab’)2 and 4 to 5 h later (blood pool clearance) underwent SPECT/CT imaging. At the completion of imaging, mice were euthanized, hind limbs counted and sectioned, and scans reconstructed. Regions of interest were drawn on serial transverse sections comprising the hind limbs and activity in millicuries summed and divided by the injected dose (ID). Quantitative histology was performed for RAGE staining and angiogenesis. Results Uptake of 99mTc-anti-RAGE F(ab')2 as %ID × 10−3 was higher in the left (ischemic) limbs for the diabetic mice (n = 8) compared to non-diabetic mice (n = 8) (1.20 ± 0.44% vs. 0.49 ± 0.40%; P = 0.0007) and corresponded to less angiogenesis in the diabetic mice. Uptake was also higher in the right limbs of diabetic compared to non-diabetic animals (0.82 ± 0.33% vs. 0.40 ± 0.14%; P = 0.0004). Conclusions These data show the feasibility of imaging and quantifying the effect of diabetes on RAGE expression in limb ischemia. PMID:23663412

  4. Molten Globule of Hemoglobin Proceeds into Aggregates and Advanced Glycated End Products

    PubMed Central

    Iram, Afshin; Alam, Tauqeer; Khan, Javed M.; Khan, Taqi A.; Khan, Rizwan H.; Naeem, Aabgeena

    2013-01-01

    Conformational alterations of bovine hemoglobin (Hb) upon sequential addition of glyoxal over a range of 0–90% v/v were investigated. At 20% v/v glyoxal, molten globule (MG) state of Hb was observed by altered tryptophan fluorescence, high ANS binding, existence of intact heme, native-like secondary structure as depicted by far-UV circular dichroism (CD) and ATR-FTIR spectra as well as loss in tertiary structure as confirmed by near-UV CD spectra. In addition, size exclusion chromatography analysis depicted that MG state at 20% v/v glyoxal corresponded to expanded pre-dissociated dimers. Aggregates of Hb were detected at 70% v/v glyoxal. These aggregates of Hb had altered tryptophan environment, low ANS binding, exposed heme, increased β-sheet secondary structure, loss in tertiary structure, enhanced thioflavin T (ThT) fluorescence and red shifted Congo Red (CR) absorbance. On incubating Hb with 30% v/v glyoxal for 0–20 days, advanced glycation end products (AGEs) were detected on day 20. These AGEs were characterised by enhanced tryptophan fluorescence at 450 nm, exposure of heme, increase in intermolecular β-sheets, enhanced ThT fluorescence and red shift in CR absorbance. Comet assay revealed aggregates and AGEs to be genotoxic in nature. Scanning electron microscopy confirmed the amorphous structure of aggregates and branched fibrils of AGEs. The transformation of α-helix to β-sheet usually alters the normal protein to amyloidogenic resulting in a variety of protein conformational disorders such as diabetes, prion and Huntington's. PMID:23991043

  5. Advanced glycation inhibition and protection against endothelial dysfunction induced by coumarins and procyanidins from Mammea neurophylla.

    PubMed

    Dang, Bach Tai; Gény, Charlotte; Blanchard, Patricia; Rouger, Caroline; Tonnerre, Pierre; Charreau, Béatrice; Rakolomalala, Gilbertine; Randriamboavonjy, Joseph Iharinjaka; Loirand, Gervaise; Pacaud, Pierre; Litaudon, Marc; Richomme, Pascal; Séraphin, Denis; Derbré, Séverine

    2014-07-01

    Advanced glycation end-products (AGEs) are associated with many pathogenic disorders such as pathogenesis of diabetes or endothelial dysfunction leading to cardiovascular events. Therefore, the identification of new anti-AGE molecules or extracts aims at preventing such pathologies. Many Clusiaceae and Calophyllaceae species are used in traditional medicines to treat arterial hypertension as well as diabetes. Focusing on these plant families, an anti-AGE plant screening allowed us to select Mammea neurophylla for further phytochemical and biological studies. Indeed, both DCM and MeOH stem bark extracts demonstrated in vitro their ability to prevent inflammation in endothelial cells and to reduce vasoconstriction. A bioguided fractionation of these extracts allowed us to point out 4-phenyl- and 4-(1-acetoxypropyl)coumarins and procyanidins as potent inhibitors of AGE formation, potentially preventing endothelial dysfunction. The fractionation steps also led to the isolation of two new compounds, namely neurophyllols A and B from the DCM bark extract together with thirteen known mammea A and E coumarins (mammea A/AA, mammea A/AB, mammea A/BA, mammea A/BB, mammea A/AA cycloD, mammea A/AB cycloD, disparinol B, mammea A/AB cycloE, ochrocarpin A, mammea A/AA cycloF, mammea A/AB cycloF, mammea E/BA, mammea E/BB) as well as δ-tocotrienol, xanthones (1-hydroxy-7-methoxyxanthone, 2-hydroxyxanthone) and triterpenes (friedelin and betulinic acid). During this study, R,S-asperphenamate, previously described from fungal origin was also purified.

  6. The impact of salsalate treatment on serum levels of advanced glycation end products in type 2 diabetes.

    PubMed

    Barzilay, Joshua I; Jablonski, Kathleen A; Fonseca, Vivian; Shoelson, Steven E; Goldfine, Allison B; Strauch, Christopher; Monnier, Vincent M

    2014-04-01

    OBJECTIVE Salsalate is a nonacetylated salicylate that lowers glucose levels in people with type 2 diabetes (T2D). Here we examined whether salsalate also lowered serum-protein-bound levels of early and advanced glycation end products (AGEs) that have been implicated in diabetic vascular complications. RESEARCH DESIGN AND METHODS Participants were from the Targeting Inflammation Using Salsalate for Type 2 Diabetes (TINSAL-T2D) study, which examined the impact of salsalate treatment on hemoglobin A1c (HbA1c) and a wide variety of other parameters. One hundred eighteen participants received salsalate, 3.5 g/day for 48 weeks, and 109 received placebo. Early glycation product levels (HbA1c and fructoselysine [measured as furosine]) and AGE levels (glyoxal and methylglyoxal hydroimidazolones [G-(1)H, MG-(1)H], carboxymethyllysine [CML], carboxyethyllysine [CEL], pentosidine) were measured in patient serum samples. RESULTS Forty-eight weeks of salsalate treatment lowered levels of HbA1c and serum furosine (P < 0.001) and CML compared with placebo. The AGEs CEL and G-(1)H and MG-(1)H levels were unchanged, whereas pentosidine levels increased more than twofold (P < 0.001). Among salsalate users, increases in adiponectin levels were associated with lower HbA1c levels during follow-up (P < 0.001). Changes in renal and inflammation factor levels were not associated with changes in levels of early or late glycation factors. Pentosidine level changes were unrelated to changes in levels of renal function, inflammation, or cytokines. CONCLUSIONS Salsalate therapy was associated with a reduction in early but not late glycation end products. There was a paradoxical increase in serum pentosidine levels suggestive of an increase in oxidative stress or decreased clearance of pentosidine precursor.

  7. Aspartic acid functions as carbonyl trapper to inhibit the formation of advanced glycation end products by chemical chaperone activity.

    PubMed

    Prasanna, Govindarajan; Saraswathi, N T

    2016-05-01

    Advanced glycation end products (AGEs) were implicated in pathology of numerous diseases. In this study, we present the bioactivity of aspartic acid (Asp) to inhibit the AGEs. Hemoglobin and bovine serum albumin (BSA) were glycated with glucose, fructose, and ribose in the presence and absence of Asp (100-200 μM). HbA1c inhibition was investigated using human blood and characterized by micro-column ion exchange chromatography. The effect of methyl glyoxal (MG) on hemoglobin and BSA was evaluated by fluorescence spectroscopy and gel electrophoresis. The effect of MG on red blood cells morphology was characterized by scanning electron micrographs. Molecular docking was performed on BSA with Asp. Asp is capable of inhibiting the formation of fluorescent AGEs by reacting with the reducing sugars. The presence of Asp as supplement in whole blood reduced the HbA1c% from 8.8 to 6.1. The presence of MG showed an increase in fluorescence and the presence of Asp inhibited the glycation thereby the fluorescence was quenched. MG also affected the electrophoretic mobility of hemoglobin and BSA by forming high molecular weight aggregates. Normal RBCs showed typical biconcave shape. MG modified RBCs showed twisted and elongated shape whereas the presence of ASP tends to protect RBC from twisting. Asp interacted with arginine residues of bovine serum albumin particularly ARG 194, ARG 198, and ARG 217 thereby stabilized the protein complex. We conclude that Asp has dual functions as a chemical chaperone to stabilize protein and as a dicarbonyl trapper, and thereby it can prevent the complications caused by glycation.

  8. Advanced Glycation End Products Evolution after Pancreas-Kidney Transplantation: Plasmatic and Cutaneous Assessments

    PubMed Central

    Oliveira, José C.; Vizcaíno, José Ramón; Gouveia, Carlos; Silva, Donzília; Henriques, António C.; Noronha, Irene L.; Rodrigues, Anabela

    2016-01-01

    Diabetes mellitus leads to increased Advanced Glycation End Products (AGE) production, which has been associated with secondary diabetic complications. Type 1 diabetic patients undergoing pancreas-kidney transplantation (SPKT) can restore normoglycemia and renal function, eventually decreasing AGE accumulation. We aimed to prospectively study AGE evolution after SPKT. Circulating AGE were assessed in 20 patients, at time 0 (T0), 3 months (T3), 6 months (T6), and 12 months (T12) after successful SPKT. Global AGE and carboxymethyllysine (CML) were analyzed, as well as advanced oxidation protein products (AOPP). Skin biopsies were obtained at T0 and T12. Immunohistochemistry with anti-AGE antibody evaluated skin AGE deposition. AGE mean values were 16.8 ± 6.4 μg/mL at T0; 17.1 ± 3.8 μg/mL at T3; 17.5 ± 5.6 μg/mL at T6; and 16.0 ± 5.2 μg/mL at T12. CML mean values were 0.94 ± 0.36 ng/mL at T0; 1.11 ± 0.48 ng/mL at T3; 0.99 ± 0.42 ng/mL at T6; and 0.78 ± 0.38 ng/mL at T12. AOPP mean values were 130.1 ± 76.8 μMol/L at T0; 137.3 ± 110.6 μMol/L at T3; 116.4 ± 51.2 μMol/L at T6; and 106.4 ± 57.9 μMol/L at T12. CML variation was significant (P = 0.022); AOPP variation was nearly significant (P = 0.076). Skin biopsies evolved mostly from a cytoplasmic diffuse to a peripheral interkeratinocytic immunoreaction pattern; in 7 cases, a reduction in AGE immunoreaction intensity was evident at T12. In conclusion, glycoxidation markers decrease, plasmatic and on tissues, may start early after SPKT. Studies with prolonged follow-up may confirm these data. PMID:26881017

  9. Effect of green tea extract on advanced glycation and cross-linking of tail tendon collagen in streptozotocin induced diabetic rats.

    PubMed

    Babu, Pon Velayutham Anandh; Sabitha, Kuruvimalai Ekambaram; Shyamaladevi, Chennam Srinivasulu

    2008-01-01

    Diabetes leads to modification of collagen such as advanced glycation and cross-linking which play an important role in the pathogenesis of diabetes mellitus. We have investigated the effect of green tea on modification of collagen in streptozotocin (60 mg/kg body weight) induced diabetic rats. To investigate the therapeutic effect of green tea, treatment was begun six weeks after the onset of diabetes and green tea extract (300 mg/kg body weight) was given orally for 4 weeks. The collagen content, extent of advanced glycation, advanced glycation end products (AGE) and cross-linking of tail tendon collagen were investigated. Green tea reduced the tail tendon collagen content which increased in diabetic rats. Accelerated advanced glycation and AGE in diabetic animals, as detected by Ehrlich's-positive material and collagen linked fluorescence respectively were reduced significantly by green tea. The solubility of tail tendon collagen decreased significantly in diabetic rats indicating a remarkable increase in the cross-linking, whereas green tea increases the solubility of collagen in diabetic rats. The present study reveals that green tea is effective in reducing the modification of tail tendon collagen in diabetic rats. Thus green tea may have a therapeutic effect in the treatment of glycation induced complications of diabetes.

  10. The Receptor for Advanced Glycation End Products (RAGE) Is Associated with Persistent Atrial Fibrillation

    PubMed Central

    Lancefield, Terase F.; Patel, Sheila K.; Freeman, Melanie; Velkoska, Elena; Wai, Bryan; Srivastava, Piyush M.; Horrigan, Mark; Farouque, Omar; Burrell, Louise M.

    2016-01-01

    Objective Upregulation of the receptor for advanced glycation end products (RAGE) has been proposed as a pathophysiological mechanism underlying the development of atrial fibrillation (AF). We sought to investigate if soluble RAGE levels are associated with AF in Caucasian patients. Methods Patients (n = 587) were prospectively recruited and serum levels of soluble RAGE (sRAGE) and endogenous secretory RAGE (esRAGE) measured. The patients included 527 with sinus rhythm, 32 with persistent AF (duration >7 days, n = 32) and 28 with paroxysmal AF (duration <7 days, n = 28). Results Patients with AF were older and had a greater prevalence of heart failure than patients in sinus rhythm. Circulating RAGE levels were higher in patients with persistent AF [median sRAGE 1190 (724–2041) pg/ml and median esRAGE 452 (288–932) pg/ml] compared with paroxysmal AF [sRAGE 799 (583–1033) pg/ml and esRAGE 279 (201–433) pg/ml, p ≤ 0.01] or sinus rhythm [sRAGE 782 (576–1039) pg/ml and esRAGE 289 (192–412) pg/ml, p < 0.001]. In multivariable logistic regression analysis, independent predictors of persistent AF were age, heart failure, sRAGE [odds ratio 1.1 per 100 pg/ml, 95% confidence interval (CI) 1.0–1.1, p = 0.001] and esRAGE [odds ratio 1.3 per 100 pg/ml, 95% CI 1.1–1.4, p < 0.001]. Heart failure and age were the only independent predictors of paroxysmal AF. In AF patients, sRAGE [odds ratio 1.1 per 100 pg/ml, 95% CI 1.1–1.2, p = 0.007] and esRAGE [odds ratio 1.3 per 100 pg/ml, 95% CI 1.0–1.5, p = 0.017] independently predicted persistent compared with paroxysmal AF. Conclusions Soluble RAGE is elevated in Caucasian patients with AF, and both sRAGE and esRAGE predict the presence of persistent AF. PMID:27627677

  11. Association of genetic variants in the receptor for advanced glycation end products gene with diabetic retinopathy

    PubMed Central

    Yu, Weihong; Yang, Jingyun; Sui, Wenda; Qu, Bin; Huang, Ping; Chen, Youxin

    2016-01-01

    Abstract Background: Diabetic retinopathy (DR) is a major sight-threatening diabetic complication. Previous studies have examined the association of DR with multiple genetic variants in the receptor for advanced glycation end products (RAGE) gene, with inconsistent results. Objective: To perform a systematic literature search and conduct meta-analyses to examine the association of genetic variants in RAGE with DR. Data sources: PubMed, Cochrane Library, Embase, Google Scholar, and HuGE. Study eligibility criteria and participants: Studies were on human subjects; the studies were case–control ones and included subjects who had DR and those who did not have DR; and the studies provided genotype data for genetic variants in RAGE, separately for subjects who had and did not have DR, or provided odds ratios (ORs) and the 95% confidence intervals (CIs), or provided sufficient data for the calculation of OR and the 95% CI. Study appraisal and synthesis methods: We used OR as a measure of association, and used random-effects model in all the meta-analyses. Between-study heterogeneity was assessed using I2, and publication bias was evaluated using Egger test. Results: A total of 13 studies met the eligibility criteria and were included in our analyses. We found that Gly82Ser was significantly associated with DR (OR = 2.40, 95% CI: 1.46–3.97; P = 0.001) using a recessive model. -374T/A also showed significant association with DR under a dominant model (OR = 1.21, 95% CI: 1.03–1.43; P = 0.023). We did not find a significant association of DR with other genetic variants in RAGE. Limitations: The number of included studies is small for some genetic variants; duration of diabetes varied across studies; most studies were conducted in Asia; and it is not clear whether the observed association can be generalized to other ethnicities; and we could not control for other potential confounding factors. Conclusions and implications of key findings: We found that Gly82Ser in RAGE

  12. Advanced glycation endproducts are increased in rheumatoid arthritis patients with controlled disease

    PubMed Central

    2011-01-01

    Introduction Advanced glycation end products (AGEs) are produced and can accumulate during chronic inflammation, as might be present in patients with rheumatoid arthritis (RA). AGEs are involved in the development of cardiovascular disease. The aim of this study is to evaluate whether AGEs are increased in patients with long-standing RA and whether AGE accumulation is related to disease activity, disease severity and measures of (premature) atherosclerosis, such as endothelial activation, endothelial dysfunction and intima media thickness (IMT). Methods In a cross-sectional study, 49 consecutive RA patients with longstanding disease (median disease duration of 12.3 years (range 9.3 to 15.1)), receiving standard of care, were included and compared with 49 age- and sex-matched healthy controls (HC). AGEs were determined by skin autofluorescence. Disease activity was evaluated by the Disease Activity Score of 28 joints (DAS-28) score and joint damage by modified Sharp-v.d. Heijde score. Endothelial activation (soluble vascular cellular adhesion molecule-1) sVCAM-1, von Willebrand factor (vWF), thrombomodulin), endothelial dysfunction (determined by small artery elasticity (SAE)) and IMT were measured and related to AGE accumulation. Results AGEs were increased in RA patients (median 2.4 arbitrary units (a.u.), range 1.6 to 4.2) compared to HC (2.2, 1.3 to 3.8). RA patients had a DAS-28 score of 2.9 (0.8 to 6.9) and a modified Sharp-v.d. Heijde score of 19 (0 to 103). sVCAM-1 and vWF levels were higher in RA patients. SAE was significantly decreased in RA (3.9 ml/mmHg (1.4 to 12.2) vs. 6.1 in HC (1.7 to 12.9). IMT did not differ between the two groups. Combining both groups' AGEs correlated with vWF, sVCAM-1 and IMT, and was inversely related to SAE. In RA, AGEs had an inverse relation with SAE, but did not relate to disease activity or radiological damage. In multivariate analysis for both groups, smoking, glucose levels, vWF, SAE and male gender were significantly

  13. Soluble receptor for advanced glycation end products and risk of liver cancer

    PubMed Central

    Moy, Kristin A.; Jiao, Li; Freedman, Neal D.; Weinstein, Stephanie J.; Sinha, Rashmi; Virtamo, Jarmo; Albanes, Demetrius; Stolzenberg-Solomon, Rachael Z.

    2013-01-01

    Binding of advanced glycation end products (AGEs) to their receptor (RAGE) increases oxidative stress and inflammation, and may be involved in liver injury and subsequent carcinogenesis. Soluble RAGE (sRAGE) may neutralize the effects mediated by AGEs/RAGE complex. Epidemiologic studies examining sRAGE or AGEs in association with liver cancer are lacking. We examined the associations between prediagnostic serum concentrations of sRAGE or Nε-(carboxymethyl)-lysine (CML)-AGE and hepatocellular carcinoma (HCC) in a case-cohort study within a cohort of 29,133 Finnish male smokers who completed questionnaires and provided a fasting blood sample in 1985–1988. During follow-up beginning 5 years after enrollment through April 2006, 145 liver cancers occurred. Serum concentrations of sRAGE, CML-AGE, glucose, and insulin were measured in cases and 485 randomly sampled cohort participants. Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) were available on most cases and a subset of the study population. Weighted Cox proportional hazards regression was used to calculate relative risks (RR) and 95% confidence intervals (CI), adjusted for age, years of smoking, and body mass index. sRAGE and CML-AGE concentrations were inversely associated with liver cancer (sRAGE: RR, highest versus lowest tertile, 0.77; 95% CI, 0.48–1.24; Ptrend=0.28; continuous RR, 0.86; 95% CI, 0.75–0.99; CML-AGE: RR, highest versus lowest tertile, 0.19; 95% CI, 0.10–0.35; Ptrend <0.0001; continuous RR, 0.74; 95% CI, 0.65–0.84). Further adjustment for glucose and insulin, or exclusion of cases with chronic HBV or HCV, did not change the associations. Conclusion Our results support the hypothesis that sRAGE is inversely associated with liver cancer. The findings need confirmation, particularly in populations that include women and non-smokers. PMID:23325627

  14. Cinnamaldehyde and nitric oxide attenuate advanced glycation end products-induced the Jak/STAT signaling in human renal tubular cells.

    PubMed

    Huang, Jau-Shyang; Lee, Ying-Ho; Chuang, Lea-Yea; Guh, Jinn-Yuh; Hwang, Jean-Yu

    2015-06-01

    Cinnamaldehyde is a major and a bioactive compound isolated from the leaves of Cinnamomum osmophloeum kaneh. It possesses anti-diabetic properties in vitro and in vivo and has anti-inflammatory and anti-cancer effects. To explore whether cinnamaldehyde was linked to altered advanced glycation end products (AGE)-mediated diabetic nephropathy, the molecular mechanisms of cinnamaldehyde responsible for inhibition of AGE-reduced nitric oxide (NO) bioactivity in human renal proximal tubular cells were examined. We found that raising the ambient AGE concentration causes a dose-dependent decrease in NO generation. Cinnamaldehyde significantly reverses AGE-inhibited NO generation and induces high levels of cGMP synthesis and PKG activation. Treatments with cinnamaldehyde, the NO donor S-nitroso-N-acetylpenicillamine, and the JAK2 inhibitor AG490 markedly attenuated AGE-inhibited NOS protein levels and NO generation. Moreover, AGE-induced the JAK2-STAT1/STAT3 activation, RAGE/p27(Kip1) /collagen IV protein levels, and cellular hypertrophy were reversed by cinnamaldehyde. The ability of cinnamaldehyde to suppress STAT activation was also verified by the observation that it significantly increased SCOS-3 protein level. These findings indicate for the first time that in the presence of cinnamaldehyde, the suppression of AGE-induced biological responses is probably mediated by inactivating the JAK2-STAT1/STAT3 cascade or activating the NO pathway.

  15. Advanced Glycation End Products (AGE) Potently Induce Autophagy through Activation of RAF Protein Kinase and Nuclear Factor κB (NF-κB).

    PubMed

    Verma, Neeharika; Manna, Sunil K

    2016-01-15

    Advanced glycation end products (AGE) accumulate in diabetic patients and aging people because of high amounts of three- or four-carbon sugars derived from glucose, thereby causing multiple consequences, including inflammation, apoptosis, obesity, and age-related disorders. It is important to understand the mechanism of AGE-mediated signaling leading to the activation of autophagy (self-eating) that might result in obesity. We detected AGE as one of the potent inducers of autophagy compared with doxorubicin and TNF. AGE-mediated autophagy is inhibited by suppression of PI3K and potentiated by the autophagosome maturation blocker bafilomycin. It increases autophagy in different cell types, and that correlates with the expression of its receptor, receptor for AGE. LC3B, the marker for autophagosomes, is shown to increase upon AGE stimulation. AGE-mediated autophagy is partially suppressed by inhibitor of NF-κB, PKC, or ERK alone and significantly in combination. AGE increases sterol regulatory element binding protein activity, which leads to an increase in lipogenesis. Although AGE-mediated lipogenesis is affected by autophagy inhibitors, AGE-mediated autophagy is not influenced by lipogenesis inhibitors, suggesting that the turnover of lipid droplets overcomes the autophagic clearance. For the first time, we provide data showing that AGE induces several cell signaling cascades, like NF-κB, PKC, ERK, and MAPK, that are involved in autophagy and simultaneously help with the accumulation of lipid droplets that are not cleared effectively by autophagy, therefore causing obesity.

  16. Crosstalk between advanced glycation end products (AGEs)-receptor RAGE axis and dipeptidyl peptidase-4-incretin system in diabetic vascular complications.

    PubMed

    Yamagishi, Sho-ichi; Fukami, Kei; Matsui, Takanori

    2015-01-13

    Advanced glycation end products (AGEs) consist of heterogenous group of macroprotein derivatives, which are formed by non-enzymatic reaction between reducing sugars and amino groups of proteins, lipids and nucleic acids, and whose process has progressed at an accelerated rate under diabetes. Non-enzymatic glycation and cross-linking of protein alter its structural integrity and function, contributing to the aging of macromolecules. Furthermore, engagement of receptor for AGEs (RAGE) with AGEs elicits oxidative stress generation and subsequently evokes proliferative, inflammatory, and fibrotic reactions in a variety of cells. Indeed, accumulating evidence has suggested the active involvement of accumulation of AGEs in diabetes-associated disorders such as diabetic microangiopathy, atherosclerotic cardiovascular diseases, Alzheimer's disease and osteoporosis. Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are incretins, gut hormones secreted from the intestine in response to food intake, both of which augment glucose-induced insulin release, suppress glucagon secretion, and slow gastric emptying. Since GLP-1 and GIP are rapidly degraded and inactivated by dipeptidyl peptidase-4 (DPP-4), inhibition of DPP-4 and/or DPP-4-resistant GLP-1 analogues have been proposed as a potential target for the treatment of diabetes. Recently, DPP-4 has been shown to cleave multiple peptides, and blockade of DPP-4 could exert diverse biological actions in GLP-1- or GIP-independent manner. This article summarizes the crosstalk between AGEs-RAGE axis and DPP-4-incretin system in the development and progression of diabetes-associated disorders and its therapeutic intervention, especially focusing on diabetic vascular complications.

  17. Effects of combined lipoic acid and pyridoxine on albuminuria, advanced glycation end-products, and blood pressure in diabetic nephropathy.

    PubMed

    Noori, Nazanin; Tabibi, Hadi; Hosseinpanah, Farhad; Hedayati, Mehdi; Nafar, Mohsen

    2013-01-01

    This study was designed to investigate the effects of combined administration of lipoic acid and pyridoxine on albuminuria, oxidative stress, blood pressure, serum advanced glycation end-products, nitric oxide (NO), and endothelin-1 in patients with diabetic nephropathy. Thirty-four patients were randomly assigned to either a supplement group or a placebo group. The patients in the supplement group received 800 mg lipoic acid and 80 mg pyridoxine daily for 12 weeks, whereas the placebo group received corresponding placebos. Urinary albumin, serum malondialdehyde (MDA), and systolic blood pressure decreased significantly in the supplement group compared to the placebo group (p < 0.05). Serum NO increased in the supplement group compared to the placebo group (p < 0.05). Serum pentosidine and carboxymethyl lysine decreased significantly in the supplement group at the end of week 12 compared to baseline (p < 0.05). No statistically significant differences were observed between the two groups in mean changes of serum endothelin-1, glucose, and diastolic blood pressure. The present study indicates that combined administration of lipoic acid and pyridoxine improves albuminuria in patients with diabetic nephropathy by reducing oxidative stress, advanced glycation end-products, and systolic blood pressure. The reduction in microalbuminuria may be of benefit in retarding the progression of diabetic nephropathy.

  18. Inhibition of human muscle-specific enolase by methylglyoxal and irreversible formation of advanced glycation end products.

    PubMed

    Pietkiewicz, Jadwiga; Gamian, Andrzej; Staniszewska, Magdalena; Danielewicz, Regina

    2009-04-01

    Methylglyoxal (MG) was studied as an inhibitor and effective glycating factor of human muscle-specific enolase. The inhibition was carried out by the use of a preincubation procedure in the absence of substrate. Experiments were performed in anionic and cationic buffers and showed that inhibition of enolase by methylglyoxal and formation of enolase-derived glycation products arose more effectively in slight alkaline conditions and in the presence of inorganic phosphate. Incubation of 15 micromolar solutions of the enzyme with 2 mM, 3.1 mM and 4.34 mM MG in 100 mM phosphate buffer pH 7.4 for 3 h caused the loss a 32%, 55% and 82% of initial specific activity, respectively. The effect of MG on catalytic properties of enolase was investigated. The enzyme changed the K(M) value for glycolytic substrate 2-phospho-D-glycerate (2-PGA) from 0.2 mM for native enzyme to 0.66 mM in the presence of MG. The affinity of enolase for gluconeogenic substrate phosphoenolpyruvate altered after preincubation with MG in the same manner, but less intensively. MG has no effect on V(max) and optimal pH values. Incubation of enolase with MG for 0-48 h generated high molecular weight protein derivatives. Advanced glycation end products (AGEs) were resistant to proteolytic degradation by trypsin. Magnesium ions enhanced the enzyme inactivation by MG and facilitated AGEs formation. However, the protection for this inhibition in the presence of 2-PGA as glycolytic substrate was observed and AGEs were less effectively formed under these conditions.

  19. Formation of Fructose-Mediated Advanced Glycation End Products and Their Roles in Metabolic and Inflammatory Diseases.

    PubMed

    Gugliucci, Alejandro

    2017-01-01

    Fructose is associated with the biochemical alterations that promote the development of metabolic syndrome (MetS), nonalcoholic fatty liver disease, and type 2 diabetes. Its consumption has increased in parallel with MetS. It is metabolized by the liver, where it stimulates de novo lipogenesis. The triglycerides synthesized lead to hepatic insulin resistance and dyslipidemia. Fructose-derived advanced glycation end products (AGEs) may be involved via the Maillard reaction. Fructose has not been a main focus of glycation research because of the difficulty in measuring its adducts, and, more importantly, because although it is 10 times more reactive than glucose, its plasma concentration is only 1% of that of glucose. In this focused review, I summarize exogenous and endogenous fructose metabolism, fructose glycation, and in vitro, animal, and human data. Fructose is elevated in several tissues of diabetic patients where the polyol pathway is active, reaching the same order of magnitude as glucose. It is plausible that the high reactivity of fructose, directly or via its metabolites, may contribute to the formation of intracellular AGEs and to vascular complications. The evidence, however, is still unconvincing. Two areas that have been overlooked so far and should be actively explored include the following: 1) enteral formation of fructose AGEs, generating an inflammatory response to the receptor for AGEs (which may explain the strong association between fructose consumption and asthma, chronic bronchitis, and arthritis); and 2) inactivation of hepatic AMP-activated protein kinase by a fructose-mediated increase in methylglyoxal flux (perpetuating lipogenesis, fatty liver, and insulin resistance). If proven correct, these mechanisms would put the fructose-mediated Maillard reaction in the limelight again as a contributing factor in chronic inflammatory diseases and MetS.

  20. Advanced glycation end-products produced systemically and by macrophages: A common contributor to inflammation and degenerative diseases.

    PubMed

    Byun, Kyunghee; Yoo, YongCheol; Son, Myeongjoo; Lee, Jaesuk; Jeong, Goo-Bo; Park, Young Mok; Salekdeh, Ghasem Hosseini; Lee, Bonghee

    2017-02-13

    Advanced glycation end products (AGEs) and their receptor have been implicated in the progressions of many intractable diseases, such as diabetes and atherosclerosis, and are also critical for pathologic changes in chronic degenerative diseases, such as Alzheimer's disease, Parkinson's disease, and alcoholic brain damage. Recently activated macrophages were found to be a source of AGEs, and the most abundant form of AGEs, AGE-albumin excreted by macrophages has been implicated in these diseases and to act through common pathways. AGEs inhibition has been shown to prevent the pathogenesis of AGEs-related diseases in human, and therapeutic advances have resulted in several agents that prevent their adverse effects. Recently, anti-inflammatory molecules that inhibit AGEs have been shown to be good candidates for ameliorating diabetic complications as well as degenerative diseases. This review was undertaken to present, discuss, and clarify current understanding regarding AGEs formation in association with macrophages, different diseases, therapeutic and diagnostic strategy and links with RAGE inhibition.

  1. Stilbene glucoside from Polygonum multiflorum Thunb.: a novel natural inhibitor of advanced glycation end product formation by trapping of methylglyoxal.

    PubMed

    Lv, Lishuang; Shao, Xi; Wang, Liyan; Huang, Derong; Ho, Chi-Tang; Sang, Shengmin

    2010-02-24

    Methylglyoxal (MGO), the reactive dicarbonyl intermediate generated during the nonenzymatic glycation between reducing sugars and amino groups of proteins, lipids, and DNA, is the precursor of advanced glycation end products (AGEs). Many studies have shown that AGEs play a major pathogenic role in diabetes and its complications. This study found that 2,3,5,4'-tetrahydroxystilbene 2-O-beta-D-glucoside (THSG), the major bioactive compound from Polygonum multiflorum Thunb., can efficiently inhibit the formation of AGEs in a dose-dependent manner by trapping reactive MGO under physiological conditions (pH 7.4, 37 degrees C). More than 60% MGO was trapped by THSG within 24 h, which was much more effective than resveratrol and its methylated derivative, pterostilbene, the two major bioactive dietary stilbenes. The major mono- and di-MGO adducts of THSG were successfully purified and found to be mixtures of tautomers. LC-MS and NMR data showed that positions 4 and 6 of the A ring were the major active sites for trapping MGO. It was also found that THSG could significantly inhibit the formation of AGEs in the human serum albumin (HSA)-MGO assay and both mono- and di-MGO adducts of THSG were detected in this assay using LC-MS. The results suggest that the ability of THSG to trap reactive dicarbonyl species makes it a potential natural inhibitor of AGEs.

  2. Predictive value of advanced glycation end products for the development of post-infarction heart failure: a preliminary report

    PubMed Central

    2012-01-01

    Background Since post-infarction heart failure (HF) determines a great morbidity and mortality, and given the physiopathology implications of advanced glycation end products (AGE) in the genesis of myocardial dysfunction, it was intended to analyze the prognostic value of these molecules in order to predict post-infarction HF development. Methods A prospective clinical study in patients after first acute coronary syndrome was conducted. The follow-up period was consisted in 1 year. In 194 patients consecutively admitted in the coronary unit for myocardial infarct fluorescent AGE levels were measured. The association between glycaemic parameters and the development of post-infarction HF were analyzed in those patients. Finally, we identified the variables with independent predictor value by performing a multivariate analysis of Hazard ratio for Cox regression. Results Eleven out of 194 patients (5.6%) developed HF during follow-up (median: 1.0 years [0.8 - 1.5 years]). Even though basal glucose, fructosamine and glycated haemoglobin were significant predictive factors in the univariate analysis, after being adjusted by confounding variables and AGE they lost their statistical signification. Only AGE (Hazard Ratio 1.016, IC 95%: 1.006-1.026; p<0,001), together with NT-proBNP and the infarct extension were predictors for post-infarction HF development, where AGE levels over the median value 5-fold increased the risk of HF development during follow-up. Conclusions AGE are an independent marker of post-infarction HF development risk. PMID:22909322

  3. Role of advanced glycation end products (AGEs) and receptor for AGEs (RAGE) in vascular damage in diabetes.

    PubMed

    Yamagishi, Sho-ichi

    2011-04-01

    A non-enzymatic reaction between ketones or aldehydes and the amino groups of proteins, lipids and nucleic acids contributes to the aging of macromolecules and to the development and progression of various age-related disorders such as vascular complications of diabetes, Alzheimer's disease, cancer growth and metastasis, insulin resistance and degenerative bone disease. Under hyperglycemic and/or oxidative stress conditions, this process begins with the conversion of reversible Schiff base adducts, and then to more stable, covalently-bound Amadori rearrangement products. Over a course of days to weeks, these early glycation products undergo further reactions and rearrangements to become irreversibly crossed-linked, fluorescent protein derivatives termed advanced glycation end products (AGEs). There is a growing body of evidence that AGE and their receptor RAGE (receptor for AGEs) interaction elicits oxidative stress, inflammatory reactions and thrombosis, thereby being involved in vascular aging and damage. These observations suggest that the AGE-RAGE system is a novel therapeutic target for preventing diabetic vascular complications. In this paper, we review the pathophysiological role of the AGE-RAGE-oxidative stress system and its therapeutic intervention in vascular damage in diabetes. We also discuss here the potential utility of the restriction of food-derived AGEs in diabetic vascular complications.

  4. Diet-derived advanced glycation end products or lipofuscin disrupts proteostasis and reduces life span in Drosophila melanogaster.

    PubMed

    Tsakiri, Eleni N; Iliaki, Kalliopi K; Höhn, Annika; Grimm, Stefanie; Papassideri, Issidora S; Grune, Tilman; Trougakos, Ioannis P

    2013-12-01

    Advanced glycation end product (AGE)-modified proteins are formed by the nonenzymatic glycation of free amino groups of proteins and, along with lipofuscin (a highly oxidized aggregate of covalently cross-linked proteins, sugars, and lipids), have been found to accumulate during aging and in several age-related diseases. As the in vivo effects of diet-derived AGEs or lipofuscin remain elusive, we sought to study the impact of oral administration of glucose-, fructose-, or ribose-modified albumin or of artificial lipofuscin in a genetically tractable model organism. We report herein that continuous feeding of young Drosophila flies with culture medium enriched in AGEs or in lipofuscin resulted in reduced locomotor performance and in accelerated rates of AGE-modified proteins and carbonylated proteins accumulation in the somatic tissues and hemolymph of flies, as well as in a significant reduction of flies health span and life span. These phenotypic effects were accompanied by reduced proteasome peptidase activities in both the hemolymph and the somatic tissues of flies and higher levels of oxidative stress; furthermore, oral administration of AGEs or lipofuscin in flies triggered an upregulation of the lysosomal cathepsin B, L activities. Finally, RNAi-mediated cathepsin D knockdown reduced flies longevity and significantly augmented the deleterious effects of AGEs and lipofuscin, indicating that lysosomal cathepsins reduce the toxicity of diet-derived AGEs or lipofuscin. Our in vivo studies demonstrate that chronic ingestion of AGEs or lipofuscin disrupts proteostasis and accelerates the functional decline that occurs with normal aging.

  5. Formation of Pentosidine Cross-Linking in Myoglobin by Glyoxal: Detection of Fluorescent Advanced Glycation End Product.

    PubMed

    Banerjee, Sauradipta

    2017-03-15

    Glyoxal, a reactive α-oxoaldehyde, increases in diabetic condition and reacts with proteins to form advanced glycation end products (AGEs) following Maillard-like reaction. Considering the significance of protein modification by glyoxal-derived AGEs, we investigated the in vitro effect of glyoxal (200 μM) on the monomeric heme protein myoglobin (Mb) (100 μM) after incubation for one week at 25 °C. Glyoxal-treated Mb exhibited increased absorbance around the Soret region, decreased α-helicity and thermal stability compared to control Mb. Intrinsic fluorescence spectrum of the treated Mb showed an additional signal in the 400-500 nm region on excitation at 280 nm that was absent in control Mb. When excited at 335 nm, the glyoxal-treated sample gave a strong fluorescence indicating AGE formation. Mass spectrometric studies revealed formation of glyoxal-derived fluorescent AGE adduct pentosidine between Lys-145 and Arg-139 residues of Mb. Other than pentosidine, additional AGE adducts, namely, carboxymethyllysine at Lys-133, hydroimidazolone at Arg-31 and pyrrolidone-carboxymethyllysine at Lys-145 were also detected. Lys-145 was thus found to contain two different types of AGE adducts, indicating the heterogeneous nature of in vitro glycation reaction. AGE-induced protein modifications might be associated with complications in disease conditions.

  6. Antihyperglycemic activity and inhibition of advanced glycation end product formation by Cuminum cyminum in streptozotocin induced diabetic rats.

    PubMed

    Jagtap, A G; Patil, P B

    2010-01-01

    Cuminum cyminum is widely used as a spice in many countries. The aim of the present study was to investigate the effect of methanolic extract of seeds of C. cyminum (CC) on diabetes, oxidative stress and formation of advanced glycated end products (AGE) and obtain comparison with glibenclamide. In vitro studies indicated that CC inhibited free radicals and AGE formation. Treatment of streptozotocin-diabetic rats with CC and glibenclamide for 28 days caused a reduction in blood glucose, glycosylated hemoglobin, creatinine, blood urea nitrogen and improved serum insulin and glycogen (liver and skeletal muscle) content when compared to diabetic control rats. Significant reduction in renal oxidative stress and AGE was observed with CC when compared to diabetic control and glibenclamide. CC and glibenclamide improved antioxidant status in kidney and pancreas of diabetic rats. Diabetic rats showed increase in rat tail tendon collagen, glycated collagen, collagen linked fluorescence and reduction in pepsin digestion. Treatment with CC significantly improved these parameters when compared to diabetic control and glibenclamide group. Though the antidiabetic effect of CC was comparable to glibenclamide it had better effect in controlling oxidative stress and inhibiting the AGE formation, which are implicated in the pathogenesis of diabetic microvascular complications.

  7. Receptor for advanced glycation end product blockade enhances the chemotherapeutic effect of cisplatin in tongue squamous cell carcinoma by reducing autophagy and modulating the Wnt pathway.

    PubMed

    Zhao, Ziming; Wang, Hongyu; Zhang, Liao; Mei, Xifan; Hu, Jing; Huang, Keqiang

    2017-02-01

    Tongue squamous cell carcinoma (TSCC) is one of the most severe types of cancer with poor outcomes. Cisplatin is used widely to treat cancer cells, but many patients develop acquired drug resistance. The receptor for advanced glycation end products (RAGE) is expressed widely in TSCC and associated with drug-induced chemotherapy resistance. However, the effect of RAGE and cisplatin on Tca-8113 cells remains unknown. We assayed the combined use of RAGE blockade and cisplatin effect on Tca-8113 cells' viability by MTT and apoptosis rate of Tca-8113 cells on RAGE blockade+cisplatin treatment; cisplatin alone; or RAGE blockade alone by flow cytometry. We observed the expressions of autophagy-related proteins beclin1, LC3II, p62; Wnt signaling-related proteins β-catenin, GSK3β, WNT5A, ROR-2; and apoptosis-related protein cleaved caspase-3, bcl-2-associated X proteins using western blot. We determined WNT5A and beclin1 expression on Tca-8113 cells by immunofluorescence. We further observed autophagy vacuoles by monodansylcadaverine staining. We found that RAGE blockade and cisplatin significantly decreased cell viability and increased the cell apoptosis rate compared with cisplatin alone. Furthermore, RAGE blockade suppressed the canonical Wnt pathway proteins β-catenin and GSK-3β, but upregulated noncanonical WNT5A and receptor ROR-2. We show that RAGE blockade suppressed the levels of autophagy-related protein LC3II/I, beclin1, accelerated degradation of autophagy for the increasing p62 expression, and increased cell apoptosis for the increasing expressions of cleaved caspase-3 and bcl-2-associated X proteins. We observed the location of WNT5A and beclin1 expressions on cells by immunofluorescence and their trends were consistent with western blotting. Taken together, our findings suggested that RAGE blockade+cisplatin improved chemotherapeutic effects by reducing autophagy and regulating Wnt/β-catenin to suppress the progression of TSCC.

  8. Dietary intake of advanced glycation end products did not affect endothelial function and inflammation in healthy adults in a randomized controlled trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When food is heated to high temperatures, the characteristic “browning” generates advanced glycation end products (AGEs) that result from the reaction of reducing sugars with proteins. AGEs have been implicated in an increased risk for cardiovascular disease, diabetes, and other adverse aging-relate...

  9. Plasma Levels of Pentosidine, Carboxymethyl-Lysine, Soluble Receptor for Advanced Glycation End Products, and Metabolic Syndrome: The Metformin Effect

    PubMed Central

    Haddad, Mohamed; Knani, Ines; Bouzidi, Hsan; Berriche, Olfa; Hammami, Mohamed

    2016-01-01

    Metabolic syndrome (MetS) is considered one of the most important public health problems. Several and controversial studies showed that the role of advanced glycation end products (AGEs) and their receptor in the development of metabolic syndrome and therapeutic pathways is still unsolved. We have investigated whether plasma pentosidine, carboxymethyl-lysine (CML), and soluble receptor for advanced glycation end products (sRAGE) levels were increased in patients with MetS and the effect of metformin in plasma levels of pentosidine, CML, and sRAGE. 80 control subjects and 86 patients were included in this study. Pentosidine, CML, and sRAGE were measured in plasma by enzyme-linked immunosorbent assay (ELISA). Plasma pentosidine, CML, and sRAGE levels were significantly increased in patients compared to control subjects (P < 0.001, P < 0.001, and P = 0.014, resp.). Plasma levels of pentosidine were significantly decreased in patients who received metformin compared to untreated patients (P = 0.01). However, there was no significant difference between patients treated with metformin and untreated patients in plasma CML levels. Plasma levels of sRAGE were significantly increased in patients who received metformin and ACE inhibitors (P < 0.001 and P = 0.002, resp.). However, in a multiple stepwise regression analysis, pentosidine, sRAGE, and drugs treatments were not independently associated. Patients with metabolic syndrome showed increased levels of AGEs such as pentosidine and CML. Metformin treatment showed a decreased level of pentosidine but not of CML. Therapeutic pathways of AGEs development should be taken into account and further experimental and in vitro studies merit for advanced research. PMID:27829696

  10. Kinetics of advanced glycation end products formation on bovine serum albumin with various reducing sugars and dicarbonyl compounds in equimolar ratios.

    PubMed

    Luers, Lars; Rysiewski, Karolina; Dumpitak, Christian; Birkmann, Eva

    2012-04-01

    Reducing sugars and reactive dicarbonyl compounds play a major role in glycation of proteins in vivo. Glycation of proteins is the first step in of a nonenzymatic reaction, resulting in advanced glycation end products (AGEs). AGEs can inactivate proteins or modify their biological activities. Therefore, it is important to understand the mechanism of AGE formation. Here, we systematically analyzed the kinetics of AGE formation in vitro by fluorescence and absorption measurements utilizing a microplate reader system and bovine serum albumin (BSA) as a model protein. Comparing different concentrations of BSA, we applied various reducing sugars and reactive dicarbonyl compounds as AGE-inducing agents at different concentrations. In summary, this experimental setup enabled us to measure the kinetics of AGE formation in an efficient and defined way.

  11. Blockade of receptor for advanced glycation end products protects against systolic overload-induced heart failure after transverse aortic constriction in mice.

    PubMed

    Liu, Yu; Yu, Manli; Zhang, Zhigang; Yu, Yunhua; Chen, Qi; Zhang, Wei; Zhao, Xianxian

    2016-11-15

    Heart failure is the consequence of sustained, abnormal neurohormonal and mechanical stress and remains a leading cause of death worldwide. The aim of this work was to identify whether blockade of receptor for advanced glycation end products (RAGE) protected against systolic overload-induced heart failure and investigate the possible underlying mechanism. It was found that RAGE mRNA and protein expression was up-regulated in cardiac tissues from mice subjected to pressure overload by transverse aortic constriction (TAC). Importantly, inhibition of RAGE by treatment with soluble RAGE (sRAGE) or FPS-ZM1 (a high-affinity RAGE-specific inhibitor) for 8 weeks attenuated cardiac remodeling (including cardiac hypertrophy and fibrosis), and dysfunction in mice exposed to TAC. Furthermore, treatment of TAC mice with sRAGE or FPS-ZM1 enhanced phosphorylation of AMPK and reduced phosphorylation of mTOR and protein expression of NFκB p65 in cardiac tissues. In addition, treatment of TAC mice with sRAGE or FPS-ZM1 abated oxidative stress, attenuated endoplasmic reticulum stress, and suppressed inflammation in cardiac tissues. These data demonstrated the benefits of blocking RAGE on the progression of systolic overload-induced heart failure in mice, which was possibly through modulating AMPK/mTOR and NFκB pathways.

  12. Isolation and characterization of a new advanced glycation endproduct of dehydroascorbic acid and lysine.

    PubMed

    Argirov, Ognyan K; Lin, Bin; Olesen, Paul; Ortwerth, Beryl J

    2003-03-17

    Proteins are subject of posttranslational modification by sugars and their degradation products in vivo. The process is often referred as glycation. L-Dehydroascorbic acid (DHA), an oxidation product of L-ascorbic acid (vitamin C), is known as a potent glycation agent. A new product of modification of lysine epsilon -amino group by DHA was discovered as a result of the interaction between Boc-Lys and dehydroascorbic acid. The chromatographic and spectral analyses revealed that the structure of the product was 1-(5-ammonio-5-carboxypentyl)-3-oxido-4-(hydroxymethyl)pyridinium. The same compound was isolated from DHA modified calf lens protein after hydrolysis and chromatographic separation. The study confirmed that L-erythrulose is an important intermediate of modification of proteins by DHA. The structure of the reported product and in vitro experiments suggested that L-erythrulose could further transform to L-threose, L-erythrose and glycolaldehyde under conditions similar to physiological. The present study revealed that the modification of epsilon -amino groups of lysine residues by DHA is a complex process and could involve a number of reactive carbonyl species.

  13. The receptor for advanced glycation end products promotes bacterial growth at distant body sites in Staphylococcus aureus skin infection.

    PubMed

    Achouiti, Ahmed; Van't Veer, Cornelis; de Vos, Alex F; van der Poll, Tom

    2015-09-01

    The receptor for advanced glycation endproducts (RAGE) has been implicated in the regulation of skin inflammation. We here sought to study the role of RAGE in host defense during skin infection caused by Staphylococcus (S.) aureus, the most common pathogen in this condition. Wild-type (Wt) and RAGE deficient (rage(-/-)) mice were infected subcutaneously with S. aureus and bacterial loads and local inflammation were quantified at regular intervals up to 8 days after infection. While bacterial burdens were similar in both mouse strains at the primary site of infection, rage(-/-) mice had lower bacterial counts in lungs and liver. Skin cytokine and chemokine levels did not differ between groups. In accordance with the skin model, direct intravenous infection with S. aureus was associated with lower bacterial loads in lungs and liver of rage(-/-) mice. Together these data suggest that RAGE does not impact local host defense during S. aureus skin infection, but facilitates bacterial growth at distant body sites.

  14. Cell signaling and receptors in toxicity of advanced glycation end products (AGEs): α-dicarbonyls, radicals, oxidative stress and antioxidants.

    PubMed

    Kovacic, Peter; Somanathan, Ratnasamy

    2011-10-01

    Considerable attention has been paid to the toxicity of advanced glycation end products (AGEs), including relation to various illnesses. AGEs, generated nonenzymatically from carbohydrates and proteins, comprises large numbers of simple and more complicated compounds. Many reports deal with a role for receptors (RAGE) and cell signaling, including illnesses and aging. Reactive oxygen species appear to participate in signaling. RAGE include angiotensin II type 1 receptors. Many signaling pathways are involved, such as kinases, p38, p21, TGF-β, NF-κβ, TNF-α, JNK and STAT. A recent review puts focus on α-dicarbonyl metabolites, formed by carbohydrate oxidation, and imine derivatives from protein condensation, as a source via electron transfer (ET) of ROS and oxidative stress (OS). The toxic species have been related to illnesses and aging. Antioxidants alleviate the adverse effects.

  15. Current perspectives on the health risks associated with the consumption of advanced glycation end products: recommendations for dietary management

    PubMed Central

    Palimeri, Sotiria; Palioura, Eleni; Diamanti-Kandarakis, Evanthia

    2015-01-01

    Advanced glycation end products (AGEs) constitute a complex group of compounds produced endogenously during the aging process and under conditions of hyperglycemia and oxidative stress. AGEs also have an emerging exogenous origin. Cigarette smoke and diet are the two main exogenous sources of AGEs (glycotoxins). Modern Western diets are rich in AGEs which have been implicated in the pathogenesis of several metabolic and degenerative disorders. Accumulating evidence underlies the beneficial effect of the dietary restriction of AGEs not only in animal studies but also in patients with diabetic complications and metabolic diseases. This article reviews the evidence linking dietary glycotoxins to several disorders from diabetic complications and renal failure to liver dysfunction, female reproduction, eye and cognitive disorders as well as cancer. Furthermore, strategies for AGE reduction are discussed with a focus on dietary modification. PMID:26366100

  16. Advanced glycation end products, carotid atherosclerosis, and circulating endothelial progenitor cells in patients with end-stage renal disease.

    PubMed

    Ueno, Hiroki; Koyama, Hidenori; Fukumoto, Shinya; Tanaka, Shinji; Shoji, Takuhito; Shoji, Tetsuo; Emoto, Masanori; Tahara, Hideki; Inaba, Masaaki; Kakiya, Ryusuke; Tabata, Tsutomu; Miyata, Toshio; Nishizawa, Yoshiki

    2011-04-01

    Numbers of endothelial progenitor cells (EPCs) have been shown to be decreased in subjects with end-stage renal disease (ESRD), the mechanism of which remained poorly understood. In this study, mutual association among circulating EPC levels, carotid atherosclerosis, serum pentosidine, and skin autofluorescence, a recently established noninvasive measure of advanced glycation end products accumulation, was examined in 212 ESRD subjects undergoing hemodialysis. Numbers of circulating EPCs were measured as CD34+ CD133+ CD45(low) VEGFR2+ cells and progenitor cells as CD34+ CD133+ CD45(low) fraction by flow cytometry. Skin autofluorescence was assessed by the autofluorescence reader; and serum pentosidine, by enzyme-linked immunosorbent assay. Carotid atherosclerosis was determined as intimal-medial thickness (IMT) measured by ultrasound. Circulating EPCs were significantly and inversely correlated with skin autofluorescence in ESRD subjects (R = -0.216, P = .002), but not with serum pentosidine (R = -0.079, P = .25). Circulating EPCs tended to be inversely associated with IMT (R = -0.125, P = .069). Intimal-medial thickness was also tended to be correlated positively with skin autofluorescence (R = 0.133, P = .054) and significantly with serum pentosidine (R = 0.159, P = .019). Stepwise multiple regression analyses reveal that skin autofluorescence, but not serum pentosidine and IMT, was independently associated with low circulating EPCs. Of note, skin autofluorescence was also inversely and independently associated with circulating progenitor cells. Thus, tissue accumulated, but not circulating, advanced glycation end products may be a determinant of a decrease in circulating EPCs in ESRD subjects.

  17. The receptor for advanced glycation end products impairs collateral formation in both diabetic and non-diabetic mice.

    PubMed

    Hansen, Laura M; Gupta, Divya; Joseph, Giji; Weiss, Daiana; Taylor, W Robert

    2017-01-01

    Diabetics often have poor perfusion in their limbs as a result of peripheral artery disease and an impaired ability to generate collateral vessels. The receptor for advanced glycation end products (RAGE) is one protein that is thought to play a detrimental role in collateral development in diabetics due to increased levels of advanced glycation end products (AGE), one of its ligands, in diabetes. Thus, the aim of this study was to investigate the role of RAGE in both diabetic and non-diabetic settings in a model of collateral formation in mice. Streptozotocin was used to induce diabetes in both wild type and RAGE knockout mice. Increased levels of the AGE, N(ɛ)-(carboxymethyl) lysine (CML), were confirmed via an ELISA. A hindlimb ischemia model, in which the femoral artery is ligated, was used to drive collateral growth and reperfusion was assessed using laser Doppler perfusion imaging and histological analysis of vessels in the muscle. Both of these measurements showed impaired collateral growth in diabetic compared with wild-type mice as well as improved collateral growth in both diabetic and non-diabetic RAGE knockout mice when compared their wild-type counterparts. Distance on a freely accessed running wheel, used as a measure of perfusion recovery, showed that wild-type diabetic mice had functionally impaired recovery compared with their wild-type counterparts. Immunohistochemistry and immunoblotting showed that HMGB-1 (high-mobility group box 1), another RAGE ligand, was increased in the ischemic leg compared with the non-ischemic leg in all mice. This increase in HMGB-1 may explain improvement in animals lacking RAGE and its subsequent signaling. In conclusion, this study shows that RAGE impairs collateral growth in a diabetic setting and also in a non-diabetic setting. This demonstrates the importance of RAGE and alternate RAGE ligands in the setting of collateral vessel growth.

  18. Advanced Glycation End Products Modulate Structure and Drug Binding Properties of Albumin.

    PubMed

    Awasthi, Saurabh; Murugan, N Arul; Saraswathi, N T

    2015-09-08

    The extraordinary ligand binding properties of albumin makes it a key player in the pharmacokinetics and pharmacodynamics of many vital drugs. Albumin is highly susceptible for nonenzymatic glycation mediated structural modifications, and there is a need to determine structural and functional impact of specific AGEs modifications. The present study was aimed toward determining the AGE mediated structure and function changes, primarily looking into the effect on binding affinity of drugs in the two major drug binding sites of albumin. The impact of the two most predominant AGEs modifications, i.e., carboxyethyllysine (CEL) and argpyrimidine (Arg-P), was studied on the basis of the combination of in vitro and in silico experiments. In vitro studies were carried out by AGEs modification of bovine serum albumin (BSA) for the formation of Arg-P and CEL followed by drug interaction studies. In silico studies involved molecular dynamics (MD) simulations and docking studies for native and AGEs modified BSAs. In particular the side chain modification was specifically carried out for the residues in the drug binding sites, i.e., Arg-194, Arg-196, Arg-198, and Arg-217, and Lys-204 (site I) and Arg-409 and Lys-413 (site II). The equilibrated structures of native BSA (n-BSA) and glycated BSA (G-BSA) as obtained from MD were used for drug binding studies using molecular docking approach. It was evident from the results of both in vitro and in silico drug interaction studies that AGEs modification results in the reduced drug binding affinity for tolbutamide (TLB) and ibuprofen (IBP) in sites I and II. Moreover, the AGEs modification mediated conformational changes resulted in the shallow binding pockets with reduced accessibility for drugs.

  19. Angiogenesis impairment in diabetes: role of methylglyoxal-induced receptor for advanced glycation endproducts, autophagy and vascular endothelial growth factor receptor 2.

    PubMed

    Liu, Hongtao; Yu, Shujie; Zhang, Hua; Xu, Jian

    2012-01-01

    Diabetes impairs physiological angiogenesis by molecular mechanisms that are not fully understood. Methylglyoxal (MGO), a metabolite of glycolysis, is increased in patients with diabetes. This study defined the role of MGO in angiogenesis impairment and tested the mechanism in diabetic animals. Endothelial cells and mouse aortas were subjected to Western blot analysis of vascular endothelial growth factor receptor 2 (VEGFR2) protein levels and angiogenesis evaluation by endothelial cell tube formation/migration and aortic ring assays. Incubation with MGO reduced VEGFR2 protein, but not mRNA, levels in a time and dose dependent manner. Genetic knockdown of the receptor for advanced glycation endproducts (RAGE) attenuated the reduction of VEGFR2. Overexpression of Glyoxalase 1, the enzyme that detoxifies MGO, reduced the MGO-protein adducts and prevented VEGFR2 reduction. The VEGFR2 reduction was associated with impaired angiogenesis. Suppression of autophagy either by inhibitors or siRNA, but not of the proteasome and caspase, normalized both the VEGFR2 protein levels and angiogenesis. Conversely, induction of autophagy either by rapamycin or overexpression of LC3 and Beclin-1 reduced VEGFR2 and angiogenesis. MGO increased endothelial LC3B and Beclin-1, markers of autophagy, which were accompanied by an increase of both autophagic flux (LC3 punctae) and co-immunoprecipitation of VEGFR2 with LC3. Pharmacological or genetic suppression of peroxynitrite (ONOO(-)) generation not only blocked the autophagy but also reversed the reduction of VEGFR2 and angiogenesis. Like MGO-treated aortas from normglycemic C57BL/6J mice, aortas from diabetic db/db and Akita mice presented reductions of angiogenesis or VEGFR2. Administration of either autophagy inhibitor ex vivo or superoxide scavenger in vivo abolished the reductions. Taken together, MGO reduces endothelial angiogenesis through RAGE-mediated, ONOO(-)dependent and autophagy-induced VEGFR2 degradation, which may represent

  20. Detection of an aging-related increase in advanced glycation end products in fast- and slow-twitch skeletal muscles in the rat.

    PubMed

    Ramamurthy, B; Larsson, L

    2013-06-01

    Glycation, a non-enzymatic addition of reducing sugars to ε-amino groups of proteins, is a post-translational modification that results in the formation of irreversible advanced glycation end products (AGEs). Ageing related decline in myofibrillar protein function is effected by a number of structural and functional modifications including glycation. Functional properties of skeletal muscles, such as maximum velocity of unloaded shortening, are known to be profoundly affected by ageing at the motor unit, cellular and tissue levels. However, the contribution of protein modifications to a decline in muscle function is not well understood. In this study we measured AGEs of intracellular and sarcolemmal proteins, using an anti-AGE antibody in soleus (SOL) and extensor digiotorum longus (EDL) muscles of male and female rats of five different age groups. Using a fluorescent secondary antibody to visualize AGEs in the confocal microscope, we found that myosin is glycated in both fiber types in all age groups; an ageing related increase in AGEs was observed in both intracellular and sarcolemmal regions in all age groups, with the exception of sarcolemma of SOL (unchanged) and EDL (reduced) in female rats; the greatest concentration of AGEs was found intracellularly in the SOL of the oldest age group (27-30) of females. While an ageing related decline in motor properties can be partially attributed to the observed increase in myofibrillar protein glycation, our results also indicate that intracellular and the less well studied sarcolemmal protein modification likely contribute to an aging-related decline in muscle function. Further studies are required to establish a link between the observed ageing related increase in glycation and muscle function at the motor unit, cellular and tissue levels.

  1. Advanced glycation end products as an upstream molecule triggers ROS-induced sFlt-1 production in extravillous trophoblasts: a novel bridge between oxidative stress and preeclampsia.

    PubMed

    Huang, Q T; Zhang, M; Zhong, M; Yu, Y H; Liang, W Z; Hang, L L; Gao, Y F; Huang, L P; Wang, Z J

    2013-12-01

    Although abnormal soluble fms-like tyrosine kinase-1 (sFlt-1) production is thought to be an important factor in the pathogenesis of pre-eclampsia, the mechanisms that regulate the production of sFlt-1 during pre-eclampsia are unclear. Accumulation of advanced glycation end products (AGEs) is prevalent in obesity, advanced maternal age, diabetes mellitus, and polycystic ovary syndrome. Alterations in the regulation and signaling of angiogenic pathways have been considered as a link between these conditions and pre-eclampsia. The purpose of this study was to explore the possible effects of AGEs on sFlt-1 secretion in extravillous trophoblasts (EVT). A EVT cell line (HRT-8/SVneo) was treated with various concentrations of AGEs-BSA. The mRNA expression of sFlt-1, vascular endothelial growth factor (VEGF), and placental growth factor (PlGF) in EVT were detected with real-time polymerase chain reaction. The secretion of sFlt-1, VEGF, and PlGF protein from EVT was measured with ELISA. The levels of intracellular reactive oxygen species (ROS) production were determined by DCFH-DA. Exposure of EVT to AGEs-BSA induced increased intracellular ROS generation and overexpression of sFlt-1 at mRNA and protein levels in a dose dependent manner. Anti-RAGE immunoglobulin G or apocynin (an inhibitors of NADPH oxidase) could decrease the intracellular ROS generation and subsequently suppressed the production of sFlt-1 at mRNA and protein levels. Our data suggested that AGEs may be a new class of important mediator in the regulation of angiogenic pathways of EVT. Accumulation of AGEs might contribute to the pathogenesis of preeclampsia by promoting sFlt-1 production through activation of RAGE/NADPH oxidase dependent pathway in EVT.

  2. Advanced glycation end products: possible link between metabolic syndrome and periodontal diseases.

    PubMed

    Pietropaoli, D; Monaco, A; Del Pinto, R; Cifone, M G; Marzo, G; Giannoni, M

    2012-01-01

    On a planetary scale, Metabolic Syndrome (MetS)is the third cause of inability after malnutrition and nicotinism, even higher than water shortage and sedentariness. In the USA, the prevalence is estimated at over 25 percent of the population; in Italy, it involves approximately 25 percent of men and even 27 percent of women. These are very high figures, corresponding to approximately 14 million affected individuals. The prevalence is alarming and must not be underestimated, particularly in the dental field, where more than one patient out of four sitting in a dentist chair is affected. The etiology of periodontal disease has not yet been clarified, and recently the idea to consider it as a multifactor pathology has been developed. Cofactors such as the formation of free radicals of oxygen (ROS), oxidative stress, lipid peroxidation, and formation of glycation end-products (AGEs) probably play an important role in the onset of periodontal disease. The AGEs are compounds physiologically produced by the cells. However, they accumulate and cause pro-inflammatory conditions, when the cellular clearance fails, or in hyperglycemic and oxidative states. All these conditions can be clinically summarized as Metabolic Syndrome. The purpose of this literature review is to establish a relationship between two pathologies with very high prevalence: Metabolic Syndrome and Periodontal Disorder. The literature seems to have clarified that MetS involves a pro-oxidation status, which induces AGE formation. AGEs play a very important role in the course and severity of periodontal diseases.

  3. Basic and Clinical Research Against Advanced Glycation End Products (AGEs): New Compounds to Tackle Cardiovascular Disease and Diabetic Complications.

    PubMed

    Nenna, Antonio; Spadaccio, Cristiano; Lusini, Mario; Ulianich, Luca; Chello, Massimo; Nappi, Francesco

    2015-01-01

    Diabetes is a major risk factor for cardiovascular disease, and recent advances in research indicate that a detailed understanding of the pathophysiology of its effects is mandatory to reduce diabetes-related mortality and morbidity. Advanced Glycation End Products (AGEs) play a central role in the genesis and progression of complications of both type 1 and type 2 diabetes mellitus, and have been found to be important even in non-diabetic patients as a marker of cardiovascular disease. AGEs have a profound impact on patient's prognosis regardless of the glycemic control, and therefore pharmacologic approaches against AGEs accumulation have been proposed over the years to treat cardiovascular diseases, parallel to a more detailed understanding of AGEs pathophysiology. Compounds with anti-AGEs effects are currently under investigation in both pre-clinical and clinical scenarios, and many of the drugs previously used to treat specific diseases have been found to have AGE-inhibitory effects. Some products are still in "bench evaluation", whereas others have been already investigated in clinical trials with conflicting evidences. This review aims at summarizing the mechanisms of AGEs formation and accumulation, and the most relevant issues in pre-clinical and clinical experiences in anti-AGEs treatment in cardiovascular research.

  4. Receptor for advanced glycation end products and neuronal deficit in the fatal brain edema of diabetic ketoacidosis.

    PubMed

    Hoffman, William H; Artlett, Carol M; Zhang, Weixian; Kreipke, Christian W; Passmore, Gregory G; Rafols, Jose A; Sima, Anders A F

    2008-10-31

    Radiologic and neuropsychologic studies suggest that diabetes mellitus causes structural changes in the brain and adversely effects cognitive development. Experimental animal models of type 1 diabetes mellitus (T1DM) have advanced these findings by demonstrating duration-related neuronal and cognitive deficits in T1DM BB/Wor rats. We studied the expression of receptor for advanced glycation end products (RAGE) and neuronal densities in the brains of two patients who died as the result of clinical brain edema(BE)that developed during the treatment of severe diabetic ketoacidosis (DKA). RAGE was markedly and diffusely expressed in blood vessels, neurons, and the choroid plexus and co-localized with glial fibrillary acidic protein (GFAP) in astrocytes. Significant neuronal loss was seen in the hippocampus and frontal cortex. Astrocytosis was present and white matter was atrophied in both cases when compared to age-matched controls. Our data supports that a neuroinflammatory response occurs in the BE associated with DKA, and that even after a relatively short duration of poorly controlled T1DM, the pathogenesis of primary diabetic encephalopathy can be initiated.

  5. Anti-Advanced Glycation End-product and Free Radical Scavenging Activity of Plants from the Yucatecan Flora

    PubMed Central

    Dzib-Guerra, Wendy del C.; Escalante-Erosa, Fabiola; García-Sosa, Karlina; Derbré, Séverine; Blanchard, Patricia; Richomme, Pascal; Peña-Rodríguez, Luis M.

    2016-01-01

    Background: Formation and accumulation of advanced glycation end-products (AGE) is recognized as a major pathogenic process in diabetic complications, atherosclerosis and cardiovascular diseases. In addition, reactive oxygen species and free radicals have also been reported to participate in AGE formation and in cell damage. Natural products with antioxidant and antiAGE activity have great therapeutic potential in the treatment of diabetes, hypertension and related complications. Objective: to test ethanolic extracts and aqueous-traditional preparations of plants used to treat diabetes, hypertension and obesity in Yucatecan traditional medicine for their anti-AGE and free radical scavenging activities. Materials and Methods: ethanolic extracts of leaves, stems and roots of nine medicinal plants, together with their traditional preparations, were prepared and tested for their anti-AGE and antioxidant activities using the inhibition of advanced glycation end products and DPPH radical scavenging assays, respectively. Results: the root extract of C. fistula (IC50= 0.1 mg/mL) and the leaf extract of P. auritum (IC50= 0.35 mg/mL) presented significant activity against vesperlysine and pentosidine-like AGE. Although none of the aqueous traditional preparations showed significant activity in the anti-AGE assay, both the traditional preparations and the ethanolic extracts of E. tinifolia, M. zapota, O. campechianum and P. auritum showed significant activity in the DPPH reduction assay. Conclusions: the results suggest that the metabolites responsible for the detected radical-scavenging activity are different to those involved in inhibiting AGE formation; however, the extracts with antioxidant activity may contain other metabolites which are able to prevent AGE formation through a different mechanism. SUMMARY Ethanolic extracts from nine plants used to treat diabetes, hypertension and obesity in Yucatecan traditional medicine were tested for their anti-AGE and free radical

  6. Dimerumic acid attenuates receptor for advanced glycation endproducts signal to inhibit inflammation and diabetes mediated by Nrf2 activation and promotes methylglyoxal metabolism into d-lactic acid.

    PubMed

    Lee, Bao-Hong; Hsu, Wei-Hsuan; Hsu, Ya-Wen; Pan, Tzu-Ming

    2013-07-01

    This study was designed to evaluate the effects of dimerumic acid (DMA) on receptor for advanced glycation endproducts (RAGE) signal activation and THP-1 monocyte inflammation treated with S100b, a specific ligand of RAGE. We found that DMA inhibited inflammatory cytokine production via upregulation of nuclear factor-erythroid 2-related factor 2 (Nrf2) and alleviated oxidative stress through attenuation of p47phox translocation to the membrane of S100b-treated THP-1 monocytes. We found that DMA activated Nrf2 mediated by the p38 kinase pathway in THP-1 monocytes. However, anti-inflammatory activity of DMA was attenuated by Nrf2 siRNA treatment. In an animal model, methylglyoxal (MG; 200mg/kg bw) was chosen to induce diabetes in Balb/C mice (6 weeks) in this work. The in vivo verification of anti-inflammation in peripheral blood mononuclear cells by DMA treatment was confirmed by tumor necrosis factor-α and interleukin-1β measurements. Oral glucose tolerance test, insulin tolerance test, hyperinsulinemia, and hyperglycemia were improved in MG-treated mice by DMA treatment and these effects were greater than those of silymarin and N-acetylcysteine. Furthermore, DMA increased hepatic glyoxalase mRNA and glutathione mediated by Nrf2 activation to metabolize MG into d-lactic acid, thereby reducing serum and hepatic AGE levels and suppressing inflammatory factor generation in MG-treated mice. However, DMA did not exert the antiglycation activity in MG-bovine serum albumin incubation. Taken together, the results indicate that DMA is a novel antioxidant and Nrf2 activator that lowers AGE levels and may prove to be an effective treatment for diabetes.

  7. Pravastatin inhibits advanced glycation end products (AGEs)-induced proximal tubular cell apoptosis and injury by reducing receptor for AGEs (RAGE) level.

    PubMed

    Ishibashi, Yuji; Yamagishi, Sho-ichi; Matsui, Takanori; Ohta, Keisuke; Tanoue, Ryuichiro; Takeuchi, Masayoshi; Ueda, Seiji; Nakamura, Kei-ichiro; Okuda, Seiya

    2012-08-01

    Advanced glycation end products (AGEs) and their receptor (RAGE) axis play a role in diabetic nephropathy. Statins have been shown to ameliorate renal function and reduce proteinuria in patients with chronic kidney disease. However, the effects of statin on AGEs-induced tubular cell damage remain unknown. We examined here whether and how pravastatin could block the AGEs-RAGE-elicited tubular cell injury in vitro. Gene expression level was evaluated by real-time reverse-transcription polymerase chain reactions. Reactive oxygen species (ROS) generation was measured with dihydroethidium staining. Apoptosis was analyzed in an enzyme-linked immunosorbent assay. Asymmetric dimethylarginine (ADMA) expression was evaluated by immunostaining. Pravastatin dose-dependently inhibited the AGEs-induced up-regulation of RAGE mRNA level, ROS generation and apoptosis in human renal proximal tubular cells. Further, AGEs decreased mRNA level of dimethylarginine dimethylaminohydrolase-2, an enzyme that mainly degrades asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase and subsequently increased ADMA generation in tubular cells, both of which were also prevented by pravastatin. Geranylgeranyl pyrophosphate (GGPP) treatment blocked all of the effects of pravastatin on tubular cells. We found that rosuvastatin also significantly blocked the AGEs-induced increase in RAGE mRNA level and ROS generation, both of which were prevented by GGPP. Our present study suggests that pravastatin could inhibit the AGEs-induced apoptosis and ADMA generation in tubular cells by suppressing RAGE expression probably via inhibition of GGPP synthesis. Pravastatin may exert beneficial effects on tubular damage in diabetic nephropathy by blocking the AGEs-RAGE axis.

  8. Selective inhibition by grape seed proanthocyanidin extracts of cell adhesion molecule expression induced by advanced glycation end products in endothelial cells.

    PubMed

    Zhang, Feng-Lei; Gao, Hai-Qing; Wu, Jian-Min; Ma, Ya-Bing; You, Bei-An; Li, Bao-Ying; Xuan, Jun-Hua

    2006-08-01

    The interaction of advanced glycation end products (AGE) with their cell surface receptors for AGEs (RAGE) has been causally implicated in the pathogenesis of diabetic vascular complications and has been shown to stimulate cell adhesion molecule expression in endothelial cells via induction of reactive oxygen species (ROS). Alternatively, grape seed proanthocyanidin extracts (GSPE), which are naturally occurring polyphenolic compounds, have been reported to possess potent radical scavenging and antioxidant properties and to display significant cardiovascular protective action. In this study, we investigated whether GSPE could inhibit AGE-induced cell adhesion molecule expression through interference with ROS generations in human umbilical vein endothelial cells. AGE-modified bovine serum albumin (AGE-BSA) was prepared by incubating BSA with a high concentration of glucose. Stimulation of cultured human umbilical vein endothelial cells with 200 microg/mL of AGE-BSA significantly enhanced intracellular ROS formation and subsequently upregulated the expression of vascular cell adhesion molecule-1 (VCAM) and intercellular adhesion molecule-1 (ICAM-1), whereas both unmodified BSA and GSPE alone were without effect. However, preincubation of different concentrations of GSPE markedly downregulated AGE-BSA-induced VCAM-1 expression at the surface protein and mRNA level in a concentration-dependent manner, but the increased ICAM-1 expression was not affected by GSPE treatment. Meanwhile, the inhibition by GSPE of intracellular ROS generation was also observed at defined time periods. These results demonstrate that GSPE can inhibit the enhanced VCAM-1 expression but not ICAM-1 in AGE-exposed endothelial cells by suppressing ROS generation. Hence, GSPE may have therapeutic potential in the prevention and treatment of vascular complications in patients with diabetes.

  9. Bazedoxifene Ameliorates Homocysteine-Induced Apoptosis and Accumulation of Advanced Glycation End Products by Reducing Oxidative Stress in MC3T3-E1 Cells.

    PubMed

    Kanazawa, Ippei; Tomita, Tsutomu; Miyazaki, Shun; Ozawa, Eiji; Yamamoto, Luis A; Sugimoto, Toshitsugu

    2017-03-01

    Elevated plasma homocysteine (Hcy) level increases the risk of osteoporotic fracture by deteriorating bone quality. However, little is known about the effects of Hcy on osteoblast and collagen cross-links. This study aimed to investigate whether Hcy induces apoptosis of osteoblastic MC3T3-E1 cells as well as affects enzymatic and nonenzymatic collagen cross-links and to determine the effects of bazedoxifene, a selective estrogen receptor modulator, on the Hcy-induced apoptosis and deterioration of collagen cross-links in the cells. Hcy treatments (300 μM, 3 mM, and 10 mM) increased intracellular reactive oxygen species (ROS) production in a dose-dependent manner. Propidium iodide staining showed that 3 and 10 mM Hcy induced apoptosis of MC3T3-E1 cells. Moreover, the activities of caspases-8, 9, and 3 were increased by 3 mM Hcy. The detrimental effects of 3 mM Hcy on apoptosis and ROS production were partly reversed by bazedoxifene and 17β estradiol. In addition, real-time PCR, immunostaining and Western blot showed that 300 μM Hcy decreased the expression of lysyl oxidase (Lox). Furthermore, 300 μM Hcy increased extracellular accumulation of pentosidine, an advanced glycation end product. Treatment with bazedoxifene ameliorated Hcy-induced suppression of Lox expression and increase in pentosidine accumulation. These findings suggest that high-dose Hcy induces apoptosis of osteoblasts by increasing oxidative stress, and low-dose Hcy decreases enzymatic collagen cross-links and increases pentosidine accumulation, resulting in the deterioration of bone quality. Bazedoxifene treatment effectively prevents the Hcy-induced detrimental reactions of osteoblasts. Thus, bazedoxifene may be a potent therapeutic drug for preventing Hcy-induced bone fragility.

  10. Nifedipine inhibits advanced glycation end products (AGEs) and their receptor (RAGE) interaction-mediated proximal tubular cell injury via peroxisome proliferator-activated receptor-gamma activation

    SciTech Connect

    Matsui, Takanori; Yamagishi, Sho-ichi; Takeuchi, Masayoshi; Ueda, Seiji; Fukami, Kei; Okuda, Seiya

    2010-07-23

    Research highlights: {yields} Nifedipine inhibited the AGE-induced up-regulation of RAGE mRNA levels in tubular cells, which was prevented by GW9662, an inhibitor of peroxisome proliferator-activated receptor-{gamma}. {yields} GW9662 treatment alone increased RAGE mRNA levels in tubular cells. {yields} Nifedipine inhibited the AGE-induced reactive oxygen species generation, NF-{kappa}B activation and increases in intercellular adhesion molecule-1 and transforming growth factor-{beta} gene expression in tubular cells, all of which were blocked by GW9662. -- Abstract: There is a growing body of evidence that advanced glycation end products (AGEs) and their receptor (RAGE) interaction evokes oxidative stress generation and subsequently elicits inflammatory and fibrogenic reactions, thereby contributing to the development and progression of diabetic nephropathy. We have previously found that nifedipine, a calcium-channel blocker (CCB), inhibits the AGE-induced mesangial cell damage in vitro. However, effects of nifedipine on proximal tubular cell injury remain unknown. We examined here whether and how nifedipine blocked the AGE-induced tubular cell damage. Nifedipine, but not amlodipine, a control CCB, inhibited the AGE-induced up-regulation of RAGE mRNA levels in tubular cells, which was prevented by the simultaneous treatment of GW9662, an inhibitor of peroxisome proliferator-activated receptor-{gamma} (PPAR{gamma}). GW9662 treatment alone was found to increase RAGE mRNA levels in tubular cells. Further, nifedipine inhibited the AGE-induced reactive oxygen species generation, NF-{kappa}B activation and increases in intercellular adhesion molecule-1 and transforming growth factor-beta gene expression in tubular cells, all of which were blocked by GW9662. Our present study provides a unique beneficial aspect of nifedipine on diabetic nephropathy; it could work as an anti-oxidative and anti-inflammatory agent against AGEs in tubular cells by suppressing RAGE expression

  11. Modeling the interaction between quinolinate and the receptor for advanced glycation end products (RAGE): relevance for early neuropathological processes.

    PubMed

    Serratos, Iris N; Castellanos, Pilar; Pastor, Nina; Millán-Pacheco, César; Rembao, Daniel; Pérez-Montfort, Ruy; Cabrera, Nallely; Reyes-Espinosa, Francisco; Díaz-Garrido, Paulina; López-Macay, Ambar; Martínez-Flores, Karina; López-Reyes, Alberto; Sánchez-García, Aurora; Cuevas, Elvis; Santamaria, Abel

    2015-01-01

    The receptor for advanced glycation end products (RAGE) is a pattern-recognition receptor involved in neurodegenerative and inflammatory disorders. RAGE induces cellular signaling upon binding to a variety of ligands. Evidence suggests that RAGE up-regulation is involved in quinolinate (QUIN)-induced toxicity. We investigated the QUIN-induced toxic events associated with early noxious responses, which might be linked to signaling cascades leading to cell death. The extent of early cellular damage caused by this receptor in the rat striatum was characterized by image processing methods. To document the direct interaction between QUIN and RAGE, we determined the binding constant (Kb) of RAGE (VC1 domain) with QUIN through a fluorescence assay. We modeled possible binding sites of QUIN to the VC1 domain for both rat and human RAGE. QUIN was found to bind at multiple sites to the VC1 dimer, each leading to particular mechanistic scenarios for the signaling evoked by QUIN binding, some of which directly alter RAGE oligomerization. This work contributes to the understanding of the phenomenon of RAGE-QUIN recognition, leading to the modulation of RAGE function.

  12. Phytochemicals from Camellia nitidissima Chi inhibited the formation of advanced glycation end-products by scavenging methylglyoxal.

    PubMed

    Wang, Weixin; Liu, Haiyan; Wang, Zhennan; Qi, Jing; Yuan, Shengtao; Zhang, Weijie; Chen, Hongjuan; Finley, John W; Gu, Liwei; Jia, Ai-Qun

    2016-08-15

    The objective of this study was to investigate the inhibitory effects of Camellia nitidissima Chi (CNC) on the advanced glycation end-product (AGE) formation. CNC was extracted with ethanol and further separated into dichloromethane, ethyl acetate, n-butanol, and water soluble fractions. Ethyl acetate fraction had the highest total phenolic and quercetin content compared with other fractions. Sixteen phenolic compounds were identified using HPLC Triple TOF MS/MS. Bovine serum albumin (BSA)-glucose assay showed that dichloromethane and ethyl acetate fraction inhibited AGE formation by 88.1% and 87.5% at 2.5mg/mL. BSA-methylglyoxal assay showed that ethyl acetate fraction inhibited 54.1% AGE formation while dichloromethane fraction inhibited 28.1%. Over 96.0% of methylglyoxal was scavenged by different fractions within 12h. Both mono- and di-methylglyoxal quercetin adducts were identified after incubating quercetin with methylglyoxal using HPLC-ESI-MS(n). The results in this study suggest that CNC extracts inhibited AGEs formation in part through scavenging methylglyoxal by phenolic compounds.

  13. Genotoxicity of Advanced Glycation End Products: Involvement of Oxidative Stress and of Angiotensin II Type 1 Receptors

    NASA Astrophysics Data System (ADS)

    Schupp, Nicole; Schinzel, Reinhard; Heidland, August; Stopper, Helga

    2005-06-01

    In patients with chronic renal failure, cancer incidence is increased. This may be related to an elevated level of genomic damage, which has been demonstrated by micronuclei formation as well as by comet assay analysis. Advanced glycation end products (AGEs) are markedly elevated in renal failure. In the comet assay, the model AGEs methylglyoxal- and carboxy(methyl)lysine-modified bovine serum albumin (BSA) induced significant DNA damage in colon, kidney, and liver cells. The addition of antioxidants prevented AGE-induced DNA damage, suggesting enhanced formation of reactive oxygen species (ROS). The coincubation with dimethylfumarate (DMF), an inhibitor of NF-κB translocation, reduced the genotoxic effect, thereby underscoring the key role of NF-κB in this process. One of the genes induced by NF-κB is angiotensinogen. The ensuing proteolytic activity yields angiotensin II, which evokes oxidative stress as well as proinflammatory responses. A modulator of the renin-angiotensin system (RAS), the angiotensin II (Ang II) receptor 1 antagonist, candesartan, yielded a reduction of the AGE-induced DNA damage, connecting the two signal pathways, RAS and AGE signaling. We were able to identify important participants in AGE-induced DNA damage: ROS, NF-κB, and Ang II, as well as modulators to prevent this DNA damage: antioxidants, DMF, and AT1 antagonists.

  14. Genotoxicity and immunogenicity of DNA-advanced glycation end products formed by methylglyoxal and lysine in presence of Cu2+.

    PubMed

    Ahmad, Saheem; Moinuddin; Dixit, Kiran; Shahab, Uzma; Alam, Khursheed; Ali, Asif

    2011-04-15

    The highly reactive electrophile, methylglyoxal (MG), a break down product of carbohydrates, is a major environmental mutagen having potential genotoxic effects. Previous studies have suggested the reaction of MG with free amino groups of proteins forming advanced glycation end products (AGEs). This results in the generation of free radicals which play an important role in pathophysiology of aging and diabetic complications. MG also reacts with free amino group of nucleic acids resulting in the formation of DNA-AGEs. While the formation of nucleoside AGEs has been demonstrated previously, no extensive studies have been performed to assess the genotoxicity and immunogenicity of DNA-AGEs. In this study we report both the genotoxicity and immunogenicity of AGEs formed by MG-Lys-Cu(2+) system. Genotoxicity of the experimentally generated AGEs was confirmed by comet-assay. Spectroscopical analysis and melting temperature studies suggest structural perturbations in the DNA as a result of modification. This might be due to generation of single-stranded regions and destabilization of hydrogen bonds. Immunogenicity of native and MG-Lys-Cu(2+)-DNA was probed in female rabbits. The modified DNA was highly immunogenic eliciting high titre immunogen specific antibodies, while the unmodified form was almost non-immunogenic. The results show structural perturbations in MG-Lys-Cu(2+)-DNA generating new epitopes that render the molecule immunogenic.

  15. Advanced glycation end products as biomarkers and gerontotoxins - A basis to explore methylglyoxal-lowering agents for Alzheimer's disease?

    PubMed

    Krautwald, Martina; Münch, Gerald

    2010-10-01

    Alzheimer's disease (AD) is the most common dementing disorder of late life. Although there might be various different triggering events in the early stages of the disease, they seem to converge on a few characteristic final pathways in the late stages, characterized by inflammation and neurodegeneration. In this review, we put forward the hypothesis that advanced glycation end products (AGEs) and their precursors, including methylglyoxal, are both biomarkers and causative agents ("gerontotoxins") characteristic for this disorder. Accumulation of AGEs is a normal feature of aging, but is accelerated in AD, where AGEs can be detected in amyloid plaques and neurofibrillary tangles. AGE modification may explain many of the neuropathological and biochemical features of AD such as extensive protein cross-linking, inflammation, oxidative stress and neuronal cell death. We suggest that methylglyoxal is one of the major carbonyl species responsible for the formation of AGEs. We propose that one promising pharmacological approach to prevent the formation of AGEs would be to lower the methylglyoxal concentration. This can be achieved, for example, by decreasing the concentration of methylglyoxal precursors such as d-glyceraldehyde-3-phosphate by allowing a higher flux through the pentose phosphate pathway or by increasing methylglyoxal detoxification through the glyoxalase system. Alternatively, methylglyoxal could be scavenged by various types of carbonyl scavengers.

  16. Glucagon-like peptide-1 protects hippocampal neurons against advanced glycation end product-induced tau hyperphosphorylation.

    PubMed

    Chen, S; An, F-M; Yin, L; Liu, A-R; Yin, D-K; Yao, W-B; Gao, X-D

    2014-01-03

    We have previously demonstrated that glucagon-like peptide-1 (GLP-1) receptor agonist ameliorated neurodegenerative changes in rat models of diabetes-related Alzheimer's disease (AD), and protected neurons from glucose toxicity in vitro. Herein, we investigated the effects of GLP-1 receptor mediates on cell toxicity and tau hyperphosphorylation induced by advanced glycation end products (AGEs), which are associated with glucose toxicity, and the molecular mechanism in PC12 cells and the primary hippocampal neurons. Our study demonstrated that the similar protection effects of GLP-1 existed in PC12 cells treated with glucose-bovine serum albumin (BSA) in hyperglycemic conditions or with glycoaldehyde-BSA alone. Additionally, glucose-BSA alone did not induce significant cytotoxicity in PC12 cells, but resulted in tau hyperphosphorylation in primary hippocampal neurons in 24h. And we found that GLP-1 could reduce cell tau phosphorylation induced by high glucose or glucose-BSA. Furthermore, our data in the present study suggested that GLP-1 regulated tau phosphorylation induced by AGEs through a signaling pathway involving glycogen synthase kinase 3β (GSK-3β), similarly to the GSK-3β inhibitor, lithium chloride. Our findings suggest that GLP-1 can protect neurons from diabetes-associated AGE insults in vitro, and provide new evidence for a potential therapeutic value of GLP-1 receptor agonist in the treatment of AD especially diabetes-related AD.

  17. Endogenous secretory receptor for advanced glycation end-products inhibits amyloid-β1-42 uptake into mouse brain.

    PubMed

    Sugihara, Takahiro; Munesue, Seiichi; Yamamoto, Yasuhiko; Sakurai, Shigeru; Akhter, Nasima; Kitamura, Yoji; Shiba, Kazuhiro; Watanabe, Takuo; Yonekura, Hideto; Hayashi, Yasuhiko; Hamada, Jun-Ichiro; Yamamoto, Hiroshi

    2012-01-01

    The cell-surface receptor for advanced glycation end-products (RAGE) has been implicated in the development of diabetic vascular complications and Alzheimer's disease. RAGE has been considered to be involved in amyloid-β1-42 (Aβ1-42) uptake into brain. In the present study, we demonstrate that endogenous secretory RAGE (esRAGE), a decoy form of RAGE generated by alternative RNA processing, is able to inhibit Aβ1-42 influx into mouse brain. Surface plasmon resonance and competitive binding assays revealed that human Aβ1-42 interacted with human esRAGE within the immunoglobulin V type region. We next examined the uptake and distribution of 125I-labeled human Aβ1-42 in various organs and body fluids of newly created mice overexpressing human esRAGE as well as RAGE-null and wild-type (WT) mice. The transition of the 125I-labeled Aβ1-42 from circulation to brain parenchyma peaked at 30 min after the injection into WT mice, but this was significantly blunted in esRAGE-overexpressing and RAGE-null mice. Significant reduction in 125I-labeled Aβ1-42-derived photo-stimulated luminescence were marked in ventricles, cerebral cortex, hippocampus, especially CA1 and CA3 regions, putamen, and thalamus. The results thus suggest the potential of esRAGE in protection against the development of Alzheimer's disease.

  18. Development of a monoclonal antibody-based ELISA system for glyceraldehyde-derived advanced glycation end products.

    PubMed

    Matsui, Takanori; Joo, Hoo Don; Lee, Jae Min; Ju, Sung Mi; Tao, Wang Hong; Higashimoto, Yuichiro; Fukami, Kei; Yamagishi, Sho-ichi

    2015-10-01

    We have previously found that glyceraldehyde-derived advanced glycation end products (glycer-AGEs) elicit oxidative stress generation and evoke inflammatory and thrombotic reactions through their higher binding affinity to RAGE (receptor for AGEs), thereby playing a role in vascular complications in diabetes. Furthermore, circulating levels of glycer-AGEs are elevated in diabetes. We characterized a monoclonal antibody (mAb) raised against glycer-AGEs and prepared its specific ELISA system in human serum. We developed here mAb reacted specifically with glycer-AGEs or glyceraldehyde-derived pyridinium, but not other structurally identified AGEs or AGE precursors. The mAb not only completely neutralized the deleterious effects of glycer-AGEs on endothelial cells, but also detected glycer-AGEs in the aorta of type 2 diabetic rats. Intra and inter-assay coefficient variations of the ELISA were 6 and 2.6%, respectively. ELISA linearity was shown intact within 5-fold dilution, and recovery ratio of added glycer-AGEs was 88-117%. Results of serum and plasma were comparable, and repeated freeze-thawing of samples did not affect the results (90.1-112.4%). Serum glycer-AGEs levels in 30 healthy subjects evaluated by the ELISA were strongly correlated with those by polyclonal Ab-based one (r=0.82). Our present study suggests the clinical utility of mAb for evaluating glycer-AGE levels in both tissue and serum.

  19. Advanced Glycation End Products Enhance Macrophages Polarization into M1 Phenotype through Activating RAGE/NF-κB Pathway.

    PubMed

    Jin, Xian; Yao, Tongqing; Zhou, Zhong'e; Zhu, Jian; Zhang, Song; Hu, Wei; Shen, Chengxing

    2015-01-01

    Atherosclerotic lesions are accelerated in patients with diabetes. M1 (classically activated in contrast to M2 alternatively activated) macrophages play key roles in the progression of atherosclerosis. Since advanced glycation end products (AGEs) are major pathogenic factors and active inflammation inducers in diabetes mellitus, this study assessed the effects of AGEs on macrophage polarization. The present study showed that AGEs significantly promoted macrophages to express IL-6 and TNF-α. M1 macrophage markers such as iNOS and surface markers including CD11c and CD86 were significantly upregulated while M2 macrophage markers such as Arg1 and CD206 remained unchanged after AGEs stimulation. AGEs significantly increased RAGE expression in macrophages and activated NF-κB pathway, and the aforementioned effects were partly abolished by administration of anti-RAGE antibody or NF-κB inhibitor PDTC. In conclusion, our results suggest that AGEs enhance macrophage differentiation into proinflammatory M1 phenotype at least partly via RAGE/NF-κB pathway activation.

  20. Food-advanced glycation end products aggravate the diabetic vascular complications via modulating the AGEs/RAGE pathway.

    PubMed

    Lv, Xing; Lv, Gao-Hong; Dai, Guo-Ying; Sun, Hong-Mei; Xu, Hui-Qin

    2016-11-01

    The aim of this study was to investigate the effects of high-advanced glycation end products (AGEs) diet on diabetic vascular complications. The Streptozocin (STZ)-induced diabetic mice were fed with high-AGEs diet. Diabetic characteristics, indicators of renal and cardiovascular functions, and pathohistology of pancreas, heart and renal were evaluated. AGEs/RAGE/ROS pathway parameters were determined. During the experiments, the diabetic mice exhibited typical characteristics including weight loss, polydipsia, polyphagia, polyuria, high-blood glucose, and low-serum insulin levels. However, high-AGEs diet effectively aggravated these diabetic characteristics. It also increased the 24-h urine protein levels, serum levels of urea nitrogen, creatinine, c-reactive protein (CRP), low density lipoprotein (LDL), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in the diabetic mice. High-AGEs diet deteriorated the histology of pancreas, heart, and kidneys, and caused structural alterations of endothelial cells, mesangial cells and podocytes in renal cortex. Eventually, high-AGEs diet contributed to the high-AGE levels in serum and kidneys, high-levels of reactive oxygen species (ROS) and low-levels of superoxide dismutase (SOD) in serum, heart, and kidneys. It also upregulated RAGE mRNA and protein expression in heart and kidneys. Our results showed that high-AGEs diet deteriorated vascular complications in the diabetic mice. The activation of AGEs/RAGE/ROS pathway may be involved in the pathogenesis of vascular complications in diabetes.

  1. Determination of advanced glycation endproducts by LC-MS/MS in raw and roasted almonds (Prunus dulcis).

    PubMed

    Zhang, Gong; Huang, Guangwei; Xiao, Lu; Mitchell, Alyson E

    2011-11-23

    A sensitive and reliable LC-(ESI)MS/MS method was developed and validated for the simultaneous analysis of five common advanced glycation endproducts (AGEs) after enzymatic digestion in raw and roasted almonds. AGEs included carboxymethyl-lysine (CML), carboxyethyl-lysine (CEL), pyralline (Pyr), argpyrimidine (Arg-p), and pentosidine (Pento-s). This method allows accurate quantitation of free and AGE-protein adducts of target AGEs. Results indicate that CML and CEL are found in both raw and roasted almonds. Pyr was identified for the first time in roasted almonds and accounted for 64.4% of free plus bound measured AGEs. Arg-p and Pento-s were below the limit of detection in all almond samples tested. Free AGEs accounted for 1.3-26.8% of free plus bound measured AGEs, indicating that protein-bound forms predominate. The roasting process significantly increased CML, CEL, and Pyr formation, but no significant correlation was observed between these AGEs and roasting temperature.

  2. Modeling the Interaction between Quinolinate and the Receptor for Advanced Glycation End Products (RAGE): Relevance for Early Neuropathological Processes

    PubMed Central

    Serratos, Iris N.; Castellanos, Pilar; Pastor, Nina; Millán-Pacheco, César; Rembao, Daniel; Pérez-Montfort, Ruy; Cabrera, Nallely; Reyes-Espinosa, Francisco; Díaz-Garrido, Paulina; López-Macay, Ambar; Martínez-Flores, Karina; López-Reyes, Alberto; Sánchez-García, Aurora; Cuevas, Elvis; Santamaria, Abel

    2015-01-01

    The receptor for advanced glycation end products (RAGE) is a pattern-recognition receptor involved in neurodegenerative and inflammatory disorders. RAGE induces cellular signaling upon binding to a variety of ligands. Evidence suggests that RAGE up-regulation is involved in quinolinate (QUIN)-induced toxicity. We investigated the QUIN-induced toxic events associated with early noxious responses, which might be linked to signaling cascades leading to cell death. The extent of early cellular damage caused by this receptor in the rat striatum was characterized by image processing methods. To document the direct interaction between QUIN and RAGE, we determined the binding constant (Kb) of RAGE (VC1 domain) with QUIN through a fluorescence assay. We modeled possible binding sites of QUIN to the VC1 domain for both rat and human RAGE. QUIN was found to bind at multiple sites to the VC1 dimer, each leading to particular mechanistic scenarios for the signaling evoked by QUIN binding, some of which directly alter RAGE oligomerization. This work contributes to the understanding of the phenomenon of RAGE-QUIN recognition, leading to the modulation of RAGE function. PMID:25757085

  3. Contribution of the toxic advanced glycation end-products-receptor axis in nonalcoholic steatohepatitis-related hepatocellular carcinoma

    PubMed Central

    Takino, Jun-ichi; Nagamine, Kentaro; Hori, Takamitsu; Sakasai-Sakai, Akiko; Takeuchi, Masayoshi

    2015-01-01

    Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. The main etiologies of HCC are hepatitis B virus and hepatitis C virus (HCV), and non-hepatitis B/non-hepatitis C HCC (NBNC-HCC) has also been identified as an etiological factor. Although the incidence of HCV-related HCC in Japan has decreased slightly in recent years, that of NBNC-HCC has increased. The onset mechanism of NBNC-HCC, which has various etiologies, remains unclear; however, nonalcoholic steatohepatitis (NASH), a severe form of nonalcoholic fatty liver disease, is known to be an important risk factor for NBNC-HCC. Among the different advanced glycation end-products (AGEs) formed by the Maillard reaction, glyceraldehyde-derived AGEs, the predominant components of toxic AGEs (TAGE), have been associated with NASH and NBNC-HCC, including NASH-related HCC. Furthermore, the expression of the receptor for AGEs (RAGE) has been correlated with the malignant progression of HCC. Therefore, TAGE induce oxidative stress by binding with RAGE may, in turn, lead to adverse effects, such as fibrosis and malignant transformation, in hepatic stellate cells and tumor cells during NASH or NASH-related HCC progression. The aim of this review was to examine the contribution of the TAGE-RAGE axis in NASH-related HCC. PMID:26483867

  4. Involvement of Endoplasmic Reticulum Stress, Autophagy, and Apoptosis in Advanced Glycation End Products-Induced Glomerular Mesangial Cell Injury

    PubMed Central

    Chiang, Chih-Kang; Wang, Ching-Chia; Lu, Tien-Fong; Huang, Kuo-How; Sheu, Meei-Ling; Liu, Shing-Hwa; Hung, Kuan-Yu

    2016-01-01

    Advanced glycation end-products (AGEs)-induced mesangial cell death is one of major causes of glomerulus dysfunction in diabetic nephropathy. Both endoplasmic reticulum (ER) stress and autophagy are adaptive responses in cells under environmental stress and participate in the renal diseases. The role of ER stress and autophagy in AGEs-induced mesangial cell death is still unclear. Here, we investigated the effect and mechanism of AGEs on glomerular mesangial cells. AGEs dose-dependently decreased mesangial cell viability and induced cell apoptosis. AGEs also induced ER stress signals in a time- and dose-dependent manner. Inhibition of ER stress with 4-phenylbutyric acid effectively inhibited the activation of eIF2α and CHOP signals and reversed AGEs-induced cell apoptosis. AGEs also activated LC-3 cleavage, increased Atg5 expression, and decreased p62 expression, which indicated the autophagy induction in mesangial cells. Inhibition of autophagy by Atg5 siRNAs transfection aggravated AGEs-induced mesangial cell apoptosis. Moreover, ER stress inhibition by 4-phenylbutyric acid significantly reversed AGEs-induced autophagy, but autophagy inhibition did not influence the AGEs-induced ER stress-related signals activation. These results suggest that AGEs induce mesangial cell apoptosis via an ER stress-triggered signaling pathway. Atg5-dependent autophagy plays a protective role. These findings may offer a new strategy against AGEs toxicity in the kidney. PMID:27665710

  5. Autophagy Protects Advanced Glycation End Product-Induced Apoptosis and Expression of MMP-3 and MMP-13 in Rat Chondrocytes

    PubMed Central

    Wu, Tianlong

    2017-01-01

    Aging is one of the most prominent risk factors for the pathological progression of osteoarthritis (OA). One feature of age-related changes in OA is advanced glycation end products (AGEs) accumulation in articular cartilage. Autophagy plays a cellular housekeeping role by removing dysfunctional cellular organelles and proteins. However, the relationship between autophagy and AGE-associated OA is unknown. The aim of this study is to determine whether autophagy participates in the pathology of AGE-treated chondrocytes and to investigate the exact role of autophagy in AGE-induced cell apoptosis and expression of matrix metalloproteinase- (MMP-) 3 and MMP-13. AGEs induced notable apoptosis that was detected by Annexin V/PI double-staining, and the upregulation of MMP-3 and MMP-13 was confirmed by Western blotting. Autophagy-related proteins were also determined by Western blotting, and chondrocytes were transfected with mCherry-GFP-LC3B-adenovirus to monitor autophagic flux. As a result, autophagy significantly increased in chondrocytes and peaked at 6 h. Furthermore, rapamycin (RA) attenuated AGE-induced apoptosis and expression of MMP-3 and MMP-13 by autophagy activation. In contrast, pretreatment with autophagy inhibitor 3-methyladenine (3-MA) enhanced the abovementioned effects of AGEs. We therefore demonstrated that autophagy is linked with AGE-related pathology in rat chondrocytes and plays a protective role in AGE-induced apoptosis and expression of MMP-3 and MMP-13. PMID:28265573

  6. The downregulation of thioredoxin accelerated Neuro2a cell apoptosis induced by advanced glycation end product via activating several pathways.

    PubMed

    Ren, Xiang; Ma, Haiying; Qiu, Yuanyuan; Liu, Bo; Qi, Hui; Li, Zeyu; Kong, Hui; Kong, Li

    2015-08-01

    Thioredoxin (Trx), a 12 kDa protein, has different functions in different cellular environments, playing important anti-oxidative and anti-apoptotic roles and regulating the expression of transcription factors. Advanced glycation end products (AGEs) are a heterogeneous group of irreversible adducts from glucose-protein condensation reactions and are considered crucial to the development of diabetic nephropathy, retinopathy, neurodegeneration and atherosclerosis. The aim of this study was to use a Trx inhibitor to investigate the effects and mechanism of Trx down-regulation on AGE-induced Neuro2a cell apoptosis. Neuro2a cells were cultured in vitro and treated with different conditions. The apoptosis and proliferation of Neuro2a cells were detected using flow cytometry, DNA-Ladder and CCK8 assays. Rho 123 was used to detect the mitochondrial membrane potential. ROS generation and caspase3 activity were detected using a DCFH-DA probe and micro-plate reader. Western blotting and real-time PCR were used to detect the expression of proteins and genes. We found that the down-regulation of thioredoxin could accelerate AGE-induced apoptosis in Neuro2a cells. A possible underlying mechanism is that the down-regulation of thioredoxin stimulated the up-regulation of ASK1, p-JNK, PTEN, and Txnip, as well as the down-regulation of p-AKT, ultimately increasing ROS levels and caspase3 activity.

  7. Advanced glycation end products impair function of late endothelial progenitor cells through effects on protein kinase Akt and cyclooxygenase-2

    SciTech Connect

    Chen Qin; Dong Li; Wang Lian; Kang Lina; Xu Biao

    2009-04-03

    Endothelial progenitor cells (EPCs) exhibit impaired function in the context of diabetes, and advanced glycation end products (AGEs), which accumulate in diabetes, may contribute to this. In the present study, we investigated the mechanism by which AGEs impair late EPC function. EPCs from human umbilical cord blood were isolated, and incubated with AGE-modified albumin (AGE-albumin) at different concentrations found physiologically in plasma. Apoptosis, migration, and tube formation assays were used to evaluate EPC function including capacity for vasculogenesis, and expression of the receptor for AGEs (RAGE), Akt, endothelial nitric oxide synthase (eNOS), and cycloxygenase-2 (COX-2) were determined. Anti-RAGE antibody was used to block RAGE function. AGE-albumin concentration-dependently enhanced apoptosis and depressed migration and tube formation, but did not affect proliferation, of late EPCs. High AGE-albumin increased RAGE mRNA and protein expression, and decreased Akt and COX-2 protein expression, whilst having no effect on eNOS mRNA or protein in these cells. These effects were inhibited by co-incubation with anti-RAGE antibody. These results suggest that RAGE mediates the AGE-induced impairment of late EPC function, through down-regulation of Akt and COX-2 in these cells.

  8. Comprehensive analyses of how tubule occlusion and advanced glycation end-products diminish strength of aged dentin

    PubMed Central

    Shinno, Yuko; Ishimoto, Takuya; Saito, Mitsuru; Uemura, Reo; Arino, Masumi; Marumo, Keishi; Nakano, Takayoshi; Hayashi, Mikako

    2016-01-01

    In clinical dentistry, since fracture is a major cause of tooth loss, better understanding of mechanical properties of teeth structures is important. Dentin, the major hard tissue of teeth, has similar composition to bone. In this study, we investigated the mechanical properties of human dentin not only in terms of mineral density but also using structural and quality parameters as recently accepted in evaluating bone strength. Aged crown and root dentin (age ≥ 40) exhibited significantly lower flexural strength and toughness than young dentin (age < 40). Aged dentin, in which the dentinal tubules were occluded with calcified material, recorded the highest mineral density; but showed significantly lower flexural strength than young dentin. Dentin with strong alignment of the c-axis in hydroxyapatite exhibited high fracture strength, possibly because the aligned apatite along the collagen fibrils may reinforce the intertubular dentin. Aged dentin, showing a high advanced glycation end-products (AGEs) level in its collagen, recorded low flexural strength. We first comprehensively identified significant factors, which affected the inferior mechanical properties of aged dentin. The low mechanical strength of aged dentin is caused by the high mineral density resulting from occlusion of dentinal tubules and accumulation of AGEs in dentin collagen. PMID:26797297

  9. Systemic activation of NF-κB driven luciferase activity in transgenic mice fed advanced glycation end products modified albumin.

    PubMed

    Nass, Norbert; Bayreuther, Kristina; Simm, Andreas

    2017-04-01

    Advanced glycation end products (AGEs) are stable end products of the Maillard reaction and accumulate with progressing ageing and degenerative diseases. Significant amounts of AGE-modified peptides are also consumed with processed food. AGEs bind to specific receptors, especially the receptor of AGEs (RAGE). Activation of RAGE then evokes intracellular signalling, finally resulting in the activation of the NF-κB transcription factor and therefore a proinflammatory state. We here analysed, whether NF-κB is activated in short term upon feeding an AGE-modified protein in-vivo. Transgenic mice expressing firefly luciferase under the control of an NF-κB responsive promoter were intraperitoneally injected or fed with AGE-modified- or control albumin and luciferase expression was analysed by in-vivo imaging and by in-vitro by determination of luciferase enzyme activity in heart, lung, gut, spleen, liver and kidney. In all organs, an activation of the luciferase reporter gene was observed in response to AGE-BSA feeding, however with different intensity and timing. The gut exhibited highest luciferase activity and this activity peaked 6-8 h post AGE-feeding. In heart and kidney, luciferase activity increased for up to 12 h post feeding. All other organs tested, exhibited highest activity at 10 h after AGE-consumption. Altogether, these data demonstrate that feeding AGE-modified protein resulted in a transient and systemic activation of the NF-κB reporter.

  10. The promoter polymorphisms of receptor for advanced glycation end products were associated with the susceptibility and progression of sepsis.

    PubMed

    Shao, Y; Shao, X; He, J; Cai, Y; Zhao, J; Chen, F; Tao, H; Yin, Z; Tan, X; He, Y; Lin, Y; Li, K; Cui, L

    2017-04-01

    Receptor for advanced glycation end products (RAGE) is considered a major pattern recognition receptor, which plays an important role in the development of sepsis. Increasing evidence showed an association between RAGE polymorphisms and the susceptibility to several inflammatory-related diseases. However, little is known about the clinical relationship between RAGE polymorphisms and sepsis. In this study, we analyzed the association of sepsis with three functional RAGE gene polymorphisms (rs1800624, rs1800625 and rs2070600) in a Chinese Han population (372 sepsis cases and 400 healthy controls). Significant differences were observed in the rs1800624 and rs1800625 genotype/allele distributions between the sepsis and controls, but no significant difference was observed in the rs2070600 genotype/allele. Moreover, our results also revealed a significant difference in the genotype/allele frequencies of the rs1800624 and rs1800625 polymorphisms between the sepsis and severe sepsis subtypes, the rs1800624 TT or rs1800625 TT genotype carriers exhibited a significant increase in RAGE mRNA, sRAGE, TNF-α and IL-6 expression compared with the rs1800624 AT/AA or rs1800625 CT/CC carriers in sepsis patients. Overall, this study might provide valuable clinical evidence between the RAGE gene polymorphisms and the risk or the development of sepsis.

  11. Overexpression of receptor for advanced glycation end products and high-mobility group box 1 in human dental pulp inflammation.

    PubMed

    Tancharoen, Salunya; Tengrungsun, Tassanee; Suddhasthira, Theeralaksna; Kikuchi, Kiyoshi; Vechvongvan, Nuttavun; Tokuda, Masayuki; Maruyama, Ikuro

    2014-01-01

    High mobility group box 1 (HMGB1), a nonhistone DNA-binding protein, is released into the extracellular space and promotes inflammation. HMGB1 binds to related cell signaling transduction receptors, including receptor for advanced glycation end products (RAGE), which actively participate in vascular and inflammatory diseases. The aim of this study was to examine whether RAGE and HMGB1 are involved in the pathogenesis of pulpitis and investigate the effect of Prevotella intermedia (P. intermedia) lipopolysaccharide (LPS) on RAGE and HMGB1 expression in odontoblast-like cells (OLC-1). RAGE and HMGB1 expression levels in clinically inflamed dental pulp were higher than those in healthy dental pulp. Upregulated expression of RAGE was observed in odontoblasts, stromal pulp fibroblasts-like cells, and endothelial-like cell lining human pulpitis tissue. Strong cytoplasmic HMGB1 immunoreactivity was noted in odontoblasts, whereas nuclear HMGB1 immunoreactivity was seen in stromal pulp fibroblasts-like cells in human pulpitis tissue. LPS stimulated OLC-1 cells produced HMGB1 in a dose-dependent manner through RAGE. HMGB1 translocation towards the cytoplasm and secretion from OLC-1 in response to LPS was inhibited by TPCA-1, an inhibitor of NF-κB activation. These findings suggest that RAGE and HMGB1 play an important role in the pulpal immune response to oral bacterial infection.

  12. Receptor for advanced glycation end products Glycine 82 Serine polymorphism and risk of cardiovascular events in rheumatoid arthritis.

    PubMed

    Carroll, Lisa; Frazer, Ian H; Turner, Malcolm; Marwick, Thomas H; Thomas, Ranjeny

    2007-01-01

    Patients with rheumatoid arthritis (RA) are at risk of excess mortality, predominantly owing to cardiovascular (CV) events. The receptor for advanced glycation end products (RAGE) has been implicated in the perpetuation of the chronic inflammatory response in vascular disease. A Gly82-->Ser polymorphism in the RAGE gene, which is associated with enhanced RAGE signaling, is present more frequently in patients with RA than the general population. To investigate whether RAGE Gly82-->Ser polymorphism is associated with CV events in RA, we examined CV events, CV risk factors, features of RA and RAGE Gly82-->Ser polymorphism in 232 patients with RA attending a tertiary referral hospital. CV events, the duration and severity of RA, and risk factors for CV disease were determined using patient questionnaires, chart review, laboratory analysis and radiographs. DNA was typed for HLA-DRB1 genes and RAGE Gly82-->Ser polymorphism. The RAGE Ser82 allele, which is in linkage disequilibrium with the RA susceptibility allele HLA-DRB1*0401, was carried by 20% of patients. More than 20% of the cohort had suffered a vascular event; a shorter duration of RA, but not the RAGE genotype, was significantly associated with CV events. However, a history of statin use was protective. Thus, the RAGE Ser82 allele, associated with enhanced RAGE signaling, does not predispose to CV events in RA. However, treatment of hyperlipidemia with statins reduces the probability of a CV event.

  13. Dihydroxyacetone-induced death is accompanied by advanced glycation endproduct formation in selected proteins of Saccharomyces cerevisiae and Caenorhabditis elegans.

    PubMed

    Molin, Mikael; Pilon, Marc; Blomberg, Anders

    2007-10-01

    Advanced glycation endproduct (AGE) formation is an important mechanism for protein deterioration during diabetic complications and ageing. The effects on AGE formation following dihydroxyacetone (DHA) stress were studied in two model organisms, the yeast Saccharomyces cerevisiae and the nematode Caenorhabditis elegans. Total protein AGEs, detected using an anti-N(epsilon)-carboxyalkyllysine-specific monoclonal antibody, displayed a strong correlation to DHA-induced yeast cell mortality in the wild-type and hypersensitive as well as resistant mutant strains. During DHA-induced cell death we also detected AGEs as the formation of acidic protein modifications by 2-D PAGE. Furthermore, we confirmed AGE targets immunologically on 2-D gel-separated protein extracted from DHA-treated cells. AGE modification of several metabolic enzymes (Eno2p, Adh1p, Met6 and Pgk1p) and actin (Act1p) displayed a strong correlation to DHA-induced cell death. DHA was toxic to C. elegans even at low concentration and also in this organism AGE formation accompanied death. We propose the use of DHA as a model AGE-generating substance for its apparent lack of a clear oxidative stress connection, and yeast and worm as model organisms to identify genetic determinants of protein AGE formation.

  14. Comprehensive analyses of how tubule occlusion and advanced glycation end-products diminish strength of aged dentin

    NASA Astrophysics Data System (ADS)

    Shinno, Yuko; Ishimoto, Takuya; Saito, Mitsuru; Uemura, Reo; Arino, Masumi; Marumo, Keishi; Nakano, Takayoshi; Hayashi, Mikako

    2016-01-01

    In clinical dentistry, since fracture is a major cause of tooth loss, better understanding of mechanical properties of teeth structures is important. Dentin, the major hard tissue of teeth, has similar composition to bone. In this study, we investigated the mechanical properties of human dentin not only in terms of mineral density but also using structural and quality parameters as recently accepted in evaluating bone strength. Aged crown and root dentin (age ≥ 40) exhibited significantly lower flexural strength and toughness than young dentin (age < 40). Aged dentin, in which the dentinal tubules were occluded with calcified material, recorded the highest mineral density; but showed significantly lower flexural strength than young dentin. Dentin with strong alignment of the c-axis in hydroxyapatite exhibited high fracture strength, possibly because the aligned apatite along the collagen fibrils may reinforce the intertubular dentin. Aged dentin, showing a high advanced glycation end-products (AGEs) level in its collagen, recorded low flexural strength. We first comprehensively identified significant factors, which affected the inferior mechanical properties of aged dentin. The low mechanical strength of aged dentin is caused by the high mineral density resulting from occlusion of dentinal tubules and accumulation of AGEs in dentin collagen.

  15. Levels of Soluble Receptor for Advanced Glycation End Products in Bronchoalveolar Lavage Fluid in Patients with Various Inflammatory Lung Diseases

    PubMed Central

    Kamo, Tetsuro; Tasaka, Sadatomo; Tokuda, Yuriko; Suzuki, Shoji; Asakura, Takanori; Yagi, Kazuma; Namkoong, Ho; Ishii, Makoto; Hasegawa, Naoki; Betsuyaku, Tomoko

    2015-01-01

    Receptor for advanced glycation end products (RAGE) is a multiligand receptor of S100/calgranulins, high-mobility group box 1, and others, and it is associated with the pathogenesis of various inflammatory and circulatory diseases. The soluble form of RAGE (sRAGE) is a decoy receptor and competitively inhibits membrane-bound RAGE activation. In this study, we measured sRAGE levels in bronchoalveolar lavage fluid (BALF) of 78 patients, including 41 with interstitial pneumonia, 11 with sarcoidosis, 9 with respiratory infection, 7 with ARDS, 5 with lung cancer, and 5 with vasculitis. Among them, sRAGE was detectable in BALF of 73 patients (94%). In patients with ARDS and vasculitis, the sRAGE levels were significantly higher than in the control subjects and those with interstitial pneumonia. The sRAGE levels were positively correlated with total cell counts in BALF and serum levels of surfactant protein-D, lactate dehydrogenase, and C-reactive protein. There was an inverse correlation between PaO2/FIO2 ratio and sRAGE levels. These results indicate that sRAGE in BALF might be considered as a biomarker of lung inflammatory disorders, especially ARDS and vasculitis. PMID:27147899

  16. Association of Polymorphisms of the Receptor for Advanced Glycation Endproducts Gene with Schizophrenia in a Han Chinese Population

    PubMed Central

    Fu, Jiawu; Zuo, Xiang; Yin, Jingwen; Luo, Xudong; Li, Zheng; Lin, Juda

    2017-01-01

    Receptor for Advanced Glycation Endproducts (RAGE) is a member of the immunoglobulin superfamily that binds diverse ligands involved in the development of inflammatory damage and diverse chronic diseases including schizophrenia. Here, three single-nucleotide polymorphisms (SNPs) (G82S, -374T/A, and -429T/C) in the RAGE gene were genotyped in 923 patients with schizophrenia and 874 healthy-matched controls in a Han Chinese population using the SNaPshot technique. Additionally, we investigated the association among aforementioned SNPs with the clinical psychotic symptoms of the patients and neurocognitive function. Our study demonstrated that the frequencies of the TC + CC genotypes and the C allele in the -429T/C polymorphism were significantly lower in the patients compared with the controls (p = 0.031 and p = 0.034, resp.). However, the significant effect disappeared when using Bonferroni correction (p = 0.093 and p = 0.102, resp.). And there were no significant differences in the genotype and allele frequencies between the patients and the controls for G82S and -374T/A polymorphisms. Additionally, the -429T/C C allele carriers had marginally higher Symbol coding scores than the subjects with the TT genotypes [p = 0.031 and p (corr) = 0.093]. Our data indicate that the RAGE -429T/C polymorphism may be associated with the susceptibility of schizophrenia. PMID:28373983

  17. Advanced Glycation End Products Enhance Macrophages Polarization into M1 Phenotype through Activating RAGE/NF-κB Pathway

    PubMed Central

    Jin, Xian; Yao, Tongqing; Zhou, Zhong'e; Zhu, Jian; Zhang, Song; Hu, Wei; Shen, Chengxing

    2015-01-01

    Atherosclerotic lesions are accelerated in patients with diabetes. M1 (classically activated in contrast to M2 alternatively activated) macrophages play key roles in the progression of atherosclerosis. Since advanced glycation end products (AGEs) are major pathogenic factors and active inflammation inducers in diabetes mellitus, this study assessed the effects of AGEs on macrophage polarization. The present study showed that AGEs significantly promoted macrophages to express IL-6 and TNF-α. M1 macrophage markers such as iNOS and surface markers including CD11c and CD86 were significantly upregulated while M2 macrophage markers such as Arg1 and CD206 remained unchanged after AGEs stimulation. AGEs significantly increased RAGE expression in macrophages and activated NF-κB pathway, and the aforementioned effects were partly abolished by administration of anti-RAGE antibody or NF-κB inhibitor PDTC. In conclusion, our results suggest that AGEs enhance macrophage differentiation into proinflammatory M1 phenotype at least partly via RAGE/NF-κB pathway activation. PMID:26114112

  18. Phenolics from Garcinia mangostana Inhibit Advanced Glycation Endproducts Formation: Effect on Amadori Products, Cross-Linked Structures and Protein Thiols.

    PubMed

    Abdallah, Hossam M; El-Bassossy, Hany; Mohamed, Gamal A; El-Halawany, Ali M; Alshali, Khalid Z; Banjar, Zainy M

    2016-02-22

    Accumulation of Advanced Glycation Endproducts (AGEs) in body tissues plays a major role in the development of diabetic complications. Here, the inhibitory effect of bioactive metabolites isolated from fruit hulls of Garcinia mangostana on AGE formation was investigated through bio-guided approach using aminoguanidine (AG) as a positive control. Including G. mangostana total methanol extract (GMT) in the reaction mixture of bovine serum albumin (BSA) and glucose or ribose inhibited the fluorescent and non-fluorescent AGEs formation in a dose dependent manner. The bioassay guided fractionation of GMT revealed isolation of four bioactive constituents from the bioactive fraction; which were identified as: garcimangosone D (1), aromadendrin-8-C-glucopyranoside (2), epicatechin (3), and 2,3',4,5',6-pentahydroxybenzophenone (4). All the tested compounds significantly inhibited fluorescent and non-fluorescent AGEs formation in a dose dependent manner whereas compound 3 (epicatechin) was found to be the most potent. In search for the level of action, addition of GMT, and compounds 2-4 inhibited fructosamine (Amadori product) and protein aggregation formation in both glucose and ribose. To explore the mechanism of action, it was found that addition of GMT and only compound (3) to reaction mixture increased protein thiol in both glucose and ribose while compounds 1, 2 and 4 only increased thiol in case of ribose. In conclusion, phenolic compounds 1-4 inhibited AGEs formation at the levels of Amadori product and protein aggregation formation through saving protein thiol.

  19. Inhibition of advanced glycation end products by red grape skin extract and its antioxidant activity

    PubMed Central

    2013-01-01

    Background The objective of the present study was to determine the phytochemical content and the protective effect of red grape skin extract (RGSE) against fructose-mediated protein oxidation. In addition, RGSE was screened for its potential as an antioxidant using various in vitro models. Methods Antioxidant activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical scavenging activity, superoxide radical scavenging activity, trolox equivalent antioxidant capacity, ferric reducing antioxidant power (FRAP), ferrous ion chelating power. The total phenols content was measured by Folin–Ciocalteu assay, the flavonoids content by the AlCl3 colorimetric method. Antiglycation activity was determined using the formation of AGE fluorescence intensity, Nϵ-(carboxymethyl)lysine, and the level of fructosamine. The protein oxidation was examined using the level of protein carbonyl content and thiol group. Results The results showed that the content of total phenolics, flavonoids and total anthocyanins in RGSE was 246.3 ± 0.9 mg gallic acid equivalent/g dried extract, 215.9 ± 1.3 mg catechin equivalent/g dried extract, and 36.7 ± 0.8 mg cyanidin-3-glucoside equivalent/g dried extract, respectively. In the DPPH radical scavenging activity, hydroxyl radical scavenging activity, and superoxide radical scavenging activity, RGSE had the IC50 values of 0.03 ± 0.01 mg/ml, 5.40 ± 0.01 mg/ml, and 0.58 ± 0.01 mg/ml, respectively. In addition, RGSE had trolox equivalent antioxidant capacity assay (395.65 ± 1.61 mg trolox equivalent/g dried extract), ferric reducing antioxidant power (114.24 ± 0.03 mM FeSO4/g dried extract), and ferrous ion chelating power (3,474.05 ± 5.55 mg EDTA/g dried extract), respectively. The results showed that RGSE at different concentrations (0.031–0.500 mg/ml) has significantly inhibited the formation of AGEs in terms of the fluorescence intensity of glycated BSA during 4 weeks of study. The

  20. Advanced oxidation protein products induce chondrocyte apoptosis via receptor for advanced glycation end products-mediated, redox-dependent intrinsic apoptosis pathway.

    PubMed

    Wu, Qian; Zhong, Zhao-Ming; Zhu, Si-Yuan; Liao, Cong-Rui; Pan, Ying; Zeng, Ji-Huan; Zheng, Shuai; Ding, Ruo-Ting; Lin, Qing-Song; Ye, Qing; Ye, Wen-Bin; Li, Wei; Chen, Jian-Ting

    2016-01-01

    Pro-inflammatory cytokine-induced chondrocyte apoptosis is a primary cause of cartilage destruction in the progression of rheumatoid arthritis (RA). Advanced oxidation protein products (AOPPs), a novel pro-inflammatory mediator, have been confirmed to accumulate in patients with RA. However, the effect of AOPPs accumulation on chondrocyte apoptosis and the associated cellular mechanisms remains unclear. The present study demonstrated that the plasma formation of AOPPs was enhanced in RA rats compared with normal. Then, chondrocyte were treated with AOPPs-modified rat serum albumin (AOPPs-RSA) in vitro. Exposure of chondrocyte to AOPPs activated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and increased expression of NADPH oxidase subunits, which was mediated by receptor for advanced glycation end products (RAGE), but not scavenger receptor CD36. Moreover, AOPPs challenge triggered NADPH oxidase-dependent ROS generation which induced mitochondrial dysfunction and endoplasmic reticulum stress resulted in activation of caspase family that eventually lead to apoptosis. Lastly, blockade of RAGE, instead of CD36, largely attenuated these signals. Our study demonstrated first time that AOPPs induce chondrocyte apoptosis via RAGE-mediated and redox-dependent intrinsic apoptosis pathway in vitro. These data implicates that AOPPs may represent a novel pathogenic factor that contributes to RA progression. Targeting AOPPs-triggered cellular mechanisms might emerge as a promising therapeutic option for patients with RA.

  1. Olive leaf extract concentrated in hydroxytyrosol attenuates protein carbonylation and the formation of advanced glycation end products in a hepatic cell line (HepG2).

    PubMed

    Navarro, Marta; Morales, Francisco J; Ramos, Sonia

    2017-03-22

    Glycation takes place both at the cellular level and at the extracellular matrix level and generates, consequently, advanced glycation end-products (AGEs) associated with chronic diseases and the aging process. Two olive leaf extracts concentrated in (i) oleuropein (OLE-A; 93.9 mg oleuropein g(-1)) and (ii) hydroxytyrosol (OLE-B; 54.5 mg hydroxytyrosol g(-1)) were evaluated according to their antiglycative and antioxidant capacity in vitro. OLE-B exerted the highest anti-AGE effect in different glycation models (IC50: 0.25-0.29 mg mL(-1)). OLE-B showed the highest antioxidant capacity and methylglyoxal-trapping capacity (IC50 0.16 mg mL(-1)). OLE-B showed a significant inhibitory effect against protein carbonylation (21%) and generation of argpyrimidine (26%) in a hepatocyte cellular carbonyl stress model evoked by methylglyoxal (MGO). OLE-B was further fractionated by solid phase-extraction, and the protective effect against protein carbonylation was only exerted by the fraction containing hydroxytyrosol. However, hydroxytyrosol standard, at the same concentration in the extract, inhibited the protein carbonylation below 10% but not significantly. The results indicate that the antiglycative activity of OLE in cells could be due to a synergic effect of hydroxytyrosol and other minor compounds with similar polarity. The research of the antiglycative activity in vivo could confirm these promising results and to propose OLE as a natural anti-AGE agent.

  2. Dietary advanced glycation end products restriction diminishes inflammation markers and oxidative stress in patients with type 2 diabetes mellitus.

    PubMed

    Luévano-Contreras, Claudia; Garay-Sevilla, Ma Eugenia; Wrobel, Kazimierz; Malacara, Juan M; Wrobel, Katarzyna

    2013-01-01

    The augmented consumption of dietary advanced glycation end products (dAGEs) has been associated with increased oxidative stress and inflammation, however, there is insufficient information over the effect on insulin resistance. The objective of the present study is to investigate the effect of dAGEs restriction on tumor necrosis factor-α (TNF-α), malondialdehyde, C-reactive protein (CRP), and insulin resistance in DM2 patients. We carried out a randomized 6 weeks prospective study in two groups of patients: subjects with a standard diet (n = 13), vs low dAGEs (n = 13). At the beginning and the end of study, we collected anthropometric measurements, and values of circulating glucose, HbA1c, lipids, insulin, serum AGEs, CRP, TNF-α and malondialdehyde. Anthropometric measurements, glucose, and lipids were similar in both groups at base line and at the end of the study. Estimation of basal dAGEs was similar in both groups; after 6 weeks it was unchanged in the standard group but in the low dAGEs group decreased by 44% (p<0.0002). Changes in TNF-α levels were different under standard diet (12.5 ± 14.7) as compared with low dAGEs (-18.36 ± 17.1, p<0.00001); changes in malondialdehyde were different in the respective groups (2.0 ± 2.61 and -0.83 ± 2.0, p<0.005) no changes were found for insulin levels or HOMA-IR. In conclusion, The dAGEs restriction decreased significantly TNF-α and malondialdehyde levels.

  3. Accelerated Aging in Glaucoma: Immunohistochemical Assessment of Advanced Glycation End Products in the Human Retina and Optic Nerve Head

    PubMed Central

    Tezel, Gülgün; Luo, Cheng; Yang, Xiangjun

    2008-01-01

    PURPOSE This study aimed to determine the association between advanced glycation end products (AGEs) and glaucoma based on the known synergism between oxidative stress with AGEs and the evidence of oxidative stress during glaucomatous neurodegeneration. METHODS The extent and cellular localization of immunolabeling for AGEs and their receptor, RAGE, were determined in histologic sections of the retina and optic nerve head obtained from 38 donor eyes with glaucoma and 30 eyes from age-matched donors without glaucoma. RESULTS The extent of AGE and RAGE immunolabeling was greater in older than in younger donor eyes. However, compared with age-matched controls, an enhanced accumulation of AGEs and an up-regulation of RAGE were detectable in the glaucomatous retina and optic nerve head. Although some retinal ganglion cells (RGCs) and glia exhibited intracellular immunolabeling for AGEs, increased AGE immunolabeling in glaucomatous eyes was predominantly extracellular and included laminar cribriform plates in the optic nerve head. Some RAGE immunolabeling was detectable on RGCs; however, increased RAGE immunolabeling in glaucomatous eyes was predominant on glial cells, primarily Müller cells. CONCLUSIONS Given that the generation of AGEs is an age-dependent event, increased AGE accumulation in glaucomatous tissues supports that an accelerated aging process accompanies neurodegeneration in glaucomatous eyes. One of the potential consequences of AGE accumulation in glaucomatous eyes appears to be its contribution to increased rigidity of the lamina cribrosa. The presence of RAGE on RGCs and glia also makes them susceptible to AGE-mediated events through receptor-mediated signaling, which may promote cell death or dysfunction during glaucomatous neurodegeneration. PMID:17325164

  4. Advanced glycation endproducts increase proliferation, migration and invasion of the breast cancer cell line MDA-MB-231.

    PubMed

    Sharaf, Hana; Matou-Nasri, Sabine; Wang, Qiuyu; Rabhan, Zaki; Al-Eidi, Hamad; Al Abdulrahman, Abdulkareem; Ahmed, Nessar

    2015-03-01

    Diabetic patients have increased likelihood of developing breast cancer. Advanced glycation endproducts (AGEs) underlie the pathogenesis of diabetic complications but their impact on breast cancer cells is not understood. This study aims to determine the effects of methylglyoxal-derived bovine serum albumin AGEs (MG-BSA-AGEs) on the invasive MDA-MB-231 breast cancer cell line. By performing cell counting, using wound-healing assay, invasion assay and zymography analysis, we found that MG-BSA-AGEs increased MDA-MB-231 cell proliferation, migration and invasion through Matrigel™ associated with an enhancement of matrix metalloproteinase (MMP)-9 activities, in a dose-dependent manner. Using Western blot and flow cytometry analyses, we demonstrated that MG-BSA-AGEs increased expression of the receptor for AGEs (RAGE) and phosphorylation of key signaling protein extracellular signal-regulated kinase (ERK)-1/2. Furthermore, in MG-BSA-AGE-treated cells, phospho-protein micro-array analysis revealed enhancement of phosphorylation of the ribosomal protein 70 serine S6 kinase beta 1 (p70S6K1), which is known to be involved in protein synthesis, the signal transducer and activator of transcription (STAT)-3 and the mitogen-activated protein kinase (MAPK) p38, which are involved in cell survival. Blockade of MG-BSA-AGE/RAGE interactions using a neutralizing anti-RAGE antibody inhibited MG-BSA-AGE-induced MDA-MB-231 cell processes, including the activation of signaling pathways. Throughout the study, non-modified BSA had a negligible effect. In conclusion, AGEs might contribute to breast cancer development and progression partially through the regulation of MMP-9 activity and RAGE signal activation. The up-regulation of RAGE and the concomitant increased phosphorylation of p70S6K1 induced by AGEs may represent promising targets for drug therapy to treat diabetic patients with breast cancer.

  5. Curcumin inhibits advanced glycation end product-induced oxidative stress and inflammatory responses in endothelial cell damage via trapping methylglyoxal.

    PubMed

    Sun, Yan Ping; Gu, Jun Fei; Tan, Xiao Bin; Wang, Chun Fei; Jia, Xiao Bin; Feng, Liang; Liu, Ji Ping

    2016-02-01

    Methylglyoxal (MGO)-induced carbonyl stress and pro-inflammatory responses have been suggested to contribute to endothelial dysfunction. Curcumin (Cur), a polyphenolic compound from Curcuma longa L., may protect endothelial cells against carbonyl stress-induced damage by trapping dicarbonyl compounds such as MGO. However, Cur-MGO adducts have not been studied in depth to date and it remains to be known whether Cur-MGO adducts are able to attenuate endothelial damage by trapping MGO. In the present study, 1,2-diaminobenzene was reacted with MGO to ensure the reliability of the reaction system. Cur was demonstrated to trap MGO at a 1:1 ratio to form adducts 1, 2 and 3 within 720 min. The structures of these adducts were identified by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry. The kinetic curves of Cur (10(-7), 10(-6) and 10(-5) M) were measured from 0-168 h by fluorescent intensity. Cur significantly inhibited the formation of advanced glycation end products (AGEs). The differences in oxidative damage and the levels of pro-inflammatory cytokines following MGO + HSA or Cur-MGO treatment were investigated in human umbilical vein endothelial cells (HUVECs). Exposure of HUVECs to the Cur-MGO reaction adducts significantly reduced the intracellular ROS levels and improved cell viability compared with MGO alone. Furthermore, there was a significant reduction in the expression levels of transforming growth factor-β1 and intercellular adhesion molecule(-1) following treatment with Cur-MGO adducts compared with MGO alone. These results provide further evidence that the trapping of MGO by Cur inhibits the formation of AGEs. The current study indicates that the protective effect of Cur on carbonyl stress and pro-inflammatory responses in endothelial damage occurs via the trapping of MGO.

  6. Chronic ingestion of advanced glycation end products induces degenerative spinal changes and hypertrophy in aging pre-diabetic mice.

    PubMed

    Illien-Jünger, Svenja; Lu, Young; Qureshi, Sheeraz A; Hecht, Andrew C; Cai, Weijing; Vlassara, Helen; Striker, Gary E; Iatridis, James C

    2015-01-01

    Intervertebral disc (IVD) degeneration and pathological spinal changes are major causes of back pain, which is the top cause of global disability. Obese and diabetic individuals are at increased risk for back pain and musculoskeletal complications. Modern diets contain high levels of advanced glycation end products (AGEs), cyto-toxic components which are known contributors to obesity, diabetes and accelerated aging pathologies. There is little information about potential effects of AGE rich diet on spinal pathology, which may be a contributing cause for back pain which is common in obese and diabetic individuals. This study investigated the role of specific AGE precursors (e.g. methylglyoxal-derivatives (MG)) on IVD and vertebral pathologies in aging C57BL6 mice that were fed isocaloric diets with standard (dMG+) or reduced amounts of MG derivatives (dMG-; containing 60-70% less dMG). dMG+ mice exhibited a pre-diabetic phenotype, as they were insulin resistant but not hyperglycemic. Vertebrae of dMG+ mice displayed increased cortical-thickness and cortical-area, greater MG-AGE accumulation and ectopic calcification in vertebral endplates. IVD morphology of dMG+ mice exhibited ectopic calcification, hypertrophic differentiation and glycosaminoglycan loss relative to dMG- mice. Overall, chronic exposure to dietary AGEs promoted age-accelerated IVD degeneration and vertebral alterations involving ectopic calcification which occurred in parallel with insulin resistance, and which were prevented with dMG- diet. This study described a new mouse model for diet-induced spinal degeneration, and results were in support of the hypothesis that chronic AGE ingestion could be a factor contributing to a pre-diabetic state, ectopic calcifications in spinal tissues, and musculoskeletal complications that are more generally known to occur with chronic diabetic conditions.

  7. Creatine plays a direct role as a protein modifier in the formation of a novel advanced glycation end product.

    PubMed

    Miyazaki, Kiminori; Nagai, Ryoji; Horiuchi, Seikoh

    2002-10-01

    Pentosidine, a cross-link structure between lysine and arginine residues, is one of the major advanced glycation end products (AGE). It is formed by the reaction of ribose with lysine and arginine. The pentosidine concentration produced by in vitro incubation of plasma obtained from uremic patients was reported to be higher than in normal plasma, indicating that uremic plasma contains an enhancer(s) for pentosidine formation [Miyata, T., Ueda, Y., Yamada, Y., Izuhara, Y., Wada, T., Jadoul, M., Saito, A., Kurokawa, K., and Strihou, C.Y. (1998) J. Am. Soc. Nephrol. 9, 2349-2356]. Since our preliminary study using a monoclonal anti-pentosidine antibody identified creatine as the most effective enhancer, the purpose of the present study was to clarify the mechanism by which creatine contributes to pentosidine formation. Lysine was incubated with ribose in the presence of creatine and analyzed by reverse phase high performance liquid chromatography. A novel fluorescent peak (lambda(ex/em) = 335/385 nm) was detected at 8 min, under conditions at which the authentic pentosidine (lysine was incubated with ribose in the presence of arginine under identical conditions) eluted at 12 min. Structural analyses of this compound revealed a pentosidine-like structure in which the arginine residue was replaced by creatine. This novel AGE-structure, named here creatine-derived pentosidine (C-pentosidine), was detected in the plasma of patients on hemodialysis. These results indicate that creatine increases the formation of C-pentosidine but not authentic pentosidine. This study indicates that creatine plays a direct role as a protein modifier in C-pentosidine formation, although the clinical significance of C-pentosidine is still unknown.

  8. Advanced glycation end products (AGEs) increase human mesangial foam cell formation by increasing Golgi SCAP glycosylation in vitro.

    PubMed

    Yuan, Yang; Zhao, Lei; Chen, Yaxi; Moorhead, John F; Varghese, Zac; Powis, Stephen H; Minogue, Shane; Sun, Zilin; Ruan, Xiong Z

    2011-07-01

    Advanced glycation end products (AGEs) is one of the causative factors of diabetic nephropathy, which is associated with lipid accumulation in glomeruli. This study was designed to investigate whether N(ε)-(carboxymethyl) lysine (CML; a member of the AGEs family) increases lipid accumulation by impairing the function of sterol-regulatory element binding protein (SREBP) cleavage-activating protein (SCAP) in human mesangial cells (HMCs). Intracellular cholesterol content was assessed by Oil Red O staining and quantitative assay. The expression of molecules controlling cholesterol homeostasis was examined using real-time quantitative RT-PCR and Western blotting. The activity of Golgi-processing enzymes was determined using enzyme-based methods, and the translocation of SCAP from the endoplasmic reticulum (ER) to the Golgi was detected by confocal microscopy. CML increased cholesterol accumulation in HMCs. Exposure to CML increased expression and abnormal translocation of SCAP from the ER to the Golgi even in the presence of a high concentration of LDL. The increased SCAP translocation carried more SREBP-2 to the Golgi for activation by proteolytic cleavages, enhancing transcription of 3-hydroxy-3-methylclutaryl-CoA reductase and the LDL receptor. CML increased Golgi mannosidase activity, which may enhance glycosylation of SCAP. This prolonged the half-life and enhanced recycling of SCAP between the ER and the Golgi. The effects of CML were blocked by inhibitors of Golgi mannosidases. AGEs (CML) increased lipid synthesis and uptake, thereby causing foam cell formation via increasing transcription and protein glycosylation of SCAP in HMCs. These data imply that inhibitors of Golgi-processing enzymes might have a potential renoprotective role in prevention of mesangial foam cell formation.

  9. Skin autofluorescence, a measure of cumulative metabolic stress and advanced glycation end products, predicts mortality in hemodialysis patients.

    PubMed

    Meerwaldt, Robbert; Hartog, Jasper W L; Graaff, Reindert; Huisman, Roel J; Links, Thera P; den Hollander, Nynke C; Thorpe, Susan R; Baynes, John W; Navis, Gerjan; Gans, Rijk O B; Smit, Andries J

    2005-12-01

    Tissue advanced glycation end products (AGE) are a measure of cumulative metabolic stress and trigger cytokines driven inflammatory reactions. AGE are thought to contribute to the chronic complications of diabetes and ESRD. Tissue autofluorescence is related to the accumulation of AGE. Therefore, skin autofluorescence (AF) may provide prognostic information on mortality in hemodialysis (HD) patients. Skin AF was measured noninvasively with an AF reader at baseline in 109 HD patients. Overall and cardiovascular mortality was monitored prospectively during a period of 3 yr. The AF reader was validated against AGE contents in skin biopsies from 29 dialysis patients. Forty-two of the 109 (38.5%) HD patients died. Cox regression analysis showed that AF was an independent predictor of overall and cardiovascular mortality (for overall mortality odds ratio [OR] 3.9), as were pre-existing cardiovascular disease (CVD; OR 3.1), C-reactive protein (OR 1.1), and serum albumin (OR 0.3). Multivariate analysis revealed that 65% of the variance in AF could be attributed to the independent effects of age, dialysis and renal failure duration, presence of diabetes, triglycerides levels, and C-reactive protein. AF was also independently linked to the presence of CVD at baseline (OR 8.8; P < 0.001). AF correlated with collagen-linked fluorescence (r = 0.71, P < 0.001), pentosidine (r = 0.75, P < 0.001), and carboxy(m)ethyllysine (both r = 0.45, P < 0.01). Skin AF is a strong and independent predictor of mortality in ESRD. This supports a role for AGE as a contributor to mortality and CVD and warrants interventions specifically aimed at AGE accumulation.

  10. Skin autofluorescence relates to soluble receptor for advanced glycation end-products and albuminuria in diabetes mellitus.

    PubMed

    Skrha, J; Soupal, J; Loni Ekali, G; Prázný, M; Kalousová, M; Kvasnička, J; Landová, L; Zima, T; Skrha, J

    2013-01-01

    The aim of this study was to compare skin autofluorescence caused by advanced glycation end-products (AGEs) with biochemical markers of endothelial dysfunction and soluble receptor for AGEs (sRAGE) in patients with diabetes. Skin autofluorescence (AF) assessed by AGE-Reader was evaluated with sRAGE and other biochemical parameters in 88 patients with diabetes (47 Type 1/T1DM/ and 41 Type 2/T2DM/) and 20 controls. Skin AF was significantly higher in T1DM and T2DM in comparison to controls (2.39 ± 0.54, 2.63 ± 0.73 versus 1.96 ± 0.33 AU; P < 0.0001). Positive correlation of AF with sRAGE was detected in T1DM and T2DM (r = 0.37, P < 0.02 and r = 0.60, P < 0.0001), but not in controls. Significantly higher AF values were found in patients with positive albuminuria as compared to those with normal albuminuria. Similarly, higher AF was detected in patients with endothelial dysfunction expressed by vWF, ICAM-1, and VCAM-1. Multiple regression analysis revealed independent association of skin AF with age, sRAGE, and albumin-creatinine ratio in patients with diabetes (R (2) = 0.38). Our study confirms that AF is elevated in patients with diabetes, especially with positive albuminuria and endothelial dysfunction. The strong and independent relationship between AF and sRAGE supports the idea that AF may reflect AGEs/RAGE interactions. The exact mechanism remains to be established.

  11. Advanced Glycation End Products Inhibit the Proliferation of Human Umbilical Vein Endothelial Cells by Inhibiting Cathepsin D

    PubMed Central

    Li, Yuan; Chang, Ye; Ye, Ning; Dai, Dongxue; Chen, Yintao; Zhang, Naijin; Sun, Guozhe; Sun, Yingxian

    2017-01-01

    We aimed to investigate the effect of advanced glycation end products (AGEs) on the proliferation and migration ability of human umbilical vein endothelial cells (HUVECs). Cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay, real-time cell analyzer and 5-Ethynyl-2′-deoxyuridine (EdU) staining. Cell migration was detected by wound-healing and transwell assay. AGEs significantly inhibited the proliferation and migration of HUVECs in a time-and dose-dependent way. Western blotting revealed that AGEs dramatically increased the expression of microtubule-associated protein 1 light chain 3 (LC3) II/I and p62. Immunofluorescence of p62 and acridine orange staining revealed that AGEs significantly increased the expression of p62 and the accumulation of autophagic vacuoles, respectively. Chloroquine (CQ) could further promote the expression of LC3 II/I and p62, increase the accumulation of autophagic vacuoles and promote cell injury induced by AGEs. In addition, AGEs reduced cathepsin D (CTSD) expression in a time-dependent way. Overexpression of wild-type CTSD significantly decreased the ratio of LC 3 II/I as well as p62 accumulation induced by AGEs, but overexpression of catalytically inactive mutant CTSD had no such effects. Only overexpression of wild-type CTSD could restore the proliferation of HUVECs inhibited by AGEs. However, overexpression of both wild-type CTSD and catalytically inactive mutant CTSD could promote the migration of HUVECs inhibited by AGEs. Collectively, our study found that AGEs inhibited the proliferation and migration in HUVECs and promoted autophagic flux, which in turn played a protective role against AGEs-induced cell injury. CTSD, in need of its catalytic activity, may promote proliferation in AGEs-treated HUVECs independent of the autophagy-lysosome pathway. Meanwhile, CTSD could improve the migration of AGEs-treated HUVECs regardless of its enzymatic activity. PMID:28218663

  12. Chronic Ingestion of Advanced Glycation End Products Induces Degenerative Spinal Changes and Hypertrophy in Aging Pre-Diabetic Mice

    PubMed Central

    Illien-Jünger, Svenja; Lu, Young; Qureshi, Sheeraz A.; Hecht, Andrew C.; Cai, Weijing; Vlassara, Helen; Striker, Gary E.; Iatridis, James C.

    2015-01-01

    Intervertebral disc (IVD) degeneration and pathological spinal changes are major causes of back pain, which is the top cause of global disability. Obese and diabetic individuals are at increased risk for back pain and musculoskeletal complications. Modern diets contain high levels of advanced glycation end products (AGEs), cyto-toxic components which are known contributors to obesity, diabetes and accelerated aging pathologies. There is little information about potential effects of AGE rich diet on spinal pathology, which may be a contributing cause for back pain which is common in obese and diabetic individuals. This study investigated the role of specific AGE precursors (e.g. methylglyoxal-derivatives (MG)) on IVD and vertebral pathologies in aging C57BL6 mice that were fed isocaloric diets with standard (dMG+) or reduced amounts of MG derivatives (dMG-; containing 60-70% less dMG). dMG+ mice exhibited a pre-diabetic phenotype, as they were insulin resistant but not hyperglycemic. Vertebrae of dMG+ mice displayed increased cortical-thickness and cortical-area, greater MG-AGE accumulation and ectopic calcification in vertebral endplates. IVD morphology of dMG+ mice exhibited ectopic calcification, hypertrophic differentiation and glycosaminoglycan loss relative to dMG- mice. Overall, chronic exposure to dietary AGEs promoted age-accelerated IVD degeneration and vertebral alterations involving ectopic calcification which occurred in parallel with insulin resistance, and which were prevented with dMG- diet. This study described a new mouse model for diet-induced spinal degeneration, and results were in support of the hypothesis that chronic AGE ingestion could be a factor contributing to a pre-diabetic state, ectopic calcifications in spinal tissues, and musculoskeletal complications that are more generally known to occur with chronic diabetic conditions. PMID:25668621

  13. The advanced glycation end product-lowering agent ALT-711 is a low-affinity inhibitor of thiamine diphosphokinase.

    PubMed

    Krautwald, Martina; Leech, Dale; Horne, Stacey; Steele, Megan L; Forbes, Josephine; Rahmadi, Anton; Griffith, Renate; Münch, Gerald

    2011-08-01

    Advanced glycation end products (AGEs) are involved in age-related diseases, including the complications of diabetes and chronic renal impairment with arterial stiffening. Alagebrium chloride (ALT-711) is an AGE-lowering agent with beneficial effects in renal structural and functional parameters in diabetes, decreased diabetes-accelerated atherosclerosis, and age-related myocardial stiffening. ALT-711 exhibits a structural homology to thiamine, and it was suggested to interfere with thiamine metabolism. Thiamine is converted to thiamine diphosphate (TDP) by thiamine diphosphokinase (TDPK). TDP is a cofactor for pyruvate dehydrogenase, α-ketoglutarate dehydrogenase and transketolase. A decreased activity of these enzymes due to TDP deficiency results in disorders such as beriberi and Wernicke-Korsakoff syndrome. Therefore, we investigated whether ALT-711 is an inhibitor of TDPK. Molecular modeling studies showed that ALT-711 fits into the thiamine-binding pocket of TDPK, and there are three interactions between the thiazolium ring and the enzyme, as well as parallel stacking between the phenyl ring and the indole ring of Trp222B. Enzyme kinetic experiments also showed that ALT-711 dose-dependently decreased TDPK activity with K(i)s, calculated by different experiments and fitting models ranging from 0.88 to 1.09 mM. Fitting of the kinetic data favored mixed-mode inhibition with a major role for competitive inhibition. In summary, our results suggest that ALT-711 is a low-affinity inhibitor of TDPK, but is unlikely to interfere with thiamine metabolism at therapeutic concentrations. However, when new AGE-crosslink breakers based on thiamine are designed, care should be taken that they do not act as more potent competitive inhibitors than ALT-711.

  14. Advanced glycation end products regulate anabolic and catabolic activities via NLRP3-inflammasome activation in human nucleus pulposus cells.

    PubMed

    Song, Yu; Wang, Yan; Zhang, Yukun; Geng, Wen; Liu, Wei; Gao, Yong; Li, Shuai; Wang, Kun; Wu, Xinghuo; Kang, Liang; Yang, Cao

    2017-02-22

    Intervertebral disc degeneration is widely recognized as a cause of lower back pain, neurological dysfunction and other musculoskeletal disorders. The major inflammatory cytokine IL-1β is associated with intervertebral disc degeneration; however, the molecular mechanisms that drive IL-1β production in the intervertebral disc, especially in nucleus pulposus (NP) cells, are unknown. In some tissues, advanced glycation end products (AGEs), which accumulate in NP tissues and promote its degeneration, increase oxidative stress and IL-1β secretion, resulting in disorders, such as obesity, diabetes mellitus and ageing. It remains unclear whether AGEs exhibit similar effects in NP cells. In this study, we observed significant activation of the NLRP3 inflammasome in NP tissues obtained from patients with degenerative disc disease compared to that with idiopathic scoliosis according to results detected by Western blot and immunofluorescence. Using NP cells established from healthy tissues, our in vitro study revealed that AGEs induced an inflammatory response in NP cells and a degenerative phenotype in a NLRP3-inflammasome-dependent manner related to the receptor for AGEs (RAGE)/NF-κB pathway and mitochondrial damage induced by mitochondrial reactive oxygen species (mtROS) generation, mitochondrial permeability transition pore (mPTP) activation and calcium mobilization. Among these signals, both RAGE and mitochondrial damage primed NLRP3 and pro-IL-1β activation as upstream signals of NF-κB activity, whereas mitochondrial damage was critical for the assembly of inflammasome components. These results revealed that accumulation of AGEs in NP tissue may initiate inflammation-related degeneration of the intervertebral disc via activation of the NLRP3 inflammasome.

  15. Protective effects of physiological testosterone on advanced glycation end product‑induced injury in human endothelial cells.

    PubMed

    Xie, Yaping; Yu, Dan; Wu, Jiahua; Li, Lin

    2017-03-01

    The effect of testosterone, a sex steroid, on endothelial cells is controversial as it is uncertain if it has a protective effect on them. Whether physiological testosterone can inhibit the deleterious effects of advanced glycation end products (AGEs) on endothelial cells remains to be elucidated. The present study focused on elucidating the effect of testosterone on the injury of endothelial cells induced by AGEs. Human umbilical vein endothelial cells (HUVECs) were cultured in vitro and treated with AGEs in the presence or absence of various concentrations of testosterone. The cell viability in each group was measured using an MTS assay. Early‑stage apoptosis was detected using flow cytometry with Annexin V‑fluorescein isothiocyanate/propidium iodide double staining, and the expression levels of apoptosis‑associated proteins, B cell lymphoma‑2 (Bcl‑2), Bcl‑2‑associated X protein (Bax) and caspase‑3, were determined using western blot analysis. Oxidative stress and pro‑inflammatory parameters in the medium were evaluated using an enzyme‑linked immunosorbent assay. The MTS results showed that AGEs significantly decreased the proliferation of HUVECs, whereas a physiological concentration of testosterone alleviated this damage. Physiological concentrations of testosterone protected the HUVECs from AGE‑induced apoptosis, mediated by caspase‑3 and Bax/Bcl‑2. In addition, treatment of the HUVECs with AGEs caused a significant decrease in anti‑oxidative parameters, but increased the concentrations of malondialdehyde and tumor necrosis factor‑α. The activation of Janus kinase 2 and signal transducer and activator of transcription 3 was significantly increased by incubation with AGEs. However, pre‑incubation with a physiological concentration of testosterone attenuated these changes. Therefore, the data obtained in the present study established the potential role of physiological testosterone in ameliorating AGE‑induced damage in

  16. Potential involvement of dietary advanced glycation end products in impairment of skeletal muscle growth and muscle contractile function in mice.

    PubMed

    Egawa, Tatsuro; Tsuda, Satoshi; Goto, Ayumi; Ohno, Yoshitaka; Yokoyama, Shingo; Goto, Katsumasa; Hayashi, Tatsuya

    2017-01-01

    Diets enriched with advanced glycation end products (AGE) have recently been related to muscle dysfunction processes. However, it remains unclear whether long-term exposure to an AGE-enriched diet impacts physiological characteristics of skeletal muscles. Therefore, we explored the differences in skeletal muscle mass, contractile function and molecular responses between mice receiving a diet high in AGE (H-AGE) and low in AGE (L-AGE) for 16 weeks. There were no significant differences between L-AGE and H-AGE mice with regard to body weight, food intake or epididymal fat pad weight. However, extensor digitorum longus (EDL) and plantaris (PLA) muscle weights in H-AGE mice were lower compared with L-AGE mice. Higher levels of N ε -(carboxymethyl)-l-lysine, a marker for AGE, in EDL muscles of H-AGE mice were observed compared with L-AGE mice. H-AGE mice showed lower muscle strength and endurance in vivo and lower muscle force production of PLA muscle in vitro. mRNA expression levels of myogenic factors including myogenic factor 5 and myogenic differentiation in EDL muscle were lower in H-AGE mice compared with L-AGE mice. The phosphorylation status of 70-kDa ribosomal protein S6 kinase Thr389, an indicator of protein synthesis signalling, was lower in EDL muscle of H-AGE mice than that of L-AGE mice. These findings suggest that long-term exposure to an AGE-enriched diet impairs skeletal muscle growth and muscle contractile function, and that these muscle dysfunctions may be attributed to the inhibition of myogenic potential and protein synthesis.

  17. Advanced Glycation End Products Inhibit the Proliferation of Human Umbilical Vein Endothelial Cells by Inhibiting Cathepsin D.

    PubMed

    Li, Yuan; Chang, Ye; Ye, Ning; Dai, Dongxue; Chen, Yintao; Zhang, Naijin; Sun, Guozhe; Sun, Yingxian

    2017-02-17

    We aimed to investigate the effect of advanced glycation end products (AGEs) on the proliferation and migration ability of human umbilical vein endothelial cells (HUVECs). Cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay, real-time cell analyzer and 5-Ethynyl-2'-deoxyuridine (EdU) staining. Cell migration was detected by wound-healing and transwell assay. AGEs significantly inhibited the proliferation and migration of HUVECs in a time-and dose-dependent way. Western blotting revealed that AGEs dramatically increased the expression of microtubule-associated protein 1 light chain 3 (LC3) II/I and p62. Immunofluorescence of p62 and acridine orange staining revealed that AGEs significantly increased the expression of p62 and the accumulation of autophagic vacuoles, respectively. Chloroquine (CQ) could further promote the expression of LC3 II/I and p62, increase the accumulation of autophagic vacuoles and promote cell injury induced by AGEs. In addition, AGEs reduced cathepsin D (CTSD) expression in a time-dependent way. Overexpression of wild-type CTSD significantly decreased the ratio of LC 3 II/I as well as p62 accumulation induced by AGEs, but overexpression of catalytically inactive mutant CTSD had no such effects. Only overexpression of wild-type CTSD could restore the proliferation of HUVECs inhibited by AGEs. However, overexpression of both wild-type CTSD and catalytically inactive mutant CTSD could promote the migration of HUVECs inhibited by AGEs. Collectively, our study found that AGEs inhibited the proliferation and migration in HUVECs and promoted autophagic flux, which in turn played a protective role against AGEs-induced cell injury. CTSD, in need of its catalytic activity, may promote proliferation in AGEs-treated HUVECs independent of the autophagy-lysosome pathway. Meanwhile, CTSD could improve the migration of AGEs-treated HUVECs regardless of its enzymatic activity.

  18. Receptor for advanced glycation end products contributes to postnatal pulmonary development and adult lung maintenance program in mice.

    PubMed

    Fineschi, Silvia; De Cunto, Giovanna; Facchinetti, Fabrizio; Civelli, Maurizio; Imbimbo, Bruno P; Carnini, Chiara; Villetti, Gino; Lunghi, Benedetta; Stochino, Stefania; Gibbons, Deena L; Hayday, Adrian; Lungarella, Giuseppe; Cavarra, Eleonora

    2013-02-01

    The role of the receptor for advanced glycation end products (RAGE) in promoting the inflammatory response through activation of NF-κB pathway is well established. Recent findings indicate that RAGE may also have a regulative function in apoptosis, as well as in cellular proliferation, differentiation, and adhesion. Unlike other organs, lung tissue in adulthood and during organ development shows relatively high levels of RAGE expression. Thus a role for the receptor in lung organogenesis and homeostasis may be proposed. To evaluate the role of RAGE in lung development and adult lung homeostasis, we generated hemizygous and homozygous transgenic mice overexpressing human RAGE, and analyzed their lungs from the fourth postnatal day to adulthood. Moderate RAGE hyperexpression during lung development influenced secondary septation, resulting in an impairment of alveolar morphogenesis and leading to significant changes in morphometric parameters such as airspace number and the size of alveolar ducts. An increase in alveolar cell apoptosis and a decrease in cell proliferation were demonstrated by the terminal deoxy-nucleotidyltransferase-mediated dUTP nick end labeling reaction, active caspase-3, and Ki-67 immunohistochemistry. Alterations in elastin organization and deposition and in TGF-β expression were observed. In homozygous mice, the hyperexpression of RAGE resulted in histological changes resembling those changes characterizing human bronchopulmonary dysplasia (BPD). RAGE hyperexpression in the adult lung is associated with an increase of the alveolar destructive index and persistent inflammatory status leading to "destructive" emphysema. These results suggest an important role for RAGE in both alveolar development and lung homeostasis, and open new doors to working hypotheses on the pathogenesis of BPD and chronic obstructive pulmonary disease.

  19. Pioglitazone inhibits high glucose-induced expression of receptor for advanced glycation end products in coronary artery smooth muscle cells

    PubMed Central

    DI, BEI-BING; LI, HONG-WEI; LI, WEI-PING; SHEN, XU-HUA; SUN, ZHI-JUN; WU, XING

    2015-01-01

    Receptor for advanced glycation end products (RAGE) is critical in inflammatory diseases, including diabetes and atherosclerosis. The mechanism underlying the effect of peroxisome proliferator-activated receptor γ (PPARγ) agonist pioglitazone (PIO) on RAGE expression in coronary artery smooth muscle cells (SMCs) stimulated by high glucose concentrations remains to be elucidated. In the present study, the effect and mechanism of action of PIO on RAGE expression in SMCs was investigated following treatment with high glucose concentrations. Rat coronary artery SMCs were pretreated with PIO alone, PIO and GW9662 (a PPARγ antagonist), diphenyleneiodonium (DPI; a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor) or the antioxidant pyrrolidine dithiocarbamate (PDTC; a nuclear factor-κB (NF-κB) inhibitor), followed by treatment with high glucose. RAGE mRNA and protein expression, reactive oxygen species (ROS) production and NF-κB nuclear translocation were investigated. Glucose induced RAGE expression in a dose-dependent manner, with maximal effect at a concentration of 25 mmol/l following treatment for 48 h. PIO, DPI and PDTC reduced high glucose-induced increases in RAGE protein and mRNA expression. PIO prominently downregulated RAGE expression and inhibited high glucose-induced increases in ROS production and NF-κB activation (P<0.05). Pretreatment with PIO and GW9662 did not exhibit this inhibitory effect. High glucose may stimulate RAGE expression in coronary artery SMCs through NADPH oxidase-mediated ROS generation and NF-κB activation. PIO downregulated RAGE expression and inhibited ROS production and NF-κB activation via PPARγ activation, which may prevent the inflammatory effect of AGE/RAGE system in diabetes. PMID:25523934

  20. Skin Autofluorescence Relates to Soluble Receptor for Advanced Glycation End-Products and Albuminuria in Diabetes Mellitus

    PubMed Central

    Škrha, J.; Šoupal, J.; Loni Ekali, G.; Prázný, M.; Kalousová, M.; Kvasnička, J.; Landová, L.; Zima, T.; Škrha, J.

    2013-01-01

    The aim of this study was to compare skin autofluorescence caused by advanced glycation end-products (AGEs) with biochemical markers of endothelial dysfunction and soluble receptor for AGEs (sRAGE) in patients with diabetes. Skin autofluorescence (AF) assessed by AGE-Reader was evaluated with sRAGE and other biochemical parameters in 88 patients with diabetes (47 Type 1/T1DM/ and 41 Type 2/T2DM/) and 20 controls. Skin AF was significantly higher in T1DM and T2DM in comparison to controls (2.39 ± 0.54, 2.63 ± 0.73 versus 1.96 ± 0.33 AU; P < 0.0001). Positive correlation of AF with sRAGE was detected in T1DM and T2DM (r = 0.37, P < 0.02 and r = 0.60, P < 0.0001), but not in controls. Significantly higher AF values were found in patients with positive albuminuria as compared to those with normal albuminuria. Similarly, higher AF was detected in patients with endothelial dysfunction expressed by vWF, ICAM-1, and VCAM-1. Multiple regression analysis revealed independent association of skin AF with age, sRAGE, and albumin-creatinine ratio in patients with diabetes (R2 = 0.38). Our study confirms that AF is elevated in patients with diabetes, especially with positive albuminuria and endothelial dysfunction. The strong and independent relationship between AF and sRAGE supports the idea that AF may reflect AGEs/RAGE interactions. The exact mechanism remains to be established. PMID:23671885

  1. Dietary advanced glycation end products restriction diminishes inflammation markers and oxidative stress in patients with type 2 diabetes mellitus

    PubMed Central

    Luévano-Contreras, Claudia; Garay-Sevilla, Ma. Eugenia; Wrobel, Kazimierz; Malacara, Juan M.; Wrobel, Katarzyna

    2013-01-01

    The augmented consumption of dietary advanced glycation end products (dAGEs) has been associated with increased oxidative stress and inflammation, however, there is insufficient information over the effect on insulin resistance. The objective of the present study is to investigate the effect of dAGEs restriction on tumor necrosis factor-α (TNF-α), malondialdehyde, C-reactive protein (CRP), and insulin resistance in DM2 patients. We carried out a randomized 6 weeks prospective study in two groups of patients: subjects with a standard diet (n = 13), vs low dAGEs (n = 13). At the beginning and the end of study, we collected anthropometric measurements, and values of circulating glucose, HbA1c, lipids, insulin, serum AGEs, CRP, TNF-α and malondialdehyde. Anthropometric measurements, glucose, and lipids were similar in both groups at base line and at the end of the study. Estimation of basal dAGEs was similar in both groups; after 6 weeks it was unchanged in the standard group but in the low dAGEs group decreased by 44% (p<0.0002). Changes in TNF-α levels were different under standard diet (12.5 ± 14.7) as compared with low dAGEs (−18.36 ± 17.1, p<0.00001); changes in malondialdehyde were different in the respective groups (2.0 ± 2.61 and −0.83 ± 2.0, p<0.005) no changes were found for insulin levels or HOMA-IR. In conclusion, The dAGEs restriction decreased significantly TNF-α and malondialdehyde levels. PMID:23341693

  2. IN SITU ACCUMULATION OF ADVANCED GLYCATION ENDPRODUCTS (AGES) IN BONE MATRIX AND ITS CORRELATION WITH OSTEOCLASTIC BONE RESORPTION

    PubMed Central

    Dong, X. Neil; Qin, An; Xu, Jiake; Wang, Xiaodu

    2011-01-01

    Advanced glycation end products (AGEs) have been observed to accumulate in bone with increasing age and may impose effects on bone resorption activities. However, the underlying mechanism of AGEs accumulation in bone is still poorly understood. In this study, human cortical bone specimens from young (31±6 years old), middle-aged (51±3 years old) and elderly (76±4 years old) groups were examined to determine the spatial-temporal distribution of AGEs in bone matrix and its effect on bone resorption activities by directly culturing osteoclastic cells on bone slices. The results of this study indicated that the fluorescence intensity (excitation wave length 360 nm and emission wave length 470±40 nm) could be used to estimate the relative distribution of AGEs in bone (pentosidine as its marker) under an epifluorescence microscope. Using the fluorescence intensity as the relative measure of AGEs concentration, it was found that the concentration of AGEs varied with biological tissue ages, showing the greatest amount in the interstitial tissue, followed by the old osteons, and the least amount in newly formed osteons. In addition, AGEs accumulation was found to be dependent on donor ages, suggesting that the younger the donor the less AGEs were accumulated in the tissue. Most interestingly, AGEs accumulation appeared to initiate from the region of cement lines, and spread diffusively to the other parts as the tissue aged. Finally, it was observed that the bone resorption activities of osteoclasts were positively correlated with the in situ concentration of AGEs and such an effect was enhanced with increasing donor age. These findings may help elucidate the mechanism of AGEs accumulation in bone and its association with bone remodeling process. PMID:21530698

  3. Advanced Glycation End-Products Reduce Collagen Molecular Sliding to Affect Collagen Fibril Damage Mechanisms but Not Stiffness

    PubMed Central

    Fessel, Gion; Li, Yufei; Diederich, Vincent; Guizar-Sicairos, Manuel; Schneider, Philipp; Sell, David R.; Monnier, Vincent M.; Snedeker, Jess G.

    2014-01-01

    Advanced glycation end-products (AGE) contribute to age-related connective tissue damage and functional deficit. The documented association between AGE formation on collagens and the correlated progressive stiffening of tissues has widely been presumed causative, despite the lack of mechanistic understanding. The present study investigates precisely how AGEs affect mechanical function of the collagen fibril – the supramolecular functional load-bearing unit within most tissues. We employed synchrotron small-angle X-ray scattering (SAXS) and carefully controlled mechanical testing after introducing AGEs in explants of rat-tail tendon using the metabolite methylglyoxal (MGO). Mass spectrometry and collagen fluorescence verified substantial formation of AGEs by the treatment. Associated mechanical changes of the tissue (increased stiffness and failure strength, decreased stress relaxation) were consistent with reports from the literature. SAXS analysis revealed clear changes in molecular deformation within MGO treated fibrils. Underlying the associated increase in tissue strength, we infer from the data that MGO modified collagen fibrils supported higher loads to failure by maintaining an intact quarter-staggered conformation to nearly twice the level of fibril strain in controls. This apparent increase in fibril failure resistance was characterized by reduced side-by-side sliding of collagen molecules within fibrils, reflecting lateral molecular interconnectivity by AGEs. Surprisingly, no change in maximum fibril modulus (2.5 GPa) accompanied the changes in fibril failure behavior, strongly contradicting the widespread assumption that tissue stiffening in ageing and diabetes is directly related to AGE increased fibril stiffness. We conclude that AGEs can alter physiologically relevant failure behavior of collagen fibrils, but that tissue level changes in stiffness likely occur at higher levels of tissue architecture. PMID:25364829

  4. Protective effects of physiological testosterone on advanced glycation end product-induced injury in human endothelial cells

    PubMed Central

    Xie, Yaping; Yu, Dan; Wu, Jiahua; Li, Lin

    2017-01-01

    The effect of testosterone, a sex steroid, on endothelial cells is controversial as it is uncertain if it has a protective effect on them. Whether physiological testosterone can inhibit the deleterious effects of advanced glycation end products (AGEs) on endothelial cells remains to be elucidated. The present study focused on elucidating the effect of testosterone on the injury of endothelial cells induced by AGEs. Human umbilical vein endothelial cells (HUVECs) were cultured in vitro and treated with AGEs in the presence or absence of various concentrations of testosterone. The cell viability in each group was measured using an MTS assay. Early-stage apoptosis was detected using flow cytometry with Annexin V-fluorescein isothiocyanate/propidium iodide double staining, and the expression levels of apoptosis-associated proteins, B cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax) and caspase-3, were determined using western blot analysis. Oxidative stress and pro-inflammatory parameters in the medium were evaluated using an enzyme-linked immunosorbent assay. The MTS results showed that AGEs significantly decreased the proliferation of HUVECs, whereas a physiological concentration of testosterone alleviated this damage. Physiological concentrations of testosterone protected the HUVECs from AGE-induced apoptosis, mediated by caspase-3 and Bax/Bcl-2. In addition, treatment of the HUVECs with AGEs caused a significant decrease in anti-oxidative parameters, but increased the concentrations of malondialdehyde and tumor necrosis factor-α. The activation of Janus kinase 2 and signal transducer and activator of transcription 3 was significantly increased by incubation with AGEs. However, pre-incubation with a physiological concentration of testosterone attenuated these changes. Therefore, the data obtained in the present study established the potential role of physiological testosterone in ameliorating AGE-induced damage in HUVECs. PMID:28112379

  5. Generation of Soluble Advanced Glycation End Products Receptor (sRAGE)-Binding Ligands during Extensive Heat Treatment of Whey Protein/Lactose Mixtures Is Dependent on Glycation and Aggregation.

    PubMed

    Liu, Fahui; Teodorowicz, Małgorzata; Wichers, Harry J; van Boekel, Martinus A J S; Hettinga, Kasper A

    2016-08-24

    Heating of protein- and sugar-containing materials is considered the primary factor affecting the formation of advanced glycation end products (AGEs). This study aimed to investigate the influence of heating conditions, digestion, and aggregation on the binding capacity of AGEs to the soluble AGE receptor (sRAGE). Samples consisting of mixtures of whey protein and lactose were heated at 130 °C. An in vitro infant digestion model was used to study the influence of heat treatment on the digestibility of whey proteins. The amount of sRAGE-binding ligands before and after digestion was measured by an ELISA-based sRAGE-binding assay. Water activity did not significantly affect the extent of digestibility of whey proteins dry heated at pH 5 (ranging from 3.3 ± 0.2 to 3.6 ± 0.1% for gastric digestion and from 53.5 ± 1.5 to 64.7 ± 1.1% for duodenal digestion), but there were differences in cleavage patterns of peptides among the samples heated at different pH values. Formation of sRAGE-binding ligands depended on the formation of aggregates and was limited in the samples heated at pH 5. Moreover, the sRAGE-binding activity of digested sample was changed by protease degradation and correlated with the digestibility of samples. In conclusion, generation of sRAGE-binding ligands during extensive heat treatment of whey protein/lactose mixtures is limited in acidic heating condition and dependent on glycation and aggregation.

  6. Inhibitory effect of vanillic acid on methylglyoxal-mediated glycation in apoptotic Neuro-2A cells.

    PubMed

    Huang, Shang-Ming; Hsu, Chin-Lin; Chuang, Hong-Chih; Shih, Ping-Hsiao; Wu, Chi-Hao; Yen, Gow-Chin

    2008-11-01

    Methylglyoxal is a reactive dicarbonyl compound generated as an intermediate of glycolysis during the physical glycation in the diabetic condition. It is considered to be a potent precursor of advanced glycation end products (AGEs) formation. Methylglyoxal itself and methylglyoxal-derived AGEs have been commonly implicated in the development of diabetic neuropathy. Our previous study indicated that vanillic acid showed an inhibitory effect against methylglyoxal-mediated Neuro-2A cell apoptosis, suggesting that vanillic acid might possess cytoprotective properties in the prevention of diabetic neuropathy complication. In this study, the effects of vanillic acid on the methylglyoxal-mediated glycation system involved in the progression of Neuro-2A cell apoptosis were further investigated. Our findings indicated that methylglyoxal-induced Neuro-2A cell apoptosis was mediated through the possible glycation mechanism of oxidative stress, activation of the MAPK signaling pathway (p38 and JNK) and oxidation-sensitive protein expression (PKC and p47(phox)) and methylglyoxal-derived N-epsilon-(carboxymethyl)lysine (CML) formation. Vanillic acid, however, suppressed methylglyoxal-induced Neuro-2A cell apoptosis via inhibition of glycation mechanisms including ROS, p38 and JNK, PKC and p47(phox), and methylglyoxal-derived CML formation. In the present study, we established the first evidence that vanillic acid might contribute to the prevention of the development of diabetic neuropathy by blocking the methylglyoxal-mediated intracellular glycation system.

  7. Interaction between Advanced Glycation End Products Formation and Vascular Responses in Femoral and Coronary Arteries from Exercised Diabetic Rats

    PubMed Central

    Delbin, Maria A.; Davel, Ana Paula C.; Couto, Gisele Kruger; de Araújo, Gustavo G.; Rossoni, Luciana Venturini; Antunes, Edson; Zanesco, Angelina

    2012-01-01

    Background The majority of studies have investigated the effect of exercise training (TR) on vascular responses in diabetic animals (DB), but none evaluated nitric oxide (NO) and advanced glycation end products (AGEs) formation associated with oxidant and antioxidant activities in femoral and coronary arteries from trained diabetic rats. Our hypothesis was that 8-week TR would alter AGEs levels in type 1 diabetic rats ameliorating vascular responsiveness. Methodology/Principal Findings Male Wistar rats were divided into control sedentary (C/SD), sedentary diabetic (SD/DB), and trained diabetic (TR/DB). DB was induced by streptozotocin (i.p.: 60 mg/kg). TR was performed for 60 min per day, 5 days/week, during 8 weeks. Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP), phenylephrine (PHE) and tromboxane analog (U46619) were obtained. The protein expressions of eNOS, receptor for AGEs (RAGE), Cu/Zn-SOD and Mn-SOD were analyzed. Tissues NO production and reactive oxygen species (ROS) generation were evaluated. Plasma nitrate/nitrite (NOx−), superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive substances (TBARS) and Nε-(carboxymethyl) lysine (CML, AGE biomarker). A rightward shift in the concentration-response curves to ACh was observed in femoral and coronary arteries from SD/DB that was accompanied by an increase in TBARS and CML levels. Decreased in the eNOS expression, tissues NO production and NOx− levels were associated with increased ROS generation. A positive interaction between the beneficial effect of TR on the relaxing responses to ACh and the reduction in TBARS and CML levels were observed without changing in antioxidant activities. The eNOS protein expression, tissues NO production and ROS generation were fully re-established in TR/DB, but plasma NOx− levels were partially restored. Conclusion Shear stress induced by TR fully restores the eNOS/NO pathway in both preparations from non-treated diabetic

  8. A Comparative Study on Skin and Plasma Advanced Glycation End Products and Their Associations with Arterial Stiffness

    PubMed Central

    Liu, Chang-Yuan; Huang, Qi-Fang; Cheng, Yi-Bang; Guo, Qian-Hui; Chen, Qi; Li, Yan; Wang, Ji-Guang

    2017-01-01

    Background We compared skin and plasma measurements of advanced glycation end products (AGEs), with particular focus on their levels in the presence of hypertension or diabetes and prediabetes and their associations with arterial stiffness in outpatients with suspected or diagnosed hypertension. Methods Skin AGE accumulation was measured as autofluorescence on the left forearm using the skin autofluorescence Reader and expressed in arbitrary units in the range from 0 to 25. Plasma AGE concentration was measured by the enzyme-linked immunosorbent assay method and logarithmically transformed for statistical analysis. Arterial stiffness was assessed by carotid-femoral pulse wave velocity (cfPWV) using the SphygmoCor system (Sydney, Australia). Results The 218 participants (96 [44.0%] men, mean age 51.9 years) had a mean skin autofluorescence of 1.89 arbitrary units, plasma AGE concentration of 4.47 μg/ml, and cfPWV of 8.0 m/s. Skin autofluorescence was significantly correlated with plasma AGEs in diabetic or prediabetic patients (n = 31, r = 0.37, p = 0.04) but not in subjects with normoglycemia (n = 187, r = −0.05, p = 0.48). Nonetheless, both measurements were significantly (p ≤ 0.001) higher in men (2.00 arbitrary units and 6.73 μg/ml, respectively) than women (1.81 arbitrary units and 3.60 μg/ml, respectively) and in diabetic or prediabetic (2.03 arbitrary units and 6.61 μg/ml, respectively) than normoglycemia subjects (1.87 arbitrary units and 4.17 μg/ml, respectively), but similar in hypertensive (n = 105) and normotensive subjects (n = 113, p ≥ 0.35). In adjusted multiple regression analyses, plasma AGE concentration, but not skin autofluorescence (p ≥ 0.37), was significantly associated with cfPWV in all subjects (β 0.44 m/s for each 10-fold increase; p = 0.04) and in subgroups of men and diabetes and prediabetes (β 0.12-0.55 m/s for each 10-fold increase; p ≤ 0.02). Conclusions Although skin and plasma AGEs were similarly associated with

  9. PF-04494700, an Oral Inhibitor of Receptor For Advanced Glycation End Products (RAGE), in Alzheimer’s disease

    PubMed Central

    Sabbagh, Marwan N.; Agro, Albert; Bell, Joanne; Aisen, Paul S.; Schweizer, Edward; Galasko, Douglas

    2012-01-01

    Objective To evaluate the safety and tolerability of PF-04494700, an oral Inhibitor of receptor for advanced glycation end products (RAGE), in subjects with mild-to-moderate dementia of the Alzheimer’s type. Methods Subjects 50 years and older who met NINCDS-ADRDA criteria for AD with an MMSE score between 12–26 (inclusive) were randomized to 10-weeks of double-blind treatment with either a 10 mg “low dose” of PF-04494700 (after a 6-day loading dose of 30 mg/d to); or a 20 mg “high dose” of PF-04494700 (after a loading dose of 60 mg/d); or placebo. Safety measures included adverse events, laboratory tests, vital signs, and 12-lead ECG. Results 27 subjects received PF-04494700 30/10 mg (female, 63%; mean age, 74.6 years; mean MMSE, 21.1), 28 subjects received PF-04494700 60/20 mg (female, 57%; mean age, 76.6 years; mean MMSE, 21.6), and 12 subjects received placebo (female, 67%; mean age, 74.1 years; mean MMSE, 19.2). A higher proportion of subjects completed 10 weeks of double-blind treatment on both the “low dose” regimen of PF-04494700 (88.9%) and the “high dose” regimen (85.7%) than completed on placebo (66.7%). Discontinuation due to adverse events, and incidence of severe adverse events, respectively, were lower on the “low dose” regimen (7.4%,11.1%) and the “high dose” regimen (3.6%,10.7%) compared to placebo (25.0%,16.7%). There were no clinically meaningful differences in vital signs, laboratory test results, or mean ECG parameters in subjects treated with PF-04494700. PF-04494700 had no consistent effect on plasma levels of Aβ, inflammatory biomarkers, or secondary cognitive outcomes. Conclusions Ten weeks of treatment with PF-04494700 was safe and well-tolerated in subjects with mild-to-moderate AD, indicating the feasibility of a larger long-term efficacy trial. PMID:21192237

  10. Increased receptor for advanced glycation end product expression in the human alcoholic prefrontal cortex is linked to adolescent drinking.

    PubMed

    Vetreno, Ryan P; Qin, Liya; Crews, Fulton T

    2013-11-01

    Adolescence is characterized behaviorally by increased impulsivity and risk-taking that declines in parallel with maturation of the prefrontal cortex and executive function. In the brain, the receptor for advanced glycation end products (RAGE) is critically involved in neurodevelopment and neuropathology. In humans, the risk of alcoholism is greatly increased in those who begin drinking between 13 and 15years of age, and adolescents binge drink more than any other age group. We have previously found that alcoholism is associated with increased expression of neuroimmune genes. This manuscript tested the hypothesis that adolescent binge drinking upregulates RAGE and Toll-like receptor (TLR) 4 as well as their endogenous agonist, high-mobility group box 1 (HMGB1). Immunohistochemistry, Western blot, and mRNA analyses found that RAGE expression was increased in the human post-mortem alcoholic orbitofrontal cortex (OFC). Further, an earlier age of drinking onset correlated with increased expression of RAGE, TLR4, and HMGB1. To determine if alcohol contributed to these changes, we used an adolescent binge ethanol model in rats (5.0g/kg, i.g., 2-day on/2-day off from postnatal day [P] 25 to P55) and assessed neuroimmune gene expression. We found an age-associated decline of RAGE expression from late adolescence (P56) to young adulthood (P80). Adolescent intermittent ethanol exposure did not alter RAGE expression at P56, but increased RAGE in the young adult PFC (P80). Adolescent intermittent ethanol exposure also increased TLR4 and HMGB1 expression at P56 that persisted into young adulthood (P80). Assessment of young adult frontal cortex mRNA (RT-PCR) found increased expression of proinflammatory cytokines, oxidases, and neuroimmune agonists at P80, 25days after ethanol treatment. Together, these human and animal data support the hypothesis that an early age of drinking onset upregulates RAGE/TLR4-HMGB1 and other neuroimmune genes that persist into young adulthood and

  11. Increased Receptor for Advanced Glycation End Product Expression in the Human Alcoholic Prefrontal Cortex is Linked to Adolescent Drinking

    PubMed Central

    Vetreno, Ryan P.; Qin, Liya; Crews, Fulton T.

    2013-01-01

    Adolescence is characterized behaviorally by increased impulsivity and risk-taking that declines in parallel with maturation of the prefrontal cortex and executive function. In the brain, the receptor for advanced glycation end products (RAGE) is critically involved in neurodevelopment and neuropathology. In humans, the risk of alcoholism is greatly increased in those who begin drinking between 13 and 15 years of age, and adolescents binge drink more than any other age group. We have previously found that alcoholism is associated with increased expression of neuroimmune genes. This manuscript tested the hypothesis that adolescent binge drinking upregulates RAGE and Toll-like receptor (TLR) 4 as well as their endogenous agonist, high-mobility group box 1 (HMGB1). Immunohistochemistry, Western blot, and mRNA analyses found that RAGE expression was increased in the human post-mortem alcoholic orbitofrontal cortex (OFC). Further, an earlier age of drinking onset correlated with increased expression of RAGE, TLR4, and HMGB1. To determine if alcohol contributed to these changes, we used an adolescent binge ethanol model in rats (5.0 g/kg, i.g., 2-day on/2-day off from postnatal day [P] 25 to P55) and assessed neuroimmune gene expression. We found an age-associated decline of RAGE expression from late adolescence (P56) to young adulthood (P80). Adolescent intermittent ethanol exposure did not alter RAGE expression at P56, but increased RAGE in the young adult PFC (P80). Adolescent intermittent ethanol exposure also increased TLR4 and HMGB1 expression at P56 that persisted into young adulthood (P80). Assessment of young adult frontal cortex mRNA (RT-PCR) found increased expression of proinflammatory cytokines, oxidases, and neuroimmune agonists at P80, 25 days after ethanol treatment. Together, these human and animal data support the hypothesis that an early age of drinking onset upregulates RAGE/TLR4-HMGB1 and other neuroimmune genes that persist into young adulthood and

  12. The false alarm hypothesis: Food allergy is associated with high dietary advanced glycation end-products and proglycating dietary sugars that mimic alarmins.

    PubMed

    Smith, Peter K; Masilamani, Madhan; Li, Xiu-Min; Sampson, Hugh A

    2017-02-01

    The incidence of food allergy has increased dramatically in the last few decades in westernized developed countries. We propose that the Western lifestyle and diet promote innate danger signals and immune responses through production of "alarmins." Alarmins are endogenous molecules secreted from cells undergoing nonprogrammed cell death that signal tissue and cell damage. High molecular group S (HMGB1) is a major alarmin that binds to the receptor for advanced glycation end-products (RAGE). Advanced glycation end-products (AGEs) are also present in foods. We propose the "false alarm" hypothesis, in which AGEs that are present in or formed from the food in our diet are predisposing to food allergy. The Western diet is high in AGEs, which are derived from cooked meat, oils, and cheese. AGEs are also formed in the presence of a high concentration of sugars. We propose that a diet high in AGEs and AGE-forming sugars results in misinterpretation of a threat from dietary allergens, promoting the development of food allergy. AGEs and other alarmins inadvertently prime innate signaling through multiple mechanisms, resulting in the development of allergic phenotypes. Current hypotheses and models of food allergy do not adequately explain the dramatic increase in food allergy in Western countries. Dietary AGEs and AGE-forming sugars might be the missing link, a hypothesis supported by a number of convincing epidemiologic and experimental observations, as discussed in this article.

  13. p-Dimethylaminobenzaldehyde-reactive substances in tail tendon collagen of streptozotocin-diabetic rats: temporal relation to biomechanical properties and advanced glycation endproduct (AGE)-related fluorescence.

    PubMed

    Stefek, M; Gajdosik, A; Gajdosikova, A; Krizanova, L

    2000-11-15

    In the present work, pepsin digests of tail tendons from streptozotocin-diabetic rats were found to contain material that reacted rapidly at room temperature with p-dimethylaminobenzaldehyde (Ehrlich's reagent) to give an adduct with an absorbance spectrum characteristic of the Ehrlich chromogen of pyrrolic nature determined in ageing collagens. A significant correlation of the Ehrlich adduct with tendon mechanical strength and collagen fluorescence characteristic of advanced glycation endproducts was observed. Collagen content of the Ehrlich-positive material was found to be significantly elevated in tendons of diabetic rats compared with age-matched healthy controls. The results indicate that the p-dimethylaminobenzaldehyde-reactive pyrrole moieties may contribute to the increased cross-linking of diabetic matrix collagen. Profound inhibitory effect of aminoguanidine was observed, underlining the role of non-enzymatic mechanisms of advanced glycation in pyrrolisation and cross-linking of collagen exposed to hyperglycaemia. It is hypothesised that quantification of the p-dimethylaminobenzaldehyde-reactive material in matrix collagen may provide a tissue measure of integrated hyperglycaemia over prolonged periods of time. Further research is to assess the significance of p-dimethylaminobenzaldehyde-reactive substances in diabetic collagen tissues and to reveal their relationship to enzyme-mediated physiological pyrrolisation of ageing collagens.

  14. Evaluating the extent of protein damage in dairy products: simultaneous determination of early and advanced glycation-induced lysine modifications.

    PubMed

    Hegele, Jörg; Parisod, Véronique; Richoz, Janique; Förster, Anke; Maurer, Sarah; Krause, René; Henle, Thomas; Bütler, Timo; Delatour, Thierry

    2008-04-01

    An isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine lysine (Lys), N(epsilon)-fructosyllysine (FL), N epsilon-carboxymethyllysine (CML), and pyrraline (Pyr) in dairy products. The presented approach entails protein cleavage via enzymatic digestion to liberate the aforementioned compounds, which were then quantified using a stable isotope dilution assay. LC-MS/MS analysis was performed by positive electrospray ionization recording two transition reactions per analyte in selected reaction monitoring mode. The CML and Lys values obtained with enzymatic digestion were compared to those acquired with acid hydrolysis HCl (6 mol/L), and the two proteolysis methods yielded comparable quantifications. Allowing for the fact that the investigated compounds are formed during different stages of the glycation process, the method is able to reveal the progress of protein glycation in dairy products.

  15. Methylglyoxal mediated conformational changes in histone H2A-generation of carboxyethylated advanced glycation end products.

    PubMed

    Mir, Abdul Rouf; uddin, Moin; Alam, Khursheed; Ali, Asif

    2014-08-01

    Methylglyoxal, an oxo-aldehyde has been implicated as a potential precursor in non enzymatic glycation reactions. Its role in the modification of extra cellular proteins has been extensively reported, but little is known about its modification of nuclear proteins, like histones. Here, we report the methylglyoxal induced modification of histone H2A which forms an essential part of intact core nucleosome. In this study commercially available histone H2A was subjected to in vitro non-enzymatic glycation by methylglyoxal. The structural alterations in the histone were characterised by various biophysical and biochemical techniques. The modified histone showed hyperchromicity at 276nm, loss in intrinsic tyrosine fluorescence intensity at 305nm along with a red shift, cross linking and dimer formation in SDS PAGE, induction of α-helix in CD spectroscopy, reduced hydrophobicity in ANS binding studies, accumulation of AGE products, increased carbonyl content, and appearance of a novel peak showing carboxyethylation complemented by a shift in amide I and amide II bands in ATR-FTIR spectroscopy. The modified histone exhibited increased melting temperatures (Tm) and enhanced heat capacities (Cp) in differential scanning calorimetric analysis. The results suggest that methylglyoxal significantly altered the structure of the nuclear histone H2A by non enzymatic glycation reaction. The conformational changes in histone H2A may influence the chromatin integrity which may have implications in various pathological conditions.

  16. Vitamin D Levels Decline with Rising Number of Cardiometabolic Risk Factors in Healthy Adults: Association with Adipokines, Inflammation, Oxidative Stress and Advanced Glycation Markers

    PubMed Central

    Krivošíková, Zora; Gajdoš, Martin; Šebeková, Katarína

    2015-01-01

    Introduction Hypovitaminosis D associates with obesity, insulin resistance, hypertension, and dyslipoproteinemia. We asked whether the presence of multiple cardiometabolic risk factors, and which particular combination, exerts additive negative effects on 25(OH)D3 levels; and whether 25(OH)D3 levels associate with markers of inflammation and oxidative stress. Subjects and Methods In non-diabetic medication-free adults central obesity (waist-to-height ratio > 0.5); elevated blood pressure (systolic BP≥130 mm Hg and/or diastolic BP ≥85 mm Hg); increased atherogenic risk (log(TAG/HDL) ≥ 0.11); and insulin resistance (QUICKI < 0.322) were considered as cardiometabolic risk factors. 25(OH)D3 status was classified as deficiency (25(OH)D3 ≤20 ng/ml); insufficiency (levels between 20-to-30 ng/ml), or as satisfactory (>30 ng/ml). Plasma adipokines, inflammatory and oxidative stress markers, advanced glycation end-products, and their soluble receptor were determined. Results 162 subjects were cardiometabolic risk factors-free, 162 presented increased (i.e. 1 or 2), and 87 high number (i.e. 3 or 4) of cardiometabolic risk factors. Mean 25(OH)D3 decreased with rising number of manifested risk factors (36 ± 14 ng/ml, 33 ± 14 ng/ml, and 31 ± 15 ng/ml, respectively; pANOVA: 0.010), while prevalence of hypovitaminosis D did not differ significantly. Elevated blood pressure and insulin resistance appeared as significant determinants of hypovitaminosis D. Subjects presenting these risk factors concurrently displayed the lowest 25(OH)D3 levels (29 ± 15 ng/ml). Plasma adipokines, inflammatory and oxidative stress markers, advanced glycation end-products, and their soluble receptor generally differed significantly between the groups, but only advanced oxidation protein products and advanced glycation end-products associated fluorescence of plasma showed significant independent association with 25(OH)D3 levels. Conclusion In apparently healthy adults increasing number of

  17. Guarana (Paullinia cupana Mart.) prevents β-amyloid aggregation, generation of advanced glycation-end products (AGEs), and acrolein-induced cytotoxicity on human neuronal-like cells.

    PubMed

    Bittencourt, Leonardo da Silva; Zeidán-Chuliá, Fares; Yatsu, Francini Kiyono Jorge; Schnorr, Carlos Eduardo; Moresco, Karla Suzana; Kolling, Eduardo Antônio; Gelain, Daniel Pens; Bassani, Valquiria Linck; Moreira, José Cláudio Fonseca

    2014-11-01

    Advanced glycation end-products (AGEs) are considered potent molecules capable of promoting neuronal cell death and participating in the development of neurodegenerative disorders such as Alzheimer's disease (AD). Previous studies have shown that AGEs exacerbate β-amyloid (Aβ) aggregation and AGE-related cross-links are also detected in senile plaques. Acrolein (ACR) is an α, β-unsaturated aldehyde found in the environment and thermally processed foods, which can additionally be generated through endogenous metabolism. The role of ACR in AD is widely accepted in the literature. Guarana (Paullinia cupana Mart.) is popularly consumed by the population in Brazil, mainly for its stimulant activity. In the present study, we showed that guarana (10, 100, and 1000 µg/mL) is able to prevent protein glycation, β-amyloid aggregation, in vitro methylglyoxal, glyoxal, and ACR (20 μM)-induced toxicity on neuronal-like cells (SH-SY5Y). Since these are considered typical AD pathological hallmarks, we propose that guarana may deserve further research as a potential therapeutic agent in such a neurodegenerative disease.

  18. Effect of PKC-β Signaling Pathway on Expression of MCP-1 and VCAM-1 in Different Cell Models in Response to Advanced Glycation End Products (AGEs).

    PubMed

    Rempel, Lisienny C T; Finco, Alessandra B; Maciel, Rayana A P; Bosquetti, Bruna; Alvarenga, Larissa M; Souza, Wesley M; Pecoits-Filho, Roberto; Stinghen, Andréa E M

    2015-05-14

    Advanced glycation end products (AGEs) are compounds classified as uremic toxins in patients with chronic kidney disease that have several pro-inflammatory effects and are implicated in the development of cardiovascular diseases. To explore the mechanisms of AGEs-endothelium interactions through the receptor for AGEs (RAGE) in the PKC-β pathway, we evaluated the production of MCP-1 and VCAM-1 in human endothelial cells (HUVECs), monocytes, and a coculture of both. AGEs were prepared by albumin glycation and characterized by absorbance and electrophoresis. The effect of AGEs on cell viability was assessed with an MTT assay. The cells were also treated with AGEs with and without a PKC-β inhibitor. MCP-1 and VCAM-1 in the cell supernatants were estimated by ELISA, and RAGE was evaluated by immunocytochemistry. AGEs exposure did not affect cell viability, but AGEs induced RAGE, MCP-1, and VCAM-1 expression in HUVECs. When HUVECs or monocytes were incubated with AGEs and a PKC-β inhibitor, MCP-1 and VCAM-1 expression significantly decreased. However, in the coculture, exposure to AGEs and a PKC-β inhibitor produced no significant effect. This study demonstrates, in vitro, the regulatory mechanisms involved in MCP-1 production in three cellular models and VCAM-1 production in HUVECs, and thus mimics the endothelial dysfunction caused by AGEs in early atherosclerosis. Such mechanisms could serve as therapeutic targets to reduce the harmful effects of AGEs in patients with chronic kidney disease.

  19. Plasma Proteins Modified by Advanced Glycation End Products (AGEs) Reveal Site-specific Susceptibilities to Glycemic Control in Patients with Type 2 Diabetes.

    PubMed

    Greifenhagen, Uta; Frolov, Andrej; Blüher, Matthias; Hoffmann, Ralf

    2016-04-29

    Protein glycation refers to the reversible reaction between aldoses (or ketoses) and amino groups yielding relatively stable Amadori (or Heyns) products. Consecutive oxidative cleavage reactions of these products or the reaction of amino groups with other reactive substances (e.g. α-dicarbonyls) yield advanced glycation end products (AGEs) that can alter the structures and functions of proteins. AGEs have been identified in all organisms, and their contents appear to rise with some diseases, such as diabetes and obesity. Here, we report a pilot study using highly sensitive and specific proteomics approach to identify and quantify AGE modification sites in plasma proteins by reversed phase HPLC mass spectrometry in tryptic plasma digests. In total, 19 AGE modification sites corresponding to 11 proteins were identified in patients with type 2 diabetes mellitus under poor glycemic control. The modification degrees of 15 modification sites did not differ among cohorts of normoglycemic lean or obese and type 2 diabetes mellitus patients under good and poor glycemic control. The contents of two amide-AGEs in human serum albumin and apolipoprotein A-II were significantly higher in patients with poor glycemic control, although the plasma levels of both proteins were similar among all plasma samples. These two modification sites might be useful to predict long term, AGE-related complications in diabetic patients, such as impaired vision, increased arterial stiffness, or decreased kidney function.

  20. Accumulation of the advanced glycation end product carboxymethyl lysine in breast cancer is positively associated with estrogen receptor expression and unfavorable prognosis in estrogen receptor-negative cases.

    PubMed

    Nass, Norbert; Ignatov, Atanas; Andreas, Ludwig; Weißenborn, Christine; Kalinski, Thomas; Sel, Saadettin

    2016-12-23

    Advanced glycation end products (AGEs) accumulate as a result of high concentrations of reactive aldehydes, oxidative stress, and insufficient degradation of glycated proteins. AGEs are therefore accepted biomarkers for aging, diabetes, and several degenerative diseases. Due to the Warburg effect and increased oxidative stress, cancer cells frequently accumulate significant amounts of AGEs. As the accumulation of AGEs may reflect the metabolic state and receptor signaling, we evaluated the potential prognostic and predictive value of this biomarker. We used immunohistochemistry to determine the AGE Nε-carboxymethyl lysine (CML) in 213 mammary carcinoma samples and Western blotting to detect AGEs in cell cultures. Whereas no significant correlation between hormone receptor status and CML was observed in cell lines, CML accumulation in tumors was positively correlated with the presence of estrogen receptor alpha, the postmenopausal state, and age. A negative correlation was found for grade III carcinomas and triple-negative cases. In a retrospective Kaplan-Meier survival analysis, there was a statistical trend that high CML accumulation correlated with a more favorable prognosis (relapse-free survival, RFS) under tamoxifen treatment (p = 0.1). In estrogen receptor-negative cases, the high CML content was significantly correlated with an unfavorable outcome (RFS) of chemotherapy (p = 0.046). CML is a therefore a potentially predictive marker for the treatment of breast cancer patients with tamoxifen or chemotherapy.

  1. In skeletal muscle advanced glycation end products (AGEs) inhibit insulin action and induce the formation of multimolecular complexes including the receptor for AGEs.

    PubMed

    Cassese, Angela; Esposito, Iolanda; Fiory, Francesca; Barbagallo, Alessia P M; Paturzo, Flora; Mirra, Paola; Ulianich, Luca; Giacco, Ferdinando; Iadicicco, Claudia; Lombardi, Angela; Oriente, Francesco; Van Obberghen, Emmanuel; Beguinot, Francesco; Formisano, Pietro; Miele, Claudia

    2008-12-26

    Chronic hyperglycemia promotes insulin resistance at least in part by increasing the formation of advanced glycation end products (AGEs). We have previously shown that in L6 myotubes human glycated albumin (HGA) induces insulin resistance by activating protein kinase Calpha (PKCalpha). Here we show that HGA-induced PKCalpha activation is mediated by Src. Coprecipitation experiments showed that Src interacts with both the receptor for AGE (RAGE) and PKCalpha in HGA-treated L6 cells. A direct interaction of PKCalpha with Src and insulin receptor substrate-1 (IRS-1) has also been detected. In addition, silencing of IRS-1 expression abolished HGA-induced RAGE-PKCalpha co-precipitation. AGEs were able to induce insulin resistance also in vivo, as insulin tolerance tests revealed a significant impairment of insulin sensitivity in C57/BL6 mice fed a high AGEs diet (HAD). In tibialis muscle of HAD-fed mice, insulin-induced glucose uptake and protein kinase B phosphorylation were reduced. This was paralleled by a 2.5-fold increase in PKCalpha activity. Similarly to in vitro observations, Src phosphorylation was increased in tibialis muscle of HAD-fed mice, and co-precipitation experiments showed that Src interacts with both RAGE and PKCalpha. These results indicate that AGEs impairment of insulin action in the muscle might be mediated by the formation of a multimolecular complex including RAGE/IRS-1/Src and PKCalpha.

  2. Measurement of advanced glycation endproducts in skin of patients with rheumatoid arthritis, osteoarthritis, and dialysis-related spondyloarthropathy using non-invasive methods.

    PubMed

    Matsumoto, Tomoko; Tsurumoto, Toshiyuki; Baba, Hideo; Osaki, Makoto; Enomoto, Hiroshi; Yonekura, Akihiko; Shindo, Hiroyuki; Miyata, Toshio

    2007-12-01

    Advanced glycation endproducts (AGEs) are the products of non-enzymatic glycation and oxidation of proteins and lipids. Low-turnover tissues such as articular cartilage seem to be susceptible to the accumulation of AGEs, which might lead to cartilage degradation. Recently, a non-invasive method for measuring skin AGE accumulation was developed by using the Autofluorescence Reader (AFR). To examine the usefulness of measuring skin AGE in patients with bone and joint diseases, we examined autofluorescence (AF) levels in skin of patients with osteoarthritis (OA), rheumatoid arthritis (RA), and dialysis-related spondyloarthropathy (DRSA). Ninety-three patients with RA, 24 patients with OA, and 29 patients with DRSA were examined, and 43 healthy volunteers were used as controls. Skin AF was assessed on the lower arm with the AGE-Reader. Mean AF was significantly higher in the patients with RA (median 2.13 and range 1.25-2.94) or with DRSA (median 2.21 and range 1.29-3.88) than in the patients with OA (median 1.63 and range 1.07-2.31) or in the controls (median 1.74 and range 1.10-2.46). There was no significant difference between OA and the controls, or between RA and DRSA. These findings suggest that differences of AGE accumulation in the skin might reflect the different pathologies of these diseases.

  3. Female reproductive dysfunction during ageing: role of methylglyoxal in the formation of advanced glycation endproducts in ovaries of reproductively-aged mice.

    PubMed

    Tatone, C; Carbone, M C; Campanella, G; Festuccia, C; Artini, P G; Talesa, V; Focarelli, R; Amicarelli, F

    2010-01-01

    Reproductive dysfunction with ageing has been so far extensively characterized in terms of depletion of ovarian follicles and reduced ability to produce gametes competent for fertilization. Nevertheless, molecular mechanisms underlying this process are still poorly understood. In the present study we addressed the hypothesis that methylglyoxal (MG), a major precursor of Advanced Glycation Endproducts (AGE), may contribute to molecular damage occurring during ovarian ageing. Our results showed that the biochemical activity of glyoxalase 1, the main component of the MG scavenging system, is significantly decreased in ovaries from reproductively-aged mice in comparison with the young group. This effect was associated with decreased expression at protein and RNA level of this enzyme and increased intraovarian level of MG. MG-arginine adducts argpyrimidine as detected with a specific antibody was found to accumulate with ageing in specific ovarian compartments. Separation of ovarian proteins by 2D gels and Western blotting revealed an approximate 30-fold increase in the extent of protein glycation in aged ovaries along with the appearance of eight argpyrimidine modified proteins exclusive for the aged group. In conclusion, the present results show that impaired MG detoxification causing relevant damage to the ovarian proteome might be one of the mechanisms underlying reproductive ageing and/or ageing-like ovarian diseases.

  4. Inhibition of Advanced Glycation End-Product Formation and Antioxidant Activity by Extracts and Polyphenols from Scutellaria alpina L. and S. altissima L.

    PubMed

    Grzegorczyk-Karolak, Izabela; Gołąb, Krzysztof; Gburek, Jakub; Wysokińska, Halina; Matkowski, Adam

    2016-06-14

    Methanolic extracts from the aerial parts and roots of two Scutellaria species, S. alpina and S. altissima, and five polyphenols from these plants demonstrated a significant ability to inhibit the formation of advanced glycation end-products (AGE) in vitro. S. alpina, which is richer in polyphenolic compounds, had strong antiglycation properties. These extracts demonstrated also high activity in the FRAP (ferric-reducing antioxidant power), antiradical (DPPH) and lipid peroxidation inhibition assays. Among the pure compounds, baicalin was the strongest glycation inhibitor (90.4% inhibition at 100 μg/mL), followed by luteolin (85.4%). Two other flavone glycosides had about half of this activity. Verbascoside was similar to the reference drug aminoguanidine (71.2% and 75.9%, respectively). The strong correlation observed between AGE inhibition and total flavonoid content indicated that flavonoids contribute significantly to antiglycation properties. A positive correlation was also observed between antiglycative and antioxidant activities. The studied skullcap species can be considered as a potential source of therapeutic agents for hyperglycemia-related disorders.

  5. Glycation Reactions of Casein Micelles.

    PubMed

    Moeckel, Ulrike; Duerasch, Anja; Weiz, Alexander; Ruck, Michael; Henle, Thomas

    2016-04-13

    After suspensions of micellar casein or nonmicellar sodium caseinate had been heated, respectively, in the presence and absence of glucose for 0-4 h at 100 °C, glycation compounds were quantitated. The formation of Amadori products as indicators for the "early" Maillard reaction were in the same range for both micellar and nonmicellar caseins, indicating that reactive amino acid side chains within the micelles are accessible for glucose in a comparable way as in nonmicellar casein. Significant differences, however, were observed concerning the formation of the advanced glycation end products (AGEs), namely, N(ε)-carboxymethyllysine (CML), pyrraline, pentosidine, and glyoxal-lysine dimer (GOLD). CML could be observerd in higher amounts in nonmicellar casein, whereas in the micelles the pyrraline formation was increased. Pentosidine and GOLD were formed in comparable amounts. Furthermore, the extent of protein cross-linking was significantly higher in the glycated casein micelles than in the nonmicellar casein samples. Dynamic light scattering and scanning electron microscopy showed that glycation has no influence on the size of the casein micelles, indicating that cross-linking occurs only in the interior of the micelles, but altered the surface morphology. Studies on glycation and nonenzymatic cross-linking can contribute to the understanding of the structure of casein micelles.

  6. Chicken albumin exhibits natural resistance to glycation.

    PubMed

    Zuck, Jessica; Borges, Chad R; Braun, Eldon J; Sweazea, Karen L

    2017-01-01

    Glycation of proteins and subsequent production of advanced glycation end products (AGEs) is a major contributor to the pathophysiology of diabetes. The objective of the present study was to compare the glycation of avian and human serum albumin to elucidate the mechanisms by which protein glycation in birds is prevented in the presence of naturally high plasma glucose concentrations. Solutions of purified chicken and human serum albumin (CSA and HSA) were prepared with four different glucose concentrations (0, 5.56, 11.1, and 22.2mM) and incubated at three temperatures (37.0, 39.8, and 41.4°C) for seven days. The solutions were sampled on Days 0, 3, and 7 and analyzed by liquid chromatography-electrospray ionization-mass spectrometry for the presence of glycated albumin. Four-way repeated measures ANOVA (p=0.032) indicate that all independent variables (albumin type, glucose concentration, temperature and time) interacted to affect the degree of glycation. With increasing glucose concentration, the glycation of both HSA and CSA increased with time at all temperatures. In addition, HSA was glycated to a greater extent than CSA at the two higher glucose concentrations for all temperature conditions. Glycation was elevated with increasing temperatures for HSA but not CSA. The results suggest an inherent difference between human and chicken albumin that contributes to the observed differences in glycation. Further research is needed to characterize this inherent difference in an effort to elucidate mechanisms by which avian plasma protein is glycated to a lesser degree than that of mammals (humans).

  7. Glycation of antibodies: Modification, methods and potential effects on biological functions.

    PubMed

    Wei, Bingchuan; Berning, Kelsey; Quan, Cynthia; Zhang, Yonghua Taylor

    2017-03-08

    Glycation is an important protein modification that could potentially affect bioactivity and molecular stability, and glycation of therapeutic proteins such as monoclonal antibodies should be well characterized. Glycated protein could undergo further degradation into advance glycation end (AGE) products. Here, we review the root cause of glycation during the manufacturing, storage and in vivo circulation of therapeutic antibodies, and the current analytical methods used to detect and characterize glycation and AGEs, including boronate affinity chromatography, charge-based methods, liquid chromatography-mass spectrometry and colorimetric assay. The biological effects of therapeutic protein glycation and AGEs, which ranged from no affect to loss of activity, are also discussed.

  8. A Snapshot of the Plant Glycated Proteome

    PubMed Central

    Bilova, Tatiana; Lukasheva, Elena; Brauch, Dominic; Greifenhagen, Uta; Paudel, Gagan; Tarakhovskaya, Elena; Frolova, Nadezhda; Mittasch, Juliane; Balcke, Gerd Ulrich; Tissier, Alain; Osmolovskaya, Natalia; Vogt, Thomas; Wessjohann, Ludger A.; Birkemeyer, Claudia; Milkowski, Carsten; Frolov, Andrej

    2016-01-01

    Glycation is the reaction of carbonyl compounds (reducing sugars and α-dicarbonyls) with amino acids, lipids, and proteins, yielding early and advanced glycation end products (AGEs). The AGEs can be formed via degradation of early glycation intermediates (glycoxidation) and by interaction with the products of monosaccharide autoxidation (autoxidative glycosylation). Although formation of these potentially deleterious compounds is well characterized in animal systems and thermally treated foods, only a little information about advanced glycation in plants is available. Thus, the knowledge of the plant AGE patterns and the underlying pathways of their formation are completely missing. To fill this gap, we describe the AGE-modified proteome of Brassica napus and characterize individual sites of advanced glycation by the methods of liquid chromatography-based bottom-up proteomics. The modification patterns were complex but reproducible: 789 AGE-modified peptides in 772 proteins were detected in two independent experiments. In contrast, only 168 polypeptides contained early glycated lysines, which did not resemble the sites of advanced glycation. Similar observations were made with Arabidopsis thaliana. The absence of the early glycated precursors of the AGE-modified protein residues indicated autoxidative glycosylation, but not glycoxidation, as the major pathway of AGE formation. To prove this assumption and to identify the potential modifying agents, we estimated the reactivity and glycative potential of plant-derived sugars using a model peptide approach and liquid chromatography-mass spectrometry-based techniques. Evaluation of these data sets together with the assessed tissue carbohydrate contents revealed dihydroxyacetone phosphate, glyceraldehyde 3-phosphate, ribulose, erythrose, and sucrose as potential precursors of plant AGEs. PMID:26786108

  9. Induction of synthesis and secretion of interleukin 1 beta in the human monocytic THP-1 cells by human serum albumins modified with methylglyoxal and advanced glycation endproducts.

    PubMed

    Westwood, M E; Thornalley, P J

    1996-04-01

    Human serum albumin modified with 1-2 methylglyoxal residues per molecule of protein (MGmin-HSA) stimulated the synthesis and secretion of interleukin 1 beta (IL-1 beta) from human monocytic THP-1 cells in vitro. It was a more potent inducer of IL-1 beta synthesis than human serum albumin highly-modified with glucose-derived advanced glycation endproducts (AGE-HSA). With 20 microM ligand. IL-1 beta synthesis was (pg/10(6) cells): MGmin-HSA 484.5 +/- 50.3; AGE-HSA 30.6 +/- 2.0 (n = 3). IL-1 beta synthesis increased markedly with MGmin-HSA concentrations > 5 microM. IL-1 beta synthesis and secretion from monocytes in response to methylglyoxal-modified proteins in vivo may contribute to the development of macro- and micro-angiopathy, particularly in diabetes mellitus.

  10. Quantitative analysis of methylglyoxal, glyoxal and free advanced glycation end-products in the plasma of Wistar rats during the oral glucose tolerance test.

    PubMed

    Chen, Si Jing; Aikawa, Chiwa; Matsui, Toshiro

    2015-01-01

    The purpose of this study was to gain insight into the production behavior of free adducts of advanced glycation end-products (AGEs) in Wistar rats under acute hyperglycemic conditions. Five AGE-free adducts as well as their precursors (i.e., highly reactive carbonyl intermediates of methylglyoxal and glyoxal) in rat plasma were quantitatively determined at greater than nanomolar levels using the liquid chromatography/tandem mass spectrometry method coupled with 2,4,6-trinitrobenzene sulfonate and 2,3-diaminonaphthalene derivatization techniques. An oral glucose (2 g/kg dose) tolerance test to 10-week-old Wistar rats provided evidence that the plasma levels of diabetes-related metabolites did not change acutely within 120 min, irrespective of increasing blood glucose levels.

  11. Beneficial effects of cinnamon proanthocyanidins on the formation of specific advanced glycation endproducts and methylglyoxal-induced impairment on glucose consumption.

    PubMed

    Peng, Xiaofang; Ma, Jinyu; Chao, Jianfei; Sun, Zheng; Chang, Raymond Chuen-Chung; Tse, Iris; Li, Edmund T S; Chen, Feng; Wang, Mingfu

    2010-06-09

    Advanced glycation endproducts (AGEs) are a group of complex and heterogeneous compounds formed from nonenzymatic reactions. The accumulation of AGEs in vivo has been implicated as a major pathogenic process in diabetic complications and other health disorders, such as atherosclerosis and Alzheimer's disease, and normal aging. In this study, we investigate the inhibitory effects of cinnamon bark proanthocyanidins, catechin, epicatechin, and procyanidin B2 on the formation of specific AGE representatives including pentosidine, N(epsilon)-(carboxymethyl)lysine (CML), and methylglyoxal (MGO) derived AGEs. These compounds displayed obvious inhibitory effects on these specific AGEs, which are largely attributed to both their antioxidant activities and carbonyl scavenging capacities. Meanwhile, in terms of their potent MGO scavenging capacities, effects of these proanthocyanidins on insulin signaling pathways interfered by MGO were evaluated in 3T3-L1 adipocytes. According to the results, proanthocyanidins exerted protective effects on glucose consumption impaired by MGO in 3T3-L1 fat cells.

  12. Clinical application prospect of umbilical cord-derived mesenchymal stem cells on clearance of advanced glycation end products through autophagy on diabetic wound.

    PubMed

    Han, Yanfu; Sun, Tianjun; Tao, Ran; Han, Yanqing; Liu, Jing

    2017-03-24

    Nowadays, wound healing delay due to diabetes is considered to be closely related to the accumulation of advanced glycation end products (AGEs). Although mesenchymal stem cells (MSCs) exhibit positive effects on diabetic wound healing, related mechanisms are still not fully elucidated. It has been reported that MSCs can improve the activity of autophagy in injured tissues, thereby playing an important role in wound healing. The autophagy induced by MSCs may be beneficial to diabetic wound healing via removing AGEs, which provide new ideas for clinical treatment of diabetic wounds with the potential of broad application prospects. In this study, the current research situation and application prospect of umbilical cord-derived MSCs on the clearance of AGEs in diabetic wound were reviewed.

  13. Toll-like Receptors, Triggering Receptor Expressed on Myeloid Cells Family Members and Receptor for Advanced Glycation End-products in Allergic Airway Inflammation

    PubMed Central

    Hall, Sannette C.; Agrawal, Devendra K.

    2016-01-01

    Asthma is a chronic disorder of the airways characterized by cellular infiltration, airway hyper-responsive and airway inflammation. Innate immune cells are the first line of defense against endogenous and exogenous signals in the airways and as such possess a diverse array of pattern recognition receptors. Toll-like receptors are crucial sentinels which when activated, can either promote or ameliorate the inflammatory response in predisposed individuals. The recently discovered triggering receptor expressed on myeloid cells family members are emerging mediators of inflammation. These receptors are believed to modulate inflammatory responses by collaborating with classic PRRs. Endogenous signals like HMGB-1, signaling through the receptor for advanced glycation end products, also promotes inflammation, however, its contribution to inflammation in the airways is not well known. Here, we discuss the role of each receptor in airway inflammation and highlight potential synergistic mechanisms, which contribute to disease pathogenesis in allergic asthma. PMID:26678062

  14. Possible participation of receptor for advanced glycation end products (RAGE) in the origin of cancer stem cells in diabetic patients with colon cancer.

    PubMed

    Hu, Xiang; Cheng, Yong

    2013-05-01

    The association between diabetes and the associated increased risk of several solid malignancies has been the subject of investigation for many years, while potential biologic links between the two diseases are incompletely understood. The receptor for advanced glycation end-products (RAGE) signal transduction may represent a focal point in their respective contributions to malignant transformation associated diabetes. While the physiopathology of RAGE axis in promoting malignancies cannot be explained completely by the available mechanism as perpetuating inflammation at tumor microenvironment. In addition, experimental researches revealed a crucial role for upstreams of RAGE signaling pathway in maintaining the stemness properties and tumorigenicity of cancer stem cells. Hence, we hypothesized that RAGE inducing cancer stem cells may be a key determinant in the origin and progression of colon malignant tumors concomitant diabetes. Such an opinion not only bands together the seemingly disparate various complications in diabetes and colon cancers, but also has future implications for risk assessment and biopharmaceutical treatment.

  15. Vitamin A (retinol) up-regulates the receptor for advanced glycation endproducts (RAGE) through p38 and Akt oxidant-dependent activation.

    PubMed

    Gelain, Daniel Pens; de Bittencourt Pasquali, Matheus Augusto; Caregnato, Fernanda Freitas; Moreira, José Claudio Fonseca

    2011-10-28

    Retinol (vitamin A) is believed to exert preventive/protective effects against malignant, neurodegenerative and cardiovascular diseases by acting as an antioxidant. However, later clinical and experimental data show a pro-oxidant action of retinol and other retinoids at specific conditions. The receptor for advanced glycation endproducts (RAGE) is a pattern recognition receptor, being activated by different ligands such as S100 proteins, HMGB1 (amphoterin), β-amyloid peptide and advanced glycation endproducts (AGE). RAGE activation influences a wide range of pathological conditions such as diabetes, pro-inflammatory states and neurodegenerative processes. Here, we investigated the involvement of different mitogen-activated protein kinases (MAPK: ERK1/2, p38 and JNK), PKC, PKA and Akt in the up-regulation of RAGE by retinol. As previously reported, we observed that the increase in RAGE immunocontent by retinol is reversed by antioxidant co-treatment, indicating the involvement of oxidative stress in this process. Furthermore, the p38 inhibitor SB203580 and the Akt inhibitor LY294002 also decreased the effect of retinol on RAGE levels, suggesting the involvement of these protein kinases in such effect. Both p38 and Akt phosphorylation were increased by treatment with pro-oxidant concentrations of retinol, and the antioxidant co-treatment blocked this effect, indicating that activation of p38 and Akt during retinol treatment is dependent on reactive species production. The 2',7'-dichlorohydrofluorescein diacetate (DCFH) assay also indicated that retinol treatment enhances cellular reactive species production. Altogether, these data indicate that RAGE up-regulation by retinol is mediated by the free radical-dependent activation of p38 and Akt.

  16. Hypoxia-induced increases in glucose uptake do not cause oxidative injury or advanced glycation end-product (AGE) formation in vascular endothelial cells

    PubMed Central

    Viator, Ryan J; Khader, Heba; Hingorani, Neha; Long, Sara; Solodushko, Victor; Fouty, Brian

    2015-01-01

    An increase in glucose uptake by endothelial cells exposed to hyperglycemia is the presumed initiating event that causes systemic vascular disease in individuals with diabetes. Diabetics do not develop clinically significant pulmonary vascular disease, however, despite the pulmonary circulation’s exposure to the same level of glucose. We hypothesized that pulmonary artery endothelial cells are protected from the detrimental effects of hyperglycemia because they take up less glucose than endothelial cells in the systemic circulation, either because of intrinsic differences between the two cell types or because the lower oxygen tension in the pulmonary arterial blood depresses glucose uptake. To test this hypothesis, we exposed normoglycemic and hyperglycemic bovine pulmonary artery (PAECs) and aortic endothelial cells (AECs) from the same animal to progressively lower oxygen tensions and determined glucose uptake. In contrast with our initial hypothesis, we detected no significant difference in glucose uptake between the two cell types. Furthermore, glucose uptake in both PAECs and AECs increased, not decreased, as the oxygen tension dropped; this oxygen-dependent increase in glucose uptake in endothelial cells predominated over the hyperglycemia-mediated decrease in glucose uptake that has been reported by others. Despite the increase in glucose uptake at lower oxygen tensions, we detected no corresponding increase in protein carbonylation or advanced glycation endproducts. These results demonstrate that small physiologically relevant changes in oxygen tension can have an important impact on glucose uptake in endothelial cells. These results also demonstrate that an increase in glucose uptake, by itself, is not sufficient to generate ROS-mediated protein carbonylation or increase intracellular advanced glycation endproducts in vascular endothelial cells. PMID:26177960

  17. Inhibition of Advanced Glycation End Products (AGEs) Accumulation by Pyridoxamine Modulates Glomerular and Mesangial Cell Estrogen Receptor α Expression in Aged Female Mice.

    PubMed

    Pereira-Simon, Simone; Rubio, Gustavo A; Xia, Xiaomei; Cai, Weijing; Choi, Rhea; Striker, Gary E; Elliot, Sharon J

    2016-01-01

    Age-related increases in oxidant stress (OS) play a role in regulation of estrogen receptor (ER) expression in the kidneys. In this study, we establish that in vivo 17β-estradiol (E2) replacement can no longer upregulate glomerular ER expression by 21 months of age in female mice (anestrous). We hypothesized that advanced glycation end product (AGE) accumulation, an important source of oxidant stress, contributes to these glomerular ER expression alterations. We treated 19-month old ovariectomized female mice with pyridoxamine (Pyr), a potent AGE inhibitor, in the presence or absence of E2 replacement. Glomerular ERα mRNA expression was upregulated in mice treated with both Pyr and E2 replacement and TGFβ mRNA expression decreased compared to controls. Histological sections of kidneys demonstrated decreased type IV collagen deposition in mice receiving Pyr and E2 compared to placebo control mice. In addition, anti-AGE defenses Sirtuin1 (SIRT1) and advanced glycation receptor 1 (AGER1) were also upregulated in glomeruli following treatment with Pyr and E2. Mesangial cells isolated from all groups of mice demonstrated similar ERα, SIRT1, and AGER1 expression changes to those of whole glomeruli. To demonstrate that AGE accumulation contributes to the observed age-related changes in the glomeruli of aged female mice, we treated mesangial cells from young female mice with AGE-BSA and found similar downregulation of ERα, SIRT1, and AGER1 expression. These results suggest that inhibition of intracellular AGE accumulation with pyridoxamine may protect glomeruli against age-related oxidant stress by preventing an increase of TGFβ production and by regulation of the estrogen receptor.

  18. Increased Expression of Tissue Factor and Receptor for Advanced Glycation End Products in Peripheral Blood Mononuclear Cells of Patients With Type 2 Diabetes Mellitus with Vascular Complications

    PubMed Central

    Buchs, A. E.; Kornberg, A.; Zahavi, M.; Aharoni, D.; Zarfati, C.; Rapoport, M. J.

    2004-01-01

    The aim of the study was to determine the correlation between the expression of tissue factor (TF) and the receptor for advanced glycation end products (RAGEs) and vascular complications in patients with longstanding uncontrolled type 2 diabetes (T2D). TF and RAGE mRNAs as well as TF antigen and activity were investigated in 21 T2D patients with and without vascular complications. mRNA expression was assessed by reverse transcriptase–polymerase chain reaction (RT-PCR) in nonstimulated and advanced glycation end product (AGE) albumin–stimulated peripheral blood mononuclear cells (PBMCs). TF antigen expression was determined by enzyme-linked immunosorbent assay (ELISA) and TF activity by a modified prothrombin time assay. Basal RAGE mRNA expression was 0.2 ± 0.06 in patients with complications and 0.05 ± 0.06 patients without complications (P = .004). Stimulation did not cause any further increase in either group. TF mRNA was 0.58 ± 0.29 in patients with complications and 0.21 ± 0.18 in patients without complications (P = .003). Stimulation resulted in a nonsignificant increase in both groups. Basal TF activity (U/106 PBMCs) was 18.4 ± 13.2 in patients with complications and 6.96 ± 5.2 in patients without complications (P = .003). It increased 3-fold in both groups after stimulation (P = .001). TF antigen (pg/106 PBMCs) was 33.7 ± 28.6 in patients with complications, 10.4 ± 7.8 in patients without complications (P = .02). Stimulation tripled TF antigen in both groups of patients (P = .001). The RAGE/TF axis is up-regulated inT2Dpatients with vascular complications as compared to patients without complications. This suggests a role for this axis in the pathogenesis of vascular complications in T2D. PMID:15203887

  19. Deleterious effects of reactive aldehydes and glycated proteins on macrophage proteasomal function: possible links between diabetes and atherosclerosis.

    PubMed

    Moheimani, Fatemeh; Morgan, Philip E; van Reyk, David M; Davies, Michael J

    2010-06-01

    People with diabetes experience chronic hyperglycemia and are at a high risk of developing atherosclerosis and microvascular disease. Reactions of glucose, or aldehydes derived from glucose (e.g. methylglyoxal, glyoxal, or glycolaldehyde), with proteins result in glycation that ultimately yield advanced glycation end products (AGE). AGE are present at elevated levels in plasma and atherosclerotic lesions from people with diabetes, and previous in vitro studies have postulated that the presence of these materials is deleterious to cell function. This accumulation of AGE and glycated proteins within cells may arise from either increased formation and/or ineffective removal by cellular proteolytic systems, such as the proteasomes, the major multi-enzyme complex that removes proteins within cells. In this study it is shown that whilst high glucose concentrations fail to modify proteasome enzyme activities in J774A.1 macrophage-like cell extracts, reactive aldehydes enhanced proteasomal enzyme activities. In contrast BSA, pre-treated with high glucose for 8 weeks, inhibited both the chymotrypsin-like and caspase-like activities. BSA glycated using methylglyoxal or glycolaldehyde, also inhibited proteasomal activity though to differing extents. This suppression of proteasome activity by glycated proteins may result in further intracellular accumulation of glycated proteins with subsequent deleterious effects on cellular function.

  20. Synchrotron infrared imaging of advanced glycation endproducts (AGEs) in cardiac tissue from mice fed high glycemic diets

    PubMed Central

    Birarda, Giovanni; Holman, Elizabeth A.; Fu, Shang; Weikel, Karen; Hu, Ping; Blankenberg, Francis G.; Holman, Hoi-Ying; Taylor, Allen

    2015-01-01

    Recent research findings correlate an increased risk for dieases such as diabetes, macular degeneration and cardiovascular disease (CVD) with diets that rapidly raise the blood sugar levels; these diets are known as high glycemic index (GI) diets which include white breads, sodas and sweet deserts. Lower glycemia diets are usually rich in fruits, non-starchy vegetables and whole grain products. The goal of our study was to compare and contrast the effects of a low vs. high glycemic diet using the biochemical composition and microstructure of the heart. The improved spatial resolution and signal-to-noise for SR-FTIR obtained through the coupling of the bright synchrotron infrared photon source to an infrared spectral microscope enabled the molecular-level observation of diet-related changes within unfixed fresh frozen histologic sections of mouse cardiac tissue. High and low glycemic index (GI) diets were started at the age of five-months and continued for one year, with the diets only differing in their starch distribution (high GI diet = 100% amylopectin versus low GI diet = 30% amylopectin/70% amylose). Serial cryosections of cardiac tissue for SR-FTIR imaging alternated with adjacent hematoxylin and eosin (H&E) stained sections allowed not only fine-scale chemical analyses of glycogen and glycolipid accumulation along a vein as well as protein glycation hotspots co-localizing with collagen cold spots but also the tracking of morphological differences occurring in tandem with these chemical changes. As a result of the bright synchrotron infrared photon source coupling, we were able to provide significant molecular evidence for a positive correlation between protein glycation and collagen degradation in our mouse model. Our results bring a new insight not only to the effects of long-term GI dietary practices of the public but also to the molecular and chemical foundation behind the cardiovascular disease pathogenesis commonly seen in diabetic patients. PMID

  1. Synchrotron infrared imaging of advanced glycation endproducts (AGEs) in cardiac tissue from mice fed high glycemic diets.

    PubMed

    Birarda, Giovanni; Holman, Elizabeth A; Fu, Shang; Weikel, Karen; Hu, Ping; Blankenberg, Francis G; Holman, Hoi-Ying; Taylor, Allen

    Recent research findings correlate an increased risk for dieases such as diabetes, macular degeneration and cardiovascular disease (CVD) with diets that rapidly raise the blood sugar levels; these diets are known as high glycemic index (GI) diets which include white breads, sodas and sweet deserts. Lower glycemia diets are usually rich in fruits, non-starchy vegetables and whole grain products. The goal of our study was to compare and contrast the effects of a low vs. high glycemic diet using the biochemical composition and microstructure of the heart. The improved spatial resolution and signal-to-noise for SR-FTIR obtained through the coupling of the bright synchrotron infrared photon source to an infrared spectral microscope enabled the molecular-level observation of diet-related changes within unfixed fresh frozen histologic sections of mouse cardiac tissue. High and low glycemic index (GI) diets were started at the age of five-months and continued for one year, with the diets only differing in their starch distribution (high GI diet = 100% amylopectin versus low GI diet = 30% amylopectin/70% amylose). Serial cryosections of cardiac tissue for SR-FTIR imaging alternated with adjacent hematoxylin and eosin (H&E) stained sections allowed not only fine-scale chemical analyses of glycogen and glycolipid accumulation along a vein as well as protein glycation hotspots co-localizing with collagen cold spots but also the tracking of morphological differences occurring in tandem with these chemical changes. As a result of the bright synchrotron infrared photon source coupling, we were able to provide significant molecular evidence for a positive correlation between protein glycation and collagen degradation in our mouse model. Our results bring a new insight not only to the effects of long-term GI dietary practices of the public but also to the molecular and chemical foundation behind the cardiovascular disease pathogenesis commonly seen in diabetic patients.

  2. Glycation of human γB-crystallin: A biophysical investigation.

    PubMed

    Chaudhury, Susmitnarayan; Ghosh, Pooja; Parveen, Sultana; Dasgupta, Swagata

    2017-03-01

    Glycation of ocular lens proteins plays a vital role in the development of diabetic cataract. In order to investigate the role of glycation in cataractogenesis, the extent of glycation of human γB-crystallin was determined by an in vitro glycation study in a solution of high glucose content for upto 28days. The glycated protein has been purified and the formation of advanced glycation end products (AGEs) has been monitored spectroscopically. Size exclusion chromatographic studies showed that the covalent intermolecular crosslinking in the dimer formed was not due to disulfide bond formation. MALDI-TOF spectroscopy was employed to determine the number of glucose moieties attached to the protein due to glycation.

  3. Effects of high glucose and advanced glycation end products on the expressions of sclerostin and RANKL as well as apoptosis in osteocyte-like MLO-Y4-A2 cells

    SciTech Connect

    Tanaka, Ken-ichiro Yamaguchi, Toru Kanazawa, Ippei Sugimoto, Toshitsugu

    2015-05-29

    In diabetes mellitus (DM), high glucose (HG) and advanced glycation end products (AGEs) are involved in bone quality deterioration. Osteocytes produce sclerostin and receptor activator of nuclear factor-kB ligand (RANKL) and regulate osteoblast and osteoclast function. However, whether HG or AGEs directly affect osteocytes and regulate sclerostin and RANKL production is unknown. Here, we examined the effects of HG, AGE2, and AGE3 on the expression of sclerostin and RANKL and on apoptosis in osteocyte-like MLO-Y4-A2 cells. Treatment of the cells with 22 mM glucose, 100 μg/mL either AGE2 or AGE3 significantly increased the expression of sclerostin protein and mRNA; however, both AGEs, but not glucose, significantly decreased the expression of RANKL protein and mRNA. Moreover, treatment of the cells with HG, AGE2, or AGE3 for 72 h induced significant apoptosis. These detrimental effects of HG, AGE2, and AGE3 on sclerostin and RANKL expressions and on apoptosis were antagonized by pretreatment of the cells with 10{sup −8} M human parathyroid hormone (PTH)-(1–34). Thus, HG and AGEs likely suppress bone formation by increasing sclerostin expression in osteocytes, whereas AGEs suppress bone resorption by decreasing RANKL expression. Together, these processes may cause low bone turnover in DM. In addition, HG and AGEs may cause cortical bone deterioration by inducing osteocyte apoptosis. PTH may effectively treat these pathological processes and improve osteocyte function. - Highlights: • AGEs are involved in bone quality deterioration in diabetes mellitus (DM). • AGEs increased sclerostin as well as apoptosis, and decreased RANKL in osteocytes. • The effects of AGEs on osteocyte function were antagonized by human PTH-(1–34). • AGEs may cause low bone turnover and cortical porosity in DM. • PTH may be effective in bone quality deterioration by improving osteocyte function.

  4. Presence of dopa and amino acid hydroperoxides in proteins modified with advanced glycation end products (AGEs): amino acid oxidation products as a possible source of oxidative stress induced by AGE proteins.

    PubMed Central

    Fu, S; Fu, M X; Baynes, J W; Thorpe, S R; Dean, R T

    1998-01-01

    Glycation and subsequent Maillard or browning reactions of glycated proteins, leading to the formation of advanced glycation end products (AGEs), are involved in the chemical modification of proteins during normal aging and have been implicated in the pathogenesis of diabetic complications. Oxidative conditions accelerate the browning of proteins by glucose, and AGE proteins also induce oxidative stress responses in cells bearing AGE receptors. These observations have led to the hypothesis that glycation-induced pathology results from a cycle of oxidative stress, increased chemical modification of proteins via the Maillard reaction, and further AGE-dependent oxidative stress. Here we show that the preparation of AGE-collagen by incubation with glucose under oxidative conditions in vitro leads not only to glycation and formation of the glycoxidation product Nepsilon-(carboxymethyl)lysine (CML), but also to the formation of amino acid oxidation products on protein, including m-tyrosine, dityrosine, dopa, and valine and leucine hydroperoxides. The formation of both CML and amino acid oxidation products was prevented by anaerobic, anti-oxidative conditions. Amino acid oxidation products were also formed when glycated collagen, prepared under anti-oxidative conditions, was allowed to incubate under aerobic conditions that led to the formation of CML. These experiments demonstrate that amino acid oxidation products are formed in proteins during glycoxidation reactions and suggest that reactive oxygen species formed by redox cycling of dopa or by the metal-catalysed decomposition of amino acid hydroperoxides, rather than by redox activity or reactive oxygen production by AGEs on protein, might contribute to the induction of oxidative stress by AGE proteins. PMID:9461515

  5. Advanced glycation end products of DNA: quantification of N2-(1-Carboxyethyl)-2'-deoxyguanosine in biological samples by liquid chromatography electrospray ionization tandem mass spectrometry.

    PubMed

    Synold, Timothy; Xi, Bixin; Wuenschell, Gerald E; Tamae, Daniel; Figarola, James L; Rahbar, Samuel; Termini, John

    2008-11-01

    Methylglyoxal (MG) and related alpha-oxoaldehydes react with proteins, lipids, and DNA to give rise to covalent adducts known as advanced glycation end products (AGEs). Elevated levels of AGEs have been implicated in the pathological complications of diabetes, uremia, Alzheimer's disease, and possibly cancer. There is therefore widespread interest in developing sensitive methods for the in vivo measurement of AGEs as prognostic biomarkers and for treatment monitoring. The two diastereomeric MG-DNA adducts of N(2)-(1-carboxyethyl)-2'-deoxyguanosine (CEdG) are the primary glycation products formed in DNA; however, accurate assessment of their distribution in vivo has not been possible since there is no readily available quantitative method for CEdG determination in biological samples. To address these issues, we have developed a sensitive and quantitative liquid chromatography electrospray ionization tandem mass spectrometry assay using the stable isotope dilution method with an (15)N(5)-CEdG standard. Methods for CEdG determination in urine or tissue extracted DNA are described. Changes in urinary CEdG in diabetic rats in response to oral administration of the AGE inhibitor LR-90 are used to demonstrate the potential utility of the method for treatment monitoring. Both stereoisomeric CEdG adducts were detected in a human breast tumor and normal adjacent tissue at levels of 3-12 adducts/10(7) dG, suggesting that this lesion may be widely distributed in vivo. Strategies for dealing with artifactual adduct formation due to oxoaldehyde generation during DNA isolation and enzymatic workup procedures are described.

  6. Curcumin eliminates the effect of advanced glycation end-products (AGEs) on the divergent regulation of gene expression of receptors of AGEs by interrupting leptin signaling.

    PubMed

    Tang, Youcai; Chen, Anping

    2014-05-01

    Non-alcoholic steatohepatitis (NASH) is a major risk factor for hepatic fibrogenesis. NASH is often found in diabetic patients with hyperglycemia. Hyperglycemia induces non-enzymatic glycation of proteins, yielding advanced glycation end-products (AGEs). Effects of AGEs are mainly mediated by two categories of cytoplasmic membrane receptors. Receptor for AGEs (RAGE) is associated with increased oxidative stress and inflammation, whereas AGE receptor-1 (AGE-R1) is involved in detoxification and clearance of AGEs. Activation of hepatic stellate cells (HSC) is crucial to the development of hepatic fibrosis. We recently reported that AGEs stimulated HSC activation likely by inhibiting gene expression of AGE-R1 and inducing gene expression of RAGE in HSC, which were eliminated by the antioxidant curcumin. This study is to test our hypothesis that curcumin eliminates the effects of AGEs on the divergent regulation of the two receptors of AGEs in HSC by interrupting the AGE-caused activation of leptin signaling, leading to the inhibition of HSC activation. We observed herein that AGEs activated leptin signaling by inducing gene expression of leptin and its receptor in HSC. Like AGEs, leptin differentially regulated gene expression of RAGE and AGE-R1. Curcumin eliminated the effects of AGEs in HSC by interrupting leptin signaling and activating transcription factor NF-E2 p45-related factor 2 (Nrf2), leading to the elevation of cellular glutathione and the attenuation of oxidative stress. In conclusions, curcumin eliminated the effects of AGEs on the divergent regulation of gene expression of RAGE and AGE-R1 in HSC by interrupting the AGE-caused activation of leptin signaling, leading to the inhibition of HSC activation.

  7. Increased glyoxalase I levels inhibit accumulation of oxidative stress and an advanced glycation end product in mouse mesangial cells cultured in high glucose.

    PubMed

    Kim, Ki Mo; Kim, Young Sook; Jung, Dong Ho; Lee, Jun; Kim, Jin Sook

    2012-01-15

    Chronic high glucose levels lead to the formation of advanced glycation end-products (AGEs) as well as AGE precursors, such as methylglyoxal (MG) and glyoxal, via non-enzymatic glycation reactions in patients with diabetic mellitus. Glyoxalase 1 (GLO-1) detoxifies reactive dicarbonyls that form AGEs. To investigate the interaction between AGEs and GLO-1 in mesangial cells (MCs) under diabetic conditions, AGE levels and markers of oxidative stress were measured in GLO-1-overexpressing MCs (GLO-1-MCs) cultured in high glucose. Furthermore, we also examined levels of high glucose-induced apoptosis in GLO-1-MCs. In glomerular MCs, high glucose levels increased the formation of both MG and argpyrimidine (an MG-derived adduct) as well as GLO-1 expression. GLO-1-MCs had lower intracellular levels of MG accumulation, 8-hydroxy-deoxyguanosine (an oxidative DNA damage marker), 4-hydroxyl-2-nonenal (a lipid peroxidation product), and nitrosylated protein (a marker of oxidative-nitrosative stress) compared to control cells. Expression of mitochondrial oxidative phosphorylation complexes I, II, and III was also decreased in GLO-1-MCs. Furthermore, fewer GLO-1-MCs showed evidence of apoptosis as determined by terminal deoxynucleotidyl transferase-mediated dUTP nick labeling assay, and activation of both poly (ADP-ribose) polymerase 1 cleavage and caspase-3 was lower in GLO-1-MCs than in control cells cultured in high glucose. These results suggest that GLO-1 plays a role in high glucose-mediated signaling by reducing MG accumulation and oxidative stress in diabetes mellitus.

  8. A capture method based on the VC1 domain reveals new binding properties of the human receptor for advanced glycation end products (RAGE).

    PubMed

    Degani, Genny; Altomare, Alessandra A; Colzani, Mara; Martino, Caterina; Mazzolari, Angelica; Fritz, Guenter; Vistoli, Giulio; Popolo, Laura; Aldini, Giancarlo

    2017-04-01

    The Advanced Glycation and Lipoxidation End products (AGEs and ALEs) are a heterogeneous class of compounds derived from the non-enzymatic glycation or protein adduction by lipoxidation break-down products. The receptor for AGEs (RAGE) is involved in the progression of chronic diseases based on persistent inflammatory state and oxidative stress. RAGE is a pattern recognition receptor (PRR) and the inhibition of the interaction with its ligands or of the ligand accumulation have a potential therapeutic effect. The N-terminal domain of RAGE, the V domain, is the major site of AGEs binding and is stabilized by the adjacent C1 domain. In this study, we set up an affinity assay relying on the extremely specific biological interaction AGEs ligands have for the VC1 domain. A glycosylated form of VC1, produced in the yeast Pichia pastoris, was attached to magnetic beads and used as insoluble affinity matrix (VC1-resin). The VC1 interaction assay was employed to isolate specific VC1 binding partners from in vitro generated AGE-albumins and modifications were identified/localized by mass spectrometry analysis. Interestingly, this method also led to the isolation of ALEs produced by malondialdehyde treatment of albumins. Computational studies provided a rational-based interpretation of the contacts established by specific modified residues and amino acids of the V domain. The validation of VC1-resin in capturing AGE-albumins from complex biological mixtures such as plasma and milk, may lead to the identification of new RAGE ligands potentially involved in pro-inflammatory and pro-fibrotic responses, independently of their structures or physical properties, and without the use of any covalent derivatization process. In addition, the method can be applied to the identification of antagonists of RAGE-ligand interaction.

  9. Curcumin eliminates the effect of advanced glycation end-products (AGEs) on the divergent regulation of gene expression of receptors of AGEs by interrupting leptin signaling

    PubMed Central

    Tang, Youcai; Chen, Anping

    2014-01-01

    Nonalcoholic steatohepatitis (NASH) is a major risk factor for hepatic fibrogenesis. NASH is often found in diabetic patients with hyperglycemia. Hyperglycemia induces non-enzymatic glycation of proteins, yielding advanced glycation end-products (AGEs). Effects of AGEs are mainly mediated by two categories of cytoplasmic membrane receptors. Receptor for AGEs (RAGE) is associated with increased oxidative stress and inflammation, whereas AGE receptor-1 (AGE-R1) is involved in detoxification and clearance of AGEs. Activation of hepatic stellate cells (HSC) is crucial to the development of hepatic fibrosis. We recently reported that AGEs stimulated HSC activation likely by inhibiting gene expression of AGE-R1 and inducing gene expression of RAGE in HSC, which were eliminated by the antioxidant curcumin. This study is to test our hypothesis that curcumin eliminates the effects of AGEs on the divergent regulation of the two receptors of AGEs in HSC by interrupting the AGEs-caused activation of leptin signaling, leading to the inhibition of HSC activation. We observed herein that AGEs activated leptin signaling by inducing gene expression of leptin and its receptor in HSC. Like AGEs, leptin differentially regulated gene expression of RAGE and AGE-R1. Curcumin eliminated the effects of AGEs in HSC by interrupting leptin signaling and activating transcription factor Nrf2, leading to the elevation of cellular glutathione and the attenuation of oxidative stress. In conclusions, curcumin eliminated the effects of AGEs on the divergent regulation of gene expression of RAGE and AGE-R1 in HSC by interrupting the AGEs-caused activation of leptin signaling, leading to the inhibition of HSC activation. PMID:24614199

  10. Effects of a new advanced glycation inhibitor, LR-90, on mitigating arterial stiffening and improving arterial elasticity and compliance in a diabetic rat model: aortic impedance analysis

    PubMed Central

    Satheesan, S; Figarola, J L; Dabbs, T; Rahbar, S; Ermel, R

    2014-01-01

    BACKGROUND AND PURPOSE We determined the effects of treatment with LR-90, an inhibitor of advanced glycation end products, on the mechanical properties of the arterial system in streptozotocin (STZ)-induced diabetic Sprague Dawley rats, using aortic impedance analysis, and further investigated the effects of LR-90 on the progression of aortic pathology. EXPERIMENTAL APPROACH STZ-induced diabetic rats were treated with or without LR-90 (50 mg L-1 in drinking water) for 8 weeks and compared with control groups. Arterial BP measurements, various metabolic parameters, aortic histopathology, collagen cross-linking, AGE accumulation, and RAGE protein expression in aortic tissue were determined. Pulsatile parameters were evaluated using a standard Fourier series expansion technique and impulse response function of the filtered aortic input impedance spectra. KEY RESULTS LR-90 reduced glycated haemoglobin and triglycerides levels, although it had no effect on the glycaemic status. LR-90 did not affect arterial BP, but prevented the diabetes-induced increase in peripheral resistance and variations in aortic distensibility, as it reduced aortic characteristic impedance by 21%. LR-90 also prevented the elevation in wave reflection factor, as indicated by a 22.5% reduction and an associated increase of 23.5% in wave transit time, suggesting it prevents the augmentation of the systolic load of the left ventricle. Moreover, LR-90 inhibited collagen cross-linking and the accumulation of AGE and RAGE in the vasculature of diabetic rats. CONCLUSIONS AND IMPLICATIONS Treatment with LR-90 may impart significant protection against diabetes-induced aortic stiffening and cardiac hypertrophy and provides an additional therapeutic option for treatment of AGE associated diabetic complications. PMID:24611770

  11. Advanced glycation end products of beta2-microglobulin in uremic patients as determined by high resolution mass spectrometry.

    PubMed

    Bertoletti, Laura; Regazzoni, Luca; Altomare, Alessandra; Colombo, Raffaella; Colzani, Mara; Vistoli, Giulio; Marchese, Loredana; Carini, Marina; De Lorenzi, Ersilia; Aldini, Giancarlo

    2014-03-01

    By using a high resolution top-down and bottom-up approach we identified and characterized the AGEs of beta2-microglobulin (β2-m) formed by incubating the protein in the presence of glucose and of the main reactive carbonyl species. Glucose induced glycation on the N-terminal residue, while glyoxal (GO) and methylglyoxal (MGO) covalently reacted with Arg3. Carboxymethyl (CM-R) and imidazolinone (R-GO) derivatives were identified in the case of GO and carboxyethyl arginine (CE-R) and methyl-imidazolinone (R-MGO) for MGO. Interestingly, α,β-unsaturated aldehydes [4-hydroxy-2-nonenal (HNE); 4-oxo-2-nonenal (ONE); acrolein (ACR)] did not induce any covalent modifications up to 100μM. The different reactivity of β2-m towards the different RCS was then rationalized by molecular modeling studies. The MS method was then applied to fully characterize the AGEs of β2-m isolated from the urine of uremic subjects. CM-R, CE-R and R-MGO were easily identified on Arg3 and their relative abundance in respect to the native protein determined by a semi-quantitative approach. Overall, the AGEs content of urinary β2-m ranged from 0.2 to 1% in uremic subjects. The results here reported offer novel insights and technical achievements for a potential biological role of AGEs-β2-m in pathological conditions.

  12. Soluble receptor for advanced glycation end-product (sRAGE)/pentosidine ratio: a potential risk factor determinant for type 2 diabetic retinopathy.

    PubMed

    Ng, Zhi Xiang; Chua, Kek Heng; Iqbal, Tajunisah; Kuppusamy, Umah Rani

    2013-04-03

    This study aims to investigate potential diabetic retinopathy (DR) risk factors by evaluating the circulating levels of pentosidine, soluble receptor for advanced glycation end-product (sRAGE), advanced oxidation protein product (AOPP) as well as glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities in DR patients. A total of 235 healthy controls, 171 type 2 diabetic without retinopathy (DNR) and 200 diabetic retinopathy (DR) patients were recruited. Plasma was extracted for the estimation of pentosidine, sRAGE, AOPP levels and GPx activity whereas peripheral blood mononuclear cells were disrupted for SOD activity measurement. DNR and DR patients showed significantly higher levels of plasma pentosidine, sRAGE and AOPP but lower GPx and SOD activities when compared to healthy controls. The sRAGE/pentosidine ratio in DR patients was significantly lower than the ratio detected in DNR patients. Proliferative DR patients had significantly higher levels of plasma pentosidine, sRAGE, AOPP and sRAGE/pentosidine ratio than non-proliferative DR patients. High HbA1c level, long duration of diabetes and low sRAGE/pentosidine ratio were determined as the risk factors for DR. This study suggests that sRAGE/pentosidine ratio could serve as a risk factor determinant for type 2 DR as it has a positive correlation with the severity of DR.

  13. Receptor for advanced glycation end-products regulates lung fluid balance via protein kinase C-gp91(phox) signaling to epithelial sodium channels.

    PubMed

    Downs, Charles A; Kreiner, Lisa H; Johnson, Nicholle M; Brown, Lou Ann; Helms, My N

    2015-01-01

    The receptor for advanced glycation end-products (RAGE), a multiligand member of the Ig family, may play a crucial role in the regulation of lung fluid balance. We quantified soluble RAGE (sRAGE), a decoy isoform, and advanced glycation end-products (AGEs) from the bronchoalveolar lavage fluid of smokers and nonsmokers, and tested the hypothesis that AGEs regulate lung fluid balance through protein kinase C (PKC)-gp91(phox) signaling to the epithelial sodium channel (ENaC). Human bronchoalveolar lavage samples from smokers showed increased AGEs (9.02 ± 3.03 μg versus 2.48 ± 0.53 μg), lower sRAGE (1,205 ± 292 pg/ml versus 1,910 ± 263 pg/ml), and lower volume(s) of epithelial lining fluid (97 ± 14 ml versus 133 ± 17 ml). sRAGE levels did not predict ELF volumes in nonsmokers; however, in smokers, higher volumes of ELF were predicted with higher levels of sRAGE. Single-channel patch clamp analysis of rat alveolar epithelial type 1 cells showed that AGEs increased ENaC activity measured as the product of the number of channels (N) and the open probability (Po) (NPo) from 0.19 ± 0.08 to 0.83 ± 0.22 (P = 0.017) and the subsequent addition of 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-N-oxyl decreased ENaC NPo to 0.15 ± 0.07 (P = 0.01). In type 2 cells, human AGEs increased ENaC NPo from 0.12 ± 0.05 to 0.53 ± 0.16 (P = 0.025) and the addition of 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-N-oxyl decreased ENaC NPo to 0.10 ± 0.03 (P = 0.013). Using molecular and biochemical techniques, we observed that inhibition of RAGE and PKC activity attenuated AGE-induced activation of ENaC. AGEs induced phosphorylation of p47(phox) and increased gp91(phox)-dependent reactive oxygen species production, a response that was abrogated with RAGE or PKC inhibition. Finally, tracheal instillation of AGEs promoted clearance of lung fluid, whereas concomitant inhibition of RAGE, PKC, and gp91(phox) abrogated the response.

  14. Deletion of receptor for advanced glycation end products exacerbates lymphoproliferative syndrome and lupus nephritis in B6-MRL Fas lpr/j mice.

    PubMed

    Goury, Antoine; Meghraoui-Kheddar, Aïda; Belmokhtar, Karim; Vuiblet, Vincent; Ortillon, Jeremy; Jaisson, Stéphane; Devy, Jerôme; Le Naour, Richard; Tabary, Thierry; Cohen, Jacques H M; Schmidt, Ann-Marie; Rieu, Philippe; Touré, Fatouma

    2015-04-15

    The receptor for advanced glycation end products (RAGE) is a pattern recognition receptor that interacts with advanced glycation end products, but also with C3a, CpG DNA oligonucleotides, and alarmin molecules such as HMGB1 to initiate a proinflammatory reaction. Systemic lupus erythematosus is an autoimmune disorder associated with the accumulation of RAGE ligands. We generated mice invalidated for RAGE in the lupus-prone B6-MRL Fas lpr/j background to determine the role of RAGE in the pathogenesis of systemic lupus erythematosus. We compared the phenotype of these mice with that of their wild-type and B6-MRL Fas lpr/j littermates. Lymphoproliferative syndrome, production of anti-dsDNA Abs, lupus nephritis, and accumulation of CD3(+)B220(+)CD4(-)CD8(-) autoreactive T cells (in the peripheral blood and the spleen) were significantly increased in B6-MRL Fas lpr/j RAGE(-/-) mice compared with B6-MRL Fas lpr/j mice (respectively p < 0.005, p < 0.05, p < 0.001, and p < 0.001). A large proportion of autoreactive T cells from B6-MRL Fas lpr/j mice expressed RAGE at their surface. Time course studies of annexin V expression revealed that autoreactive T cells in the spleen of B6-MRL Fas lpr/j-RAGE(-/-) mice exhibited a delay in apoptosis and expressed significantly less activated caspase 3 (39.5 ± 4.3%) than T cells in B6-MRL Fas lpr/j mice (65.5 ± 5.2%) or wild-type mice (75.3 ± 2.64%) (p = 0.02). We conclude that the deletion of RAGE in B6-MRL Fas lpr/j mice promotes the accumulation of autoreactive CD3(+)B220(+)CD4(-)CD8(-) T cells, therefore exacerbating lymphoproliferative syndrome, autoimmunity, and organ injury. This suggests that RAGE rescues the apoptosis of T lymphocytes when the death receptor Fas/CD95 is dysfunctional.

  15. Glucagon-like peptide-1 receptor agonist inhibits asymmetric dimethylarginine generation in the kidney of streptozotocin-induced diabetic rats by blocking advanced glycation end product-induced protein arginine methyltranferase-1 expression.

    PubMed

    Ojima, Ayako; Ishibashi, Yuji; Matsui, Takanori; Maeda, Sayaka; Nishino, Yuri; Takeuchi, Masayoshi; Fukami, Kei; Yamagishi, Sho-ichi

    2013-01-01

    Advanced glycation end products (AGEs) and their receptor (RAGE) play a role in diabetic nephropathy. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, contributes to diabetic nephropathy. We have found that glucagon-like peptide-1 (GLP-1) inhibits the AGE-induced inflammatory reactions in endothelial cells. However, effects of GLP-1 on the AGE-RAGE-ADMA axis are unknown. This study examined the effects of GLP-1 on reactive oxygen species (ROS) generation, gene expression of protein arginine methyltransfetase-1 (PRMT-1), an enzyme that mainly generates ADMA, and ADMA levels in human proximal tubular cells. Streptozotocin-induced diabetic rats received continuous i.p. infusion of 0.3 μg of vehicle or 1.5 μg of the GLP-1 analog exendin-4 per kilogram of body weight for 2 weeks. We further investigated whether and how exendin-4 treatment reduced ADMA levels and renal damage in streptozotocin-induced diabetic rats. GLP-1 inhibited the AGE-induced RAGE and PRMT-1 gene expression, ROS, and ADMA generation in tubular cells, which were blocked by small-interfering RNAs raised against GLP-1 receptor. Exendin-4 treatment decreased gene expression of Rage, Prmt-1, Icam-1, and Mcp-1 and ADMA level; reduced urinary excretions of 8-hydroxy-2'-deoxyguanosine and albumin; and improved histopathologic changes of the kidney in diabetic rats. Our present study suggests that GLP-1 receptor agonist may inhibit the AGE-RAGE-mediated ADMA generation by suppressing PRMT-1 expression via inhibition of ROS generation, thereby protecting against the development and progression of diabetic nephropathy.

  16. Advanced glycation end products induce endothelial-to-mesenchymal transition via downregulating Sirt 1 and upregulating TGF-β in human endothelial cells.

    PubMed

    He, Wei; Zhang, Jian; Gan, Tian-yi; Xu, Guo-jun; Tang, Bao-peng

    2015-01-01

    In the present study, we examined the advanced glycation end products- (AGEs-) induced endothelial-to-mesenchymal transition (EndMT) in human umbilical vein endothelial cells (HUVECs). Results demonstrated that AGE-BSAs significantly reduced the cluster of differentiation 31 (CD 31) expression, whereas they promoted the expression of fibroblast-specific protein-1 (FSP-1), α-smooth muscle antibody (α-SMA), and collagen I at both mRNA and protein levels in HUVECs. And the AGE-BSAs also promoted the receptors for AGEs (RAGEs) and receptor I for TGF-β (TGFR I) markedly with a dose dependence, whereas the Sirt 1 was significantly downregulated by the AGE-BSA at both mRNA and protein levels. Moreover, the Sirt 1 activity manipulation with its activator, resveratrol (RSV), or its inhibitor, EX527, markedly inhibited or ameliorated the AGE-mediated TGF-β upregulation. And the manipulated Sirt 1 activity positively regulated the AGE-induced CD31, whereas it negatively regulated the AGE-induced FSP-1. Thus, Sirt 1 was confirmed to regulate the AGE-induced EndMT via TGF-β. In summary, we found that AGE-BSA induced EndMT in HUVECs via upregulating TGF-β and downregulating Sirt 1, which also negatively regulated TGF-β in the cell. This study implied the EndMT probably as an important mechanism of AGE-induced cardiovascular injury.

  17. Development, relative validity, and reliability of a food frequency questionnaire for a case-control study on dietary advanced glycation end products and diabetes complications.

    PubMed

    Luevano-Contreras, Claudia; Durkin, Taylor; Pauls, Maria; Chapman-Novakofski, Karen

    2013-12-01

    Dietary advanced glycation end products (dAGEs) could be involved on diabetes complications, yet their quantification is not standardized. The objective of this study was to design a food frequency questionnaire (FFQ) for dAGEs, and to assess its reliability and validity. For the design, data from 30 subjects was used. The final instrument had 90 food items. To measure reliability and validity, 20 participants with type 2 diabetes filled out twice the FFQ (FFQ-T1, FFQ-T2) and 7-day food records (7-dFR). The Shrout-Fleiss coefficient was 0.98 showing good reliability. For validation, the results for the weighted kappa were 0.55 (moderate agreement) for FFQ-T1 and 0.64 (good agreement) for FFQ-T2, and 75% and 80% of subjects respectively were correctly classified into tertiles; Bland-Altman graphics showed no systematic bias. This FFQ is comparable to 7-dFR for measuring dAGEs. To our knowledge, this is the first questionnaire designed to measure specifically dAGEs.

  18. Expression of the receptor for advanced glycation end products, a target for high mobility group box 1 protein, and its role in chronic recalcitrant rhinosinusitis with nasal polyps.

    PubMed

    Dzaman, Karolina; Szczepanski, Miroslaw J; Molinska-Glura, Marta; Krzeski, Antoni; Zagor, Mariola

    2015-06-01

    A receptor for advanced glycation end products (RAGE) and its ligand high mobility group box 1 (HMGB1) protein has been linked to several chronic diseases, and acts as a trigger for inflammation signaling. Here, we study RAGE and HMGB1 expression in chronic, recalcitrant rhinosinusitis with nasal polyps (CRSwNP) to determine its potential clinical significance, i.e., disease recurrence and severity. RAGE and HMGB1 expression in CRSwNP was evaluated by immunohistochemistry in epithelial cells of fresh sinonasal mucosa samples obtained from the patients diagnosed with recalcitrant CRSwNP (n = 25) and normal control mucosa (NC) (n = 26). RAGE and HMGB1 expression levels in tissues were correlated with disease severity assessed by nasal endoscopy, CT scan, number of previous sinus surgeries, allergy status and nasosinusal microbiology. RAGE and HMGB1 were moderately or strongly expressed in CRSwNP tissue. No or weak RAGE expression was found in NC. HMGB1 was equally strongly expressed in NC. We observed a strong correlation between RAGE and disease severity, recurrence, undergone operations, asthma and aspirin exacerbated respiratory disease (AERD). Elevated RAGE expression is associated with increased disease severity, as well as allergy and AERD in patients with recalcitrant CRSwNP. It is possible that the explanation for recurrent CRSwNP pathogenesis might be related to RAGE overexpression with subsequent sinus mucosa hyperproliferation, necessitating several operations.

  19. Early expression of the receptor for advanced glycation end products in a toxic model produced by 6-hydroxydopamine in the rat striatum.

    PubMed

    Serratos, Iris N; Castellanos, Pilar; Pastor, Nina; Millán-Pacheco, César; Colín-González, Ana Laura; Rembao, Daniel; Pérez-Montfort, Ruy; Cabrera, Nallely; Sánchez-García, Aurora; Gómez, Isabel; Rangel-López, Edgar; Santamaria, Abel

    2016-04-05

    The receptor for advanced glycation end products (RAGE) is commonly involved in different neurodegenerative and inflammatory disorders. The cellular signaling associated to RAGE activation may occur upon binding to different ligands. In this study we investigated whether the toxic model produced by 6-hydroxydopamine (6-OHDA) in rats comprises early noxious responses related to RAGE-mediated signaling cascades. In order to explore a possible interaction between 6-OHDA and RAGE, affinity parameters of RAGE with 6-OHDA were estimated by different means. The possible binding sites of 6-OHDA with the VC1 homodimer for both rat and human RAGE were also modeled. Our results show that the striatal infusion of 6-OHDA recruits RAGE upregulation, as evidenced by an early expression of the receptor. 6-OHDA was also found to bind the VC1 homodimer, although its affinity was moderate when compared to other ligands. This work contributes to the understanding of the role of RAGE activation for 6-OHDA-induced neurotoxicity.

  20. Accumulation of argpyrimidine, a methylglyoxal-derived advanced glycation end product, increases apoptosis of lens epithelial cells both in vitro and in vivo.

    PubMed

    Kim, Junghyun; Kim, Ohn Soon; Kim, Chan-Sik; Sohn, Eunjin; Jo, Kyuhyung; Kim, Jin Sook

    2012-02-29

    The formation of advanced glycation end products (AGEs) has been considered to be a potential causative factor of injury to lens epithelial cells (LECs). Damage of LECs is believed to contribute to cataract formation. The purpose of this study was to investigate the cytotoxic effect of AGEs on LECs both in vitro and in vivo. We examined the accumulation of argpyrimidine, a methylglyoxal-derived AGE, and the expression of apoptosis-related molecules including nuclear factor- kappaB (NF-κB), Bax, and Bcl-2 in the human LEC line HLE-B3 and in cataractous lenses of Zucker diabetic fatty (ZDF) rats, an animal model of type 2 diabetes. In cataractous lenses from twenty-oneweek- old ZDF rats, LEC apoptosis was markedly increased, and the accumulation of argpyrimidine as well as subsequent activation of NF-κB in LECs were significantly enhanced. The ratio of Bax to Bcl-2 protein levels was also increased. In addition, the accumulation of argpyrimidine triggered apoptosis in methylglyoxal- treated HLE-B3 cells. However, the presence of pyridoxamine (an AGEs inhibitor) and pyrrolidine dithiocarbamate (a NF-κB inhibitor) prevented apoptosis in HLE-B3 cells through the inhibition of argpyrimidine formation and the blockage of NF-κB nuclear translocalization, respectively. These results suggest that the cellular accumulation of argpyrimidine in LECs is NF-κB-dependent and pro-apoptotic.

  1. Soluble Receptor for Advanced Glycation End Product Ameliorates Chronic Intermittent Hypoxia Induced Renal Injury, Inflammation, and Apoptosis via P38/JNK Signaling Pathways

    PubMed Central

    Wu, Xu; Gu, Wenyu; Lu, Huan; Liu, Chengying; Yu, Biyun; Xu, Hui; Tang, Yaodong

    2016-01-01

    Obstructive sleep apnea (OSA) associated chronic kidney disease is mainly caused by chronic intermittent hypoxia (CIH) triggered tissue damage. Receptor for advanced glycation end product (RAGE) and its ligand high mobility group box 1 (HMGB1) are expressed on renal cells and mediate inflammatory responses in OSA-related diseases. To determine their roles in CIH-induced renal injury, soluble RAGE (sRAGE), the RAGE neutralizing antibody, was intravenously administered in a CIH model. We also evaluated the effect of sRAGE on inflammation and apoptosis. Rats were divided into four groups: (1) normal air (NA), (2) CIH, (3) CIH+sRAGE, and (4) NA+sRAGE. Our results showed that CIH accelerated renal histological injury and upregulated RAGE-HMGB1 levels involving inflammatory (NF-κB, TNF-α, and IL-6), apoptotic (Bcl-2/Bax), and mitogen-activated protein kinases (phosphorylation of P38, ERK, and JNK) signal transduction pathways, which were abolished by sRAGE but p-ERK. Furthermore, sRAGE ameliorated renal dysfunction by attenuating tubular endothelial apoptosis determined by immunofluorescence staining of CD31 and TUNEL. These findings suggested that RAGE-HMGB1 activated chronic inflammatory transduction cascades that contributed to the pathogenesis of the CIH-induced renal injury. Inhibition of RAGE ligand interaction by sRAGE provided a therapeutic potential for CIH-induced renal injury, inflammation, and apoptosis through P38 and JNK pathways. PMID:27688824

  2. Phenolic acids inhibit the formation of advanced glycation end products in food simulation systems depending on their reducing powers and structures.

    PubMed

    Chen, Hengye; Virk, Muhammad Safiullah; Chen, Fusheng

    2016-06-01

    The concentration of advanced glycation end products (AGEs) in foods, which are formed by Maillard reaction, has demonstrated as risk factors associated with many chronic diseases. The AGEs inhibitory activities of five common phenolic acids (protocatechuic acid, dihydroferulic acid, p-coumaric acid, p-hydroxybenzoic acid and salicylic acid) with different chemical properties had been investigated in two food simulation systems (glucose-bovine serum albumin (BSA) and oleic acid-BSA). The results substantiated that the AGEs inhibitory abilities of phenolic acids in the oleic acid BSA system were much better than the glucose-BSA system for their strong reducing powers and structures. Among them, dihydrogenferulic acid showed strong inhibition of AGEs formation in oleic acid-BSA system at 0.01 mg/mL compared to nonsignificant AGEs inhibitory effect in oleic acid-BSA system at 10-fold higher concentration (0.1 mg/mL). This study suggests that edible plants rich in phenolic acids may be used as AGEs inhibitor during high-fat cooking.

  3. Positive association of circulating levels of advanced glycation end products (AGEs) with pigment epithelium-derived factor (PEDF) in a general population.

    PubMed

    Yamagishi, Sho-Ichi; Matsui, Takanori; Adachi, Hisashi; Takeuchi, Masayoshi

    2010-02-01

    We have recently found that serum levels of pigment epithelium-derived factor (PEDF), a glycoprotein with anti-oxidative and anti-inflammatory properties, are elevated in proportion to the accumulation of the number of the components of the metabolic syndrome. Since formation and accumulation of advanced glycation end products (AGEs) progress under the metabolic syndrome and that PEDF could inhibit the AGE-elicited tissue damage, it is conceivable that PEDF levels may be increased as a counter-system against AGEs in patients with the metabolic syndrome. However, correlation between circulating levels of AGEs and PEDF in humans remains to be elucidated. In this study, we investigated the relationship between serum AGE and PEDF levels in a general population and examined the effects of AGEs on PEDF gene expression in vitro. One hundred ninety-six Japanese subjects in a general population underwent a complete history and physical examination, determination of blood chemistries, including serum levels of AGEs and PEDF. In multiple regression analyses, creatinine, body mass index, triglycerides, AGEs and insulin were independently correlated with serum PEDF levels. AGEs dose-dependently increased PEDF gene expression in cultured adipocytes and liver cells. Our present study demonstrated first that circulating AGEs were one of the independent correlates of serum levels of PEDF. Adipose tissue and liver may be target organs for the AGE-induced PEDF overexpression in humans. Serum PEDF levels may be elevated in response to circulating AGEs as a counter-system against the AGE-elicited tissue damage.

  4. Altered Expression of NF- κ B and SP1 after Exposure to Advanced Glycation End-Products and Effects of Neurotrophic Factors in AGEs Exposed Rat Retinas.

    PubMed

    Bikbova, Guzel; Oshitari, Toshiyuki; Baba, Takayuki; Yamamoto, Shuichi

    2015-01-01

    To determine the effect of advanced glycation end-products (AGEs) on neurite regeneration, and also to determine the regenerative effects of different neurotrophic factors (NTFs) on rat retinal explants, the retinas of SD rats were cultured in three-dimensional collagen gels and incubated in 6 types of media: (1) serum-free control culture media; (2) 100 μg/mL AGEs-BSA media; (3) AGEs-BSA + 100 ng/mL neurotrophin-4 (NT-4) media; (4) AGEs-BSA + 100 ng/mL hepatocyte growth factor media; (5) AGEs-BSA + 100 ng/mL glial cell line-derived neurotrophic factor media; or (6) AGEs-BSA + 100 µM tauroursodeoxycholic acid media. After 7 days, the number of regenerating neurites was counted. The explants were immunostained for nuclear factor-κB (NF-κB) and specificity protein 1 (SP1). Statistical analyses were performed by one-way ANOVA. In retinas incubated with AGEs, the numbers of neurites were fewer than in control. All of the NTFs increased the number of neurites, and the increase was more significant in the NT-4 group. The number of NF-κB and SP1 immunopositive cells was higher in retinas exposed to AGEs than in control. All of the NTFs decreased the number of NF-κB immunopositive cells but did not significantly affect SP1 expression. These results demonstrate the potential of the NTFs as axoprotectants in AGEs exposed retinal neurons.

  5. High dietary advanced glycation end products are associated with poorer spatial learning and accelerated Aβ deposition in an Alzheimer mouse model.

    PubMed

    Lubitz, Irit; Ricny, Jan; Atrakchi-Baranes, Dana; Shemesh, Chen; Kravitz, Efrat; Liraz-Zaltsman, Sigal; Maksin-Matveev, Anna; Cooper, Itzik; Leibowitz, Avshalom; Uribarri, Jaime; Schmeidler, James; Cai, Weijing; Kristofikova, Zdena; Ripova, Daniela; LeRoith, Derek; Schnaider-Beeri, Michal

    2016-04-01

    There is growing evidence of the involvement of advanced glycation end products (AGEs) in the pathogenesis of neurodegenerative processes including Alzheimer's disease (AD) and their function as a seed for the aggregation of Aβ, a hallmark feature of AD. AGEs are formed endogenously and exogenously during heating and irradiation of foods. We here examined the effect of a diet high in AGEs in the context of an irradiated diet on memory, insoluble Aβ42 , AGEs levels in hippocampus, on expression of the receptor for AGEs (RAGE), and on oxidative stress in the vasculature. We found that AD-like model mice on high-AGE diet due to irradiation had significantly poorer memory, higher hippocampal levels of insoluble Aβ42 and AGEs as well as higher levels of oxidative stress on vascular walls, compared to littermates fed an isocaloric diet. These differences were not due to weight gain. The data were further supported by the overexpression of RAGE, which binds to Aβ42 and regulates its transport across the blood-brain barrier, suggesting a mediating pathway. Because exposure to AGEs can be diminished, these insights provide an important simple noninvasive potential therapeutic strategy for alleviating a major lifestyle-linked disease epidemic.

  6. Glycolaldehyde-derived advanced glycation end products (glycol-AGEs)-induced vascular smooth muscle cell dysfunction is regulated by the AGES-receptor (RAGE) axis in endothelium.

    PubMed

    Nam, Mi-Hyun; Son, Won-Rak; Lee, Young Sik; Lee, Kwang-Won

    Advanced glycation end-products (AGEs) are involved in the development of vascular smooth muscle cell (VSMC) dysfunction and the progression of atherosclerosis. However, AGEs may indirectly affect VSMCs via AGEs-induced signal transduction between monocytes and human umbilical endothelial cells (HUVECs), rather than having a direct influence. This study was designed to elucidate the signaling pathway underlying AGEs-RAGE axis influence on VSMC dysfunction using a co-culture system with monocytes, HUVECs and VSMCs. AGEs stimulated production of reactive oxygen species and pro-inflammatory mediators such as tumor necrosis factor-α and interleukin-1β via extracellular-signal-regulated kinases phosphorylation and nuclear factor-κB activation in HUVECs. It was observed that AGEs-induced pro-inflammatory cytokines increase VSMC proliferation, inflammation and vascular remodeling in the co-culture system. This result implies that RAGE plays a role in AGEs-induced VSMC dysfunction. We suggest that the regulation of signal transduction via the AGEs-RAGE axis in the endothelium can be a therapeutic target for preventing atherosclerosis.

  7. Cerebral Ketone Body Oxidation Is Facilitated by a High Fat Diet Enriched with Advanced Glycation End Products in Normal and Diabetic Rats

    PubMed Central

    de Assis, Adriano M.; da Silva, Jussemara S.; Rech, Anderson; Longoni, Aline; Nonose, Yasmine; Repond, Cendrine; de Bittencourt Pasquali, Matheus A.; Moreira, José C. F.; Souza, Diogo O.; Pellerin, Luc

    2016-01-01

    Diabetes mellitus (DM) causes important modifications in the availability and use of different energy substrates in various organs and tissues. Similarly, dietary manipulations such as high fat diets also affect systemic energy metabolism. However, how the brain adapts to these situations remains unclear. To investigate these issues, control and alloxan-induced type I diabetic rats were fed either a standard or a high fat diet enriched with advanced glycation end products (AGEs) (HAGE diet). The HAGE diet increased their levels of blood ketone bodies, and this effect was exacerbated by DM induction. To determine the effects of diet and/or DM induction on key cerebral bioenergetic parameters, both ketone bodies (β-hydroxybutyric acid) and lactate oxidation were measured. In parallel, the expression of Monocarboxylate Transporter 1 (MCT1) and 2 (MCT2) isoforms in hippocampal and cortical slices from rats submitted to these diets was assessed. Ketone body oxidation increased while lactate oxidation decreased in hippocampal and cortical slices in both control and diabetic rats fed a HAGE diet. In parallel, the expression of both MCT1 and MCT2 increased only in the cerebral cortex in diabetic rats fed a HAGE diet. These results suggest a shift in the preferential cerebral energy substrate utilization in favor of ketone bodies in animals fed a HAGE diet, an effect that, in DM animals, is accompanied by the enhanced expression of the related transporters. PMID:27877108

  8. Modulation of advanced glycation end products by candesartan in patients with diabetic kidney disease--a dose-response relationship study.

    PubMed

    Saha, Sandeep A; LaSalle, Brian K; Clifton, G Dennis; Short, Robert A; Tuttle, Katherine R

    2010-01-01

    Advanced glycation end products (AGEs) are proinflammatory mediators implicated in the pathogenesis of diabetic kidney disease (DKD). In this study, dose-dependent effects of angiotensin receptor blockade on urinary AGEs were evaluated in patients with DKD. Patients with type 2 diabetes and proteinuria ≥500 mg/d (n = 11) were compared with diabetic controls without DKD (n = 10) and normal controls (n = 11). After a 2-week washout period, DKD participants were treated with candesartan doses progressively increasing from 8, 16, 32, to 64 mg/d every 3 weeks for a total of 12 weeks. Other antihypertensive agents were adjusted to maintain stable blood pressure. At baseline and after each dosing period, blood pressure measurements and 24-hour urine collections were obtained. Urinary carboxymethyl lysine, an AGE biomarker, was reduced over the 12-week dose escalation protocol (r = 0.38, P = 0.01) in DKD participants. Creatinine clearance increased slightly, but albuminuria was unaffected by candesartan administration. Baseline urinary transforming growth factor-β₁ excretion was lower in DKD participants than in controls and did not change during the study period. Reducing kidney exposure to AGEs may be a mechanism of protection by angiotensin receptor blockade in DKD. AGEs may also impact the diabetic kidney through mechanisms independent of transforming growth factor-β₁.

  9. Receptor for advanced glycation end products involved in lung ischemia reperfusion injury in cardiopulmonary bypass attenuated by controlled oxygen reperfusion in a canine model.

    PubMed

    Rong, Jian; Ye, Sheng; Liang, Meng-ya; Chen, Guang-xian; Liu, Hai; Zhang, Jin-Xin; Wu, Zhong-kai

    2013-01-01

    Controlled oxygen reperfusion could protect the lung against ischemia-reperfusion injury in cardiopulmonary bypass (CPB) by downregulating high mobility group box 1 (HMGB1), a high affinity receptor of HMGB1. This study investigated the effect of controlled oxygen reperfusion on receptor for advanced glycation end products (RAGE) expression and its downstream effects on lung ischemia-reperfusion injury. Fourteen canines received CPB with 60 minutes of aortic clamping and cardioplegic arrest followed by 90 minutes of reperfusion. Animals were randomized to receive 80% FiO2 during the entire procedure (control group) or to a test group receiving a controlled oxygen reperfusion protocol. Pathologic changes in lung tissues, RAGE expression, serum interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were evaluated. The lung pathologic scores after 25 and 90 minutes of reperfusion were significantly lower in the test group compared with the control group (p < 0.001). RAGE expression, TNF-α, and IL-6 were downregulated by controlled oxygen treatment (p < 0.001). RAGE might be involved in the lung ischemia-reperfusion injury in canine model of CPB, which was downregulated by controlled oxygen reperfusion.

  10. Ghrelin protects human umbilical vein endothelial cells against advanced glycation end products-induced apoptosis via NO/cGMP signaling

    PubMed Central

    Li, Pengjie; Liu, Ying; Xiang, Ying; Lin, Miao; Gao, Jinling

    2015-01-01

    Objectives: The aim of this study was to investigate the intracellular mechanism involved in the anti-apoptotic effect of ghrelin on human umbilical vein endothelial cells (HUVECs). Methods: HUVECs were pretreated with ghrelin before exposure to 200 μg/ml advanced glycation end products (AGEs)-BSA for 48 h. Cell viability and apoptosis were determined by MTT assay and Annexin V/PI staining. Intracellular cGMP levels evaluation and cGMP analogs were employed to explore possible mechanisms. Results: The inhibitory effect on AGEs induced HUVECs apoptosis could be exerted by ghrelin and co-incubation with growth hormone secretagogue receptor (GHSR)-1a antagonist [D-Lys3]-GHRP-6 abolished this inhibition. Decreased cGMP level in AGEs induced HUVECs apoptosis was restored by ghrelin pretreatment and abolished by [D-Lys3]-GHRP-6 co-incubation. cGMP analogs (8 Br-cGMP and DB-cGMP) pretreatment also exhibited inhibitory effect on AGEs induced HUVECs apoptosis. Conclusions: Our results demonstrated that ghrelin produces a protective effect on HUVECs through GHS-R1a and cGMP/NO signaling pathway mediates the effect of ghrelin. These observations suggest a novel intracellular mechanism in the process of AGEs induced HUVECs apoptosis. PMID:26629013

  11. 2016 ATVB Plenary Lecture: Receptor for Advanced Glycation Endproducts and Implications for the Pathogenesis an Treatment of Cardiometabolic Disorders: Spotlight on the Macrophage.

    PubMed

    Schmidt, Ann Marie

    2017-04-01

    The receptor for advanced glycation endproducts (RAGE) interacts with a unique repertoire of ligands that form and collect in the tissues and circulation in diabetes mellitus, aging, inflammation, renal failure, and obesity. RAGE is expressed on multiple cell types linked to tissue perturbation in these settings. This brief review focuses on the role of RAGE in monocytes/macrophages and how RAGE ligand engagement on these cells mediates seminal changes in monocyte/macrophage migration, oxidative stress, cholesterol efflux, and pro- versus anti-inflammatory cues that signal to tissue damage. Studies using mice devoid of Ager (gene encoding RAGE) or pharmacological antagonists of RAGE are protective in animal models of diabetes mellitus, atherosclerosis, and high-fat diet-induced obesity, in least in part through key roles in monocytes/macrophages. RAGE signal transduction requires the interaction of RAGE cytoplasmic domain with the formin, DIAPH1 (diaphanous 1) and novel antagonists of this interaction show significant promise in attenuation of the maladaptive effects of RAGE ligands in cellular and in vivo models. Finally, this brief review discusses evidence for RAGE axis perturbation in human monocytes/macrophages and how tracing RAGE activity in these cells may identify target engagement biomarkers of RAGE antagonism for future clinical trials.

  12. Far-infrared protects vascular endothelial cells from advanced glycation end products-induced injury via PLZF-mediated autophagy in diabetic mice

    PubMed Central

    Chen, Cheng-Hsien; Chen, Tso-Hsiao; Wu, Mei-Yi; Chou, Tz-Chong; Chen, Jia-Rung; Wei, Meng-Jun; Lee, San-Liang; Hong, Li-Yu; Zheng, Cai-Mei; Chiu, I-Jen; Lin, Yuh-Feng; Hsu, Ching-Min; Hsu, Yung-Ho

    2017-01-01

    The accumulation of advanced glycation end products (AGEs) in diabetic patients induces vascular endothelial injury. Promyelocytic leukemia zinc finger protein (PLZF) is a transcription factor that can be activated by low-temperature far-infrared (FIR) irradiation to exert beneficial effects on the vascular endothelium. In the present study, we investigated the influence of FIR-induced PLZF activation on AGE-induced endothelial injury both in vitro and in vivo. FIR irradiation inhibited AGE-induced apoptosis in human umbilical vein endothelial cells (HUVECs). PLZF activation increased the expression of phosphatidylinositol-3 kinases (PI3K), which are important kinases in the autophagic signaling pathway. FIR-induced PLZF activation led to autophagy in HUVEC, which was mediated through the upregulation of PI3K. Immunofluorescence staining showed that AGEs were engulfed by HUVECs and localized to lysosomes. FIR-induced autophagy promoted AGEs degradation in HUVECs. In nicotinamide/streptozotocin-induced diabetic mice, FIR therapy reduced serum AGEs and AGEs deposition at the vascular endothelium. FIR therapy also reduced diabetes-induced inflammatory markers in the vascular endothelium and improved vascular endothelial function. These protective effects of FIR therapy were not found in PLZF-knockout mice. Our data suggest that FIR-induced PLZF activation in vascular endothelial cells protects the vascular endothelium in diabetic mice from AGE-induced injury. PMID:28071754

  13. Clinical Implications of High-mobility Group Box-1 (HMGB1) and the Receptor for Advanced Glycation End-products (RAGE) in Cutaneous Malignancy: A Systematic Review.

    PubMed

    Nguyen, Austin Huy; Detty, Shannon Q; Agrawal, Devendra K

    2017-01-01

    Inflammation and the immune system play a role in the development and progression of melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). The pro-inflammatory and tumor-promoting effects of the high-mobility group box-1 (HMGB1) protein and the receptor for advanced glycation end products (RAGE) have been investigated in these cutaneous malignancies. The clinical implication of these molecules is not fully described. The National Library of Medicine database was searched for articles addressing the clinical relevance of HMGB1 and RAGE in melanoma, BCC, and SCC. This systematic review includes nine articles, with six summarizing RAGE in cutaneous malignancies and three involving HMGB1. RAGE has been found to be up-regulated in SCC lesions, as well as melanoma. Levels of RAGE were highest in stage IV melanomas. Lower levels of soluble RAGE have been associated with poor overall survival in melanoma. Sporadic extracellular expression of HMGB1 was evident in BCC and SCC lesions, which could be released by necrotic tumor cells. HMGB1 was found to be a prognostic marker in melanoma, and HMGB1 levels were elevated in patients who were non-responders to ipilimumab treatment. HMGB1 and RAGE could serve as potential prognostic markers or therapeutic targets in treating melanoma, BCC, and SCC, but further research regarding the clinical utility of the HMGB1-RAGE axis in cutaneous malignancies is warranted.

  14. Green tea epigallocatechin 3-gallate alleviates hyperglycemia and reduces advanced glycation end products via nrf2 pathway in mice with high fat diet-induced obesity.

    PubMed

    Sampath, Chethan; Rashid, Muhammed Raihan; Sang, Shengmin; Ahmedna, Mohamed

    2017-03-01

    Epigallocatechin 3-gallate (EGCG) from green tea may reduce plasma glucose and alleviate complications of diabetes by attenuating advanced glycation end products (AGEs) formation. We hypothesized that EGCG would mitigate AGEs formation via activating the nuclear factor erythroid-2-related-factor-2 (Nrf2) pathway in a mouse model of high fat diet-induced obesity. Dietary EGCG was tested in C57BL/6 mice that were placed on a high-fat diet with or without ECGC for 17 weeks and compared to a control group placed on low-fat diet for the same period. Weight gain and fasting blood glucose were measured throughout the study duration. Supplementation of high fat diet with dietary EGCG significantly reduced weight gain, plasma glucose, insulin level, liver and kidney weight. EGCG administration also decreased the levels of AGEs in both plasma and liver while inhibiting the receptor for AGE (RAGE) expression of, activating Nrf2 and enhancing GSH/GSSG ratio compared to mice on high fat diet without added EGCG. This study demonstrated that EGCG has the potential to help control hyperglycemia, reduce weight, and alleviate diabetes complications.

  15. Long-term administration of advanced glycation end-product stimulates the activation of NLRP3 inflammasome and sparking the development of renal injury.

    PubMed

    Yeh, Wan-Ju; Yang, Hsin-Yi; Pai, Man-Hui; Wu, Chi-Hao; Chen, Jiun-Rong

    2017-01-01

    The accumulation of advanced glycation end-products (AGEs) and the enhanced interaction of AGE with their cellular receptor (RAGE) have been implicated in the progression of chronic kidney disease. The purpose of this study was to examine whether the AGE/RAGE-induced nephrotoxic effects are associated with inflammasome activation and endothelial dysfunction. Chronic renal injury was examined in BALB/c mice by the long-term administration of carbonyl-AGE for 16 weeks. Endothelial dysfunction was detected by measuring the number of circulating endothelial progenitor cells (EPCs) and the levels of nitric oxide synthase (eNOS) and nitric oxide (NO) in kidneys. Results showed that administration of methylglyoxal-bovine serum albumin (MG-BSA) AGE accelerated renal MG, carboxyethyl lysine, carboxymethyl lysine and malondialdehyde formation and, in parallel, the levels of serum creatinine and blood urea nitrogen (BUN) were significantly increased. Expression of RAGE and NLRP3 inflammasome-related proteins (TXNIP, NLRP3, procaspase-1 and caspase-1) and IL (interleukin)-1β secretion were upregulated, whereas the levels of EPCs, eNOS and NO were lower in MG-BSA-treated mice. This induction by MG-BSA was significantly inhibited by RAGE antagonist. Our results firstly reveal a possible mechanism of AGE-mediated renal dysfunction upon NLRP3 inflammasome activation. Therapeutic blockade of RAGE may ameliorate renal and endothelial functions in subjects under high AGE burden.

  16. Lower concentrations of receptor for advanced glycation end products and epiregulin in amniotic fluid correlate to chemically induced cleft palate in mice.

    PubMed

    Wang, Xinhuan; Zhu, Jingjing; Fang, Yanjun; Bian, Zhuan; Meng, Liuyan

    2017-02-28

    This study investigated the correlation between differentially expressed proteins in amniotic fluid (AF) and cleft palate induced by all-trans retinoic acid (atRA), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in mice. Seven proteins were differentially expressed at embryonic day (E) 16.5 in atRA and control groups as revealed by label-based mouse antibody array. Enzyme-linked immunosorbent assay was further used to detect the expression levels of these proteins in AF from E13.5 to E16.5 in atRA, TCDD, and control groups. The cleft palate groups showed lower concentrations of receptor for advanced glycation end products (RAGE) and epiregulin at E16.5. RAGE immunostaining obviously decreased in palatal tissue sections obtained from E14.5 to E16.5 in the cleft palate groups as revealed by immunohistochemistry. These findings indicate that reduced levels of RAGE and epiregulin in AF are correlated to chemically induced cleft palate in mice.

  17. Inhibitory Potential of Constituents from Osmanthus fragrans and Structural Analogues Against Advanced Glycation End Products, α-Amylase, α-Glucosidase, and Oxidative Stress.

    PubMed

    Yang, Ji-Yeon; Park, Jun-Hwan; Chung, Namhyun; Lee, Hoi-Seon

    2017-03-31

    Inhibition of α-amylase and α-glucosidase, advanced glycation end products (AGEs) formation, and oxidative stress by isolated active constituents of Osmanthus fragrans flowers (9,12-octadecadienoic acid and 4-(2,6,6-trimethyl-1-cyclohexenyl)-3-buten-2-one) and their structural analogues were evaluated. 9,12-Octadecadienoic acid was 10.02 and 22.21 times more active against α-amylase and α-glucosidase, respectively, than acarbose and ascorbic acid, followed by 9,12,15-octadecatrienoic acid, 9-octadecenoic acid, 4-(2,6,6-trimethyl-1-cyclohexenyl)-3-buten-2-one, 4-(2,6,6-trimethyl-2-cyclohexenyl)-3-buten-2-one, 1-heptadecanecarboxylic acid, and 1-pentadecanecarboxylic acid. Concerning the inhibition of AGEs formation, similar with data for 2,2'-diphenyl-1-picrylhydrazl radical scavenging activities, 9,12-octadecadienoic acid was 3.54 times more active than aminoguanidine, followed by 9,12,15-octadecatrienoic acid, and 9-octadecenoic acid. These results indicate that 4-(2,6,6-trimethyl-1-cyclohexenyl)-3-buten-2-one, 9,12-octadecadienoic acid and their analogues inhibit α-amylase and α-glucosidase, AGEs formation, and oxidative stress have potential value in alleviating diabetic pathological conditions.

  18. ER stress is associated with reduced ABCA-1 protein levels in macrophages treated with advanced glycated albumin - reversal by a chemical chaperone.

    PubMed

    Castilho, Gabriela; Okuda, Ligia S; Pinto, Raphael S; Iborra, Rodgiro T; Nakandakare, Edna R; Santos, Celio X; Laurindo, Francisco R; Passarelli, Marisa

    2012-07-01

    ATP-binding cassette transporter A1 mediates the export of excess cholesterol from macrophages, contributing to the prevention of atherosclerosis. Advanced glycated albumin (AGE-alb) is prevalent in diabetes mellitus and is associated with the development of atherosclerosis. Independently of changes in ABCA-1 mRNA levels, AGE-alb induces oxidative stress and reduces ABCA-1 protein levels, which leads to macrophage lipid accumulation. These metabolic conditions are known to elicit endoplasmic reticulum (ER) stress. We sought to determine if AGE-alb induces ER stress and unfolded protein response (UPR) in macrophages and how disturbances to the ER could affect ABCA-1 content and cholesterol efflux in macrophages. AGE-alb induced a time-dependent increase in ER stress and UPR markers. ABCA-1 content and cellular cholesterol efflux were reduced by 33% and 47%, respectively, in macrophages treated with AGE-alb, and both were restored by treatment with 4-phenyl butyric acid (a chemical chaperone that alleviates ER stress), but not MG132 (a proteasome inhibitor). Tunicamycin, a classical ER stress inductor, also impaired ABCA-1 expression and cholesterol efflux (showing a decrease of 61% and 82%, respectively), confirming the deleterious effect of ER stress in macrophage cholesterol accumulation. Glycoxidation induces macrophage ER stress, which relates to the reduction in ABCA-1 and in reverse cholesterol transport, endorsing the adverse effect of macrophage ER stress in atherosclerosis. Thus, chemical chaperones that alleviate ER stress may represent a useful tool for the prevention and treatment of atherosclerosis in diabetes.

  19. Involvement of Na{sup +}/H{sup +} exchanger 1 in advanced glycation end products-induced proliferation of vascular smooth muscle cell

    SciTech Connect

    Wu Shujin; Song Tao; Zhou Shouhong; Liu Yuhui; Chen Gengrong; Huang Ningjiang; Liu Liying

    2008-10-24

    In this present study, we examined the role of Na{sup +}/H{sup +} exchanger 1 (NHE1) in the cultured rat vascular smooth muscle cell (VSMC) proliferation induced by advanced glycation end products (AGEs). AGEs significantly increased the [{sup 3}H] thymidine incorporation of VSMC. Cariporide, an NHE1 inhibitor, dose-dependently attenuated the AGEs-induced increase in cell DNA synthesis. Thus the effect of AGEs on NHE1 activity was next examined. The cariporide-dependent intracellular pH (pH{sub i}) was significantly increased after 24 h exposure to AGEs (10 {mu}g/ml). The direct AGEs-induced NHE1 activation was measured by the Na{sup +}-dependent intracellular pH recovery from intracellular acidosis. AGEs can increase the NHE1 activity in a time- and concentration-dependent manner. Inhibition of either the receptor for AGEs (RAGE) by anti-RAGE or mitogen-activated protein kinases (MAPK) by PD98059 reversed the effect of AGEs on NHE1 activity. Reverse transcription (RT)-PCR analysis revealed that AGEs dose-dependently increased NHE1 mRNA at 24 h. These findings demonstrate NHE1 is required for in AGEs-induced proliferation of VSMC, and AGEs increase NHE1 activity via the MAPK pathway.

  20. Inhibition of the Receptor for Advanced Glycation End-Products (RAGE) Attenuates Neuroinflammation While Sensitizing Cortical Neurons Towards Death in Experimental Subarachnoid Hemorrhage.

    PubMed

    Li, Hua; Yu, Jia-Sheng; Zhang, Ding-Ding; Yang, Yi-Qing; Huang, Li-Tian; Yu, Zhuang; Chen, Ru-Dong; Yang, Hong-Kuan; Hang, Chun-Hua

    2017-01-01

    Subarachnoid hemorrhage (SAH) is a threatening and devastating neurological insult with high mortality and morbidity rates. Despite considerable efforts, the underlying pathophysiological mechanisms are still poorly understood. The receptor for advanced glycation end products (RAGE) is a multiligand receptor that has been implicated in various pathological conditions. We previously showed that RAGE was upregulated and may be involved in pathophysiology of SAH. In the current study, we investigated its potential role in SAH. We found that the upregulation of RAGE after SAH was NF-κB-dependent positive feedback regulation. Further, pharmacological inhibition of RAGE attenuated neuroinflammation, indicating a possible contributive role of RAGE in inflammation-associated brain injury after SAH. Conversely, however, inhibition of RAGE sensitized neurons, exacerbating cell death, which correlated with augmented apoptosis and diminished autophagy, suggesting that activation of RAGE may protect against SAH-induced neuronal injury. Furthermore, we demonstrate that inhibition of RAGE significantly reduced brain edema and improved neurological function at day 1 but not at day 3 post-SAH. Taken together, these results suggest that RAGE exerts dual role after SAH. Our findings also suggest caution should be exercised in setting RAGE-targeted treatment for SAH.

  1. Advanced glycation end products interfere with gastric smooth muscle contractile marker expression via the AGE/RAGE/NF-κB pathway.

    PubMed

    Yu, Ting; Zheng, Yongping; Wang, Yun; Xiong, Wenjie; Lin, Lin

    2017-02-01

    Excessive production of advanced glycation end products (AGE) has been implicated in the pathogenesis of diabetic complications. Smooth muscle (SM) phenotype transition is involved in diabetes-associated gastric motility dysfunction. We investigated whether AGE interfere with gastric antral SM contractile marker expression. Sixteen Sprague-Dawley rats were randomly divided into control and streptozotocin-induced diabetic groups. Sixteen weeks after streptozotocin administration, gastric antral SM strip contractility in the groups were measured. The gastric tissue expression of AGE was tested. Primary cultured gastric smooth muscle cells (SMCs) were used in complementary in vitro studies. In the presence and absence of AGE, SMCs were transfected with myocardin plasmid or treated with nuclear factor-κB (NF-κB) inhibitor or anti-RAGE antibody. Diabetic rats showed weakness of SM strip contractility and decreased expression of SM contractile marker genes (myosin heavy chains [MHC], α-actin, calponin) as compared with the control group. Gastric antral SM layer Nε-(carboxymethyl) lysine (CML) level, the major AGE compound, were increased in the diabetic rats. AGE downregulated SM contractile markers and myocardin expression in a concentration-dependent manner. Myocardin overexpression prevented these results. AGE treatment activated NF-κB in SMCs. The NF-κB inhibitor BAY 11-7082 and anti-RAGE antibody blocked the effects of AGE on myocardin downregulation. AGE may induce the development of gastric dysmotility by downregulating SM contractile proteins and myocardin expression via the AGE/RAGE/NF-κB pathway.

  2. Expression of the Receptor for Advanced Glycation End Products in Epicardial Fat: Link with Tissue Thickness and Local Insulin Resistance in Coronary Artery Disease.

    PubMed

    Dozio, Elena; Vianello, Elena; Briganti, Silvia; Lamont, John; Tacchini, Lorenza; Schmitz, Gerd; Corsi Romanelli, Massimiliano Marco

    2016-01-01

    Increased expression of receptor for advanced glycation end products (RAGE) in adipose tissue has been associated with inflammation, adipocyte hypertrophy, and impaired insulin signal. Epicardial adipose tissue (EAT), a visceral fat surrounding the myocardium, is potentially involved in the onset/progression of coronary artery disease (CAD). To date, the role of RAGE in EAT has not been explored much. We examined whether the RAGE expression in EAT was associated with EAT adiposity and metabolic dysfunctions normally found in CAD patients. EAT samples were obtained from 33 patients undergoing open-heart surgery. EAT expression of RAGE, GLUT4, adiponenctin, GLO1, HMGB1, TLR-4, and MyD88 was analyzed by microarray. EAT thickness was quantified by echocardiography. Anthropometric measures and clinical parameters were taken. BMI, HOMA-IR, and LAP indices were calculated. With increasing RAGE expression in EAT we observed increases in EAT thickness, reduced expression of GLUT4, adiponectin, and GLO1, and elevations of HMGB1, TLR-4, and MyD88. There were significant correlations between RAGE and EAT thickness and between RAGE and the genes. LAP was higher in patients with increased RAGE expression. Our data suggest that in CAD patients RAGE may be involved in promoting EAT adiposity and metabolic dysfunction, such as impaired insulin signaling.

  3. Comparative effects of pioglitazone and rosiglitazone on plasma levels of soluble receptor for advanced glycation end products in type 2 diabetes mellitus patients.

    PubMed

    Oz Gul, Ozen; Tuncel, Ercan; Yilmaz, Yusuf; Ulukaya, Engin; Gul, Cuma Bulent; Kiyici, Sinem; Oral, Arzu Yilmaztepe; Guclu, Metin; Ersoy, Canan; Imamoglu, Sazi

    2010-01-01

    Low levels of soluble receptor for advanced glycation end products (sRAGE) have been associated with the occurrence of vascular complications in patients with type 2 diabetes mellitus. Preliminary evidence has suggested that thiazolidinediones have the ability to modulate circulating levels of this molecule in the hyperglycemic milieu. The aim of this pilot study was to assess the differential effect of 2 different thiazolidinediones-pioglitazone and rosiglitazone-on plasma levels of sRAGE in type 2 diabetes mellitus patients. Sixty type 2 diabetes mellitus subjects were randomly assigned to receive pioglitazone (30 mg/d, n = 19), rosiglitazone (4 mg/d, n = 20), or placebo (medical nutrition therapy, n = 21) for 12 weeks. Changes in plasma glucose, glycosylated hemoglobin, insulin resistance (homeostasis model assessment), total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, and sRAGE were evaluated at baseline and after 12 weeks. At 12 weeks, the pioglitazone (P < .001) group had a significant increase from baseline in sRAGE values that was not seen in the medical nutrition therapy and rosiglitazone groups. We conclude that, in type 2 diabetes mellitus patients, pioglitazone-but not rosiglitazone-significantly raised sRAGE, which may contribute to its antiatherogenic effects.

  4. Increased pentosidine, an advanced glycation end product, in serum and synovial fluid from patients with knee osteoarthritis and its relation with cartilage oligomeric matrix protein

    PubMed Central

    Senolt, L; Braun, M; Olejarova, M; Forejtova, S; Gatterova, J; Pavelka, K

    2005-01-01

    Background: Pentosidine, an advanced glycation end product, increasingly accumulates in articular cartilage with age, and contributes to the pathogenesis of osteoarthritis (OA). Increased pentosidine concentrations are associated with inflammatory disorders—for example, rheumatoid arthritis. Objective: To compare pentosidine serum concentrations in patients with knee OA and in healthy volunteers and to determine a relationship between pentosidine and cartilage oligomeric matrix protein (COMP)—a marker of articular cartilage destruction. Methods: Paired serum and synovial fluid samples were obtained by arthrocentesis from 38 patients with knee OA and from 38 healthy volunteers. Pentosidine concentration was measured by reverse phase high performance liquid chromatography with fluorescent detection and COMP was determined by sandwich ELISA. Results: Significantly increased serum pentosidine (p<0.01) and COMP (p<0.05) levels were detected in the patients with OA compared with the control group. Serum pentosidine correlated significantly with synovial fluid pentosidine (p<0.001). Pentosidine in synovial fluid (p<0.05) and in serum (p<0.05) correlated significantly with synovial fluid COMP. Pentosidine and COMP concentrations did not correlate significantly with the radiological stage of the disease. Conclusion: Increased pentosidine serum concentration in patients with OA and its correlation with the cartilage destruction marker COMP in synovial fluid suggests that pentosidine may be important in OA pathology and is a new potential OA marker. PMID:15897309

  5. Clinical use of high mobility group box 1 and the receptor for advanced glycation end products in the prognosis and risk stratification of heart failure: a literature review.

    PubMed

    Marsh, Amanda M; Nguyen, Austin Huy; Parker, Taylor M; Agrawal, Devendra K

    2017-03-01

    Heart failure (HF) is a clinical syndrome that represents the end stage of heart disease and remains the leading cause of morbidity and mortality worldwide. As heart failure mortality rates remain elevated, additional biomarkers that facilitate early detection or risk stratification in HF is of particularly great interest. High mobility group box 1 (HMGB1) and receptor for advanced glycation end products (RAGE) cause the activation of intracellular signaling, gene expression, and production of inflammatory cytokines and have been linked to many inflammatory disease states such as diabetes mellitus and atherosclerosis. Few studies have investigated their role in the pathophysiology of HF and any significant correlation remains uncertain. Review of the available literature discussing HMGB1 and RAGE clinical values as independent prognostic variables in HF resulted in the inclusion of 11 studies, which enrolled a total of 2025 heart failure patients. Overall, the data suggests a statistically significant positive correlation between RAGE and HF, with increasing RAGE levels associated with increasing New York Heart Association (NYHA) functional class of heart failure. HMGB1 correlations were not as extensively studied, but there is evidence that both HMGB1 and RAGE have a definite potential as biomarkers for the prognosis and risk stratification of HF patients.

  6. Interaction of the S100A6 mutant (C3S) with the V domain of the receptor for advanced glycation end products (RAGE).

    PubMed

    Mohan, Sepuru K; Gupta, Arun A; Yu, Chin

    2013-05-03

    S100A6 is involved in several vital biological functions, such as calcium sensing and cell proliferation. It is a homodimeric protein that belongs to the S100 protein family. The receptor for advanced glycation end products (RAGE) has been shown to play a role in the progression of various disease conditions, such as diabetes and immune/inflammatory disorders. Information regarding the association of RAGE with S100 proteins at a molecular level is useful to understand the diversity of the RAGE signaling pathways. In this report, biomolecular NMR techniques were utilized for the resonance assignment of the C3S mutation in human S100A6 and characterizing its interaction with the RAGE V domain. Further binding affinity between S100A6m and the RAGE V domain was determined by isothermal titration calorimetric studies. HADDOCK was used to generate a heterotetramer model of the S100A6m-RAGE V domain complex. This model provides an important insights into the S100-RAGE cellular signaling pathway.

  7. Immunohistochemical and ultrastructural detection of advanced glycation end products in atherosclerotic lesions of human aorta with a novel specific monoclonal antibody.

    PubMed Central

    Kume, S.; Takeya, M.; Mori, T.; Araki, N.; Suzuki, H.; Horiuchi, S.; Kodama, T.; Miyauchi, Y.; Takahashi, K.

    1995-01-01

    To elucidate the deposition of advanced glycation end products (AGEs) in aortic atherosclerosis, aortic walls were obtained from 25 autopsy cases and examined immunohistochemically and immunoelectron microscopically with a monoclonal antibody specific for AGEs, 6D12. Among the autopsy cases, atherosclerotic lesions were found in the aortas of 22 cases and were composed of diffuse intimal thickening, fatty streaks, atherosclerotic plaques, and/or complicated lesions. In these cases, intracellular AGE accumulation was demonstrated in the intimal lesions of aortic atherosclerosis in 12 cases. Compared with the diffuse intimal thickening, intracellular AGE accumulation was marked in the fatty streaks and atherosclerotic plaques. Immunohistochemical double staining with 6D12 and monoclonal antibodies for macrophages or muscle actin or a polyclonal antibody for scavenger receptors demonstrated that the AGE accumulation in macrophages or their related foam cells was marked in the diffuse intimal thickening and fatty streak lesions and that almost all macrophages and macrophage-derived foam cells possessed scavenger receptors. Immunoelectron microscopic observation revealed the localization of 6D12-positive reaction in lysosomal lipid vacuoles or electron-dense granules of the foam cells. These results indicate that AGE accumulation occurs in macrophages, smooth muscle cells, and their related foam cells. Images Figure 2 Figure 3 Figure 6 PMID:7545874

  8. Eplerenone restores 24-h blood pressure circadian rhythm and reduces advanced glycation end-products in rhesus macaques with spontaneous hypertensive metabolic syndrome

    PubMed Central

    Zhang, Yan; Zheng, Wen; Liu, Yuli; Wang, Jue; Peng, Ying; Shang, Haibao; Hou, Ning; Hu, Xiaomin; Ding, Yi; Xiao, Yao; Wang, Can; Zeng, Fanxin; Mao, Jiaming; Zhang, Jun; Ma, Dongwei; Sun, Xueting; Li, Chuanyun; Xiao, Rui-Ping; Zhang, Xiuqin

    2016-01-01

    Hypertension is often associated with metabolic syndrome (MetS), and serves as a risk factor of MetS and its complications. Blood pressure circadian rhythm in hypertensive patients has been suggested to contribute to cardiovascular consequences and organ damage of hypertension. But circadian changes of BP and their response to drugs have not been clearly investigated in non-human primates (NHPs) of MetS with hypertension. Here, we identified 16 elderly, hypertensive MetS rhesus monkeys from our in-house cohort. With implanted telemetry, we investigate BP changes and its circadian rhythm, together with the effect of antihypertensive drugs on BP and its diurnal fluctuation. MetS hypertensive monkeys displayed higher BP, obesity, glucose intolerance, and dyslipidemia. We also confirmed impaired 24-h BP circadian rhythm in MetS hypertensive monkeys. Importantly, Eplerenone, a mineralocorticoid receptor blocker, exerts multiple beneficial effects in MetS hypertensive monkeys, including BP reduction, 24-h BP circadian rhythm restoration, and decreased plasma concentration of inflammation factors and advanced glycation end-products. In summary, we identified a naturally-developed hypertensive MetS NHP model, which is of great value in the studies on pathogenesis of MetS-associated hypertension and development of novel therapeutic strategies. We also provided multiple novel mechanistic insights of the beneficial effect of Eplerenone on MetS with hypertension. PMID:27032687

  9. Inhibitory Potential of Constituents from Osmanthus fragrans and Structural Analogues Against Advanced Glycation End Products, α-Amylase, α-Glucosidase, and Oxidative Stress

    PubMed Central

    Yang, Ji-Yeon; Park, Jun-Hwan; Chung, Namhyun; Lee, Hoi-Seon

    2017-01-01

    Inhibition of α-amylase and α-glucosidase, advanced glycation end products (AGEs) formation, and oxidative stress by isolated active constituents of Osmanthus fragrans flowers (9,12-octadecadienoic acid and 4-(2,6,6-trimethyl-1-cyclohexenyl)-3-buten-2-one) and their structural analogues were evaluated. 9,12-Octadecadienoic acid was 10.02 and 22.21 times more active against α-amylase and α-glucosidase, respectively, than acarbose and ascorbic acid, followed by 9,12,15-octadecatrienoic acid, 9-octadecenoic acid, 4-(2,6,6-trimethyl-1-cyclohexenyl)-3-buten-2-one, 4-(2,6,6-trimethyl-2-cyclohexenyl)-3-buten-2-one, 1-heptadecanecarboxylic acid, and 1-pentadecanecarboxylic acid. Concerning the inhibition of AGEs formation, similar with data for 2,2’-diphenyl-1-picrylhydrazl radical scavenging activities, 9,12-octadecadienoic acid was 3.54 times more active than aminoguanidine, followed by 9,12,15-octadecatrienoic acid, and 9-octadecenoic acid. These results indicate that 4-(2,6,6-trimethyl-1-cyclohexenyl)-3-buten-2-one, 9,12-octadecadienoic acid and their analogues inhibit α-amylase and α-glucosidase, AGEs formation, and oxidative stress have potential value in alleviating diabetic pathological conditions. PMID:28361983

  10. Association of high mobility group BOX-1 and receptor for advanced glycation endproducts with clinicopathological features of haematological malignancies: a systematic review

    PubMed Central

    Bhavsar, Sheila B.; Riley, Erinn M.; Caponetti, Gabriel C.; Agrawal, Devendra K.

    2017-01-01

    High-mobility group box 1 (HMGB1) is a versatile protein with nuclear and extracellular functions. In the extracellular milieu, HMGB1 binds to several receptors, notably the receptor for advanced glycation end-products (RAGE). The expressions of HMGB1 and RAGE have been described in a variety of cancers. However, the clinical values of HMGB1 and RAGE in haematological malignancies have yet to be evaluated. A systematic search through PubMed and the Web of Science for articles discussing the role of HMGB1 and RAGE in haematological malignancies produced 15 articles. Overexpression of HMGB1 was reported to be associated with malignancy and, in certain studies, poor prognosis and tumour aggressiveness. Only one included study investigated the clinical value of RAGE, in which no significant difference was found between expression of RAGE in CLL neoplastic cells and nonmalignant controls. The discussed associations of HMGB1 and RAGE with clinicopathological characteristics of patients with haematological malignancies warrants further investigation into the prognostic and diagnostic value of both of these molecules. PMID:28239277

  11. Eplerenone restores 24-h blood pressure circadian rhythm and reduces advanced glycation end-products in rhesus macaques with spontaneous hypertensive metabolic syndrome.

    PubMed

    Zhang, Yan; Zheng, Wen; Liu, Yuli; Wang, Jue; Peng, Ying; Shang, Haibao; Hou, Ning; Hu, Xiaomin; Ding, Yi; Xiao, Yao; Wang, Can; Zeng, Fanxin; Mao, Jiaming; Zhang, Jun; Ma, Dongwei; Sun, Xueting; Li, Chuanyun; Xiao, Rui-Ping; Zhang, Xiuqin

    2016-04-01

    Hypertension is often associated with metabolic syndrome (MetS), and serves as a risk factor of MetS and its complications. Blood pressure circadian rhythm in hypertensive patients has been suggested to contribute to cardiovascular consequences and organ damage of hypertension. But circadian changes of BP and their response to drugs have not been clearly investigated in non-human primates (NHPs) of MetS with hypertension. Here, we identified 16 elderly, hypertensive MetS rhesus monkeys from our in-house cohort. With implanted telemetry, we investigate BP changes and its circadian rhythm, together with the effect of antihypertensive drugs on BP and its diurnal fluctuation. MetS hypertensive monkeys displayed higher BP, obesity, glucose intolerance, and dyslipidemia. We also confirmed impaired 24-h BP circadian rhythm in MetS hypertensive monkeys. Importantly, Eplerenone, a mineralocorticoid receptor blocker, exerts multiple beneficial effects in MetS hypertensive monkeys, including BP reduction, 24-h BP circadian rhythm restoration, and decreased plasma concentration of inflammation factors and advanced glycation end-products. In summary, we identified a naturally-developed hypertensive MetS NHP model, which is of great value in the studies on pathogenesis of MetS-associated hypertension and development of novel therapeutic strategies. We also provided multiple novel mechanistic insights of the beneficial effect of Eplerenone on MetS with hypertension.

  12. Inhibitory effect of the Cree traditional medicine wiishichimanaanh (Vaccinium vitis-idaea) on advanced glycation endproduct formation: identification of active principles.

    PubMed

    Beaulieu, Louis-Philippe; Harris, Cory S; Saleem, Ammar; Cuerrier, Alain; Haddad, Pierre S; Martineau, Louis C; Bennett, Steffany A L; Arnason, John T

    2010-05-01

    Like many aboriginal populations, First Nations communities such as the Cree of Eeyou Istchee are facing continuously increasing rates of diabetes and related complications. Advanced glycation endproducts (AGEs), which readily form and accumulate with sustained hyperglycemia, contribute to the development of diabetic complications and, as such, are considered a potential therapeutic target. In the present study, the inhibition of AGE formation by ethanolic extracts of the Cree medicinal plant Vaccinium vitis-idaea L. was assessed by fluorometric detection of fluorescent AGEs and immunodetection of N(epsilon)-(carboxymethyl)lysine adducts of albumin. Extracts from V. vitis-idaea berries demonstrated a concentration-dependent inhibition of AGE formation in both measures. High performance liquid chromatography mass spectrometry (HPLC/MS) identified nine main phenolic constituents. Four were selected for further testing, of which catechin, quercetin-3-O-galactoside and cyanidin-3-O-glucoside but not para-coumaric acid displayed antiglycation activities. These results demonstrate that the flavonoid components of the berry extract are potent antiglycation agents and provide pharmacological validation for the traditional use of V. vitis-idaea as an antidiabetic remedy.

  13. Characterization and cytological effects of a novel glycated gelatine substrate.

    PubMed

    Boonkaew, Benjawan; Tompkins, Kevin; Manokawinchoke, Jeeranan; Pavasant, Prasit; Supaphol, Pitt

    2014-04-01

    Hyperglycemia in diabetes results in the glycation of long-lived proteins. Protein glycation leads to the formation of advanced glycation end products (AGEs), which are implicated in delayed wound healing and other diabetes-associated pathologies, one of which is periodontal disease. Research into the mechanisms by which glycated long-lived proteins such as collagen exert their effects can allow for the understanding of diabetic pathologies and the development of appropriate treatments. However, the high cost of purified protein can be a limitation for many laboratories around the world. The objective of this study was to develop a low-cost in vitro model of glycated gelatine as an alternative to the glycated collagen model. We investigated the glycation of gelatine type A, a denatured form of collagen, which is low-cost and abundantly available. In this study, gelatine was incubated for 7 days with ribose or methylglyoxal (MG). Cross-linking, autofluorescence and UV-Vis spectrophotometry assays were performed and indicated a dose-dependent linear increase in cross-linking and autofluorescence of gelatine by ribose and MG. MG produced more cross-linking compared to ribose at the same concentrations. The UV-Vis spectra of the glycated gelatines confirmed the presence of AGE fluorophores. Because diabetes is a risk factor for periodontal disease, the effect of the glycated substrates on the basic behaviour of human periodontal ligament (HPDL) cells was evaluated. Glycation dose dependently reduced HPDL attachment and cell spreading, indicating that the novel glycated gelatine substrate affects cell behaviour. These results show that gelatine glycated with ribose or MG can be used as low-cost in vitro models to study the effects of protein glycation on cell behaviour in diabetes and ageing.

  14. Renoprotective and lipid-lowering effects of LR compounds, novel advanced glycation end product inhibitors, in streptozotocin-induced diabetic rats.

    PubMed

    Figarola, James Lester; Scott, Steven; Loera, Sofia; Xi, Bixin; Synold, Timothy; Rahbar, Samuel

    2005-06-01

    The accelerated formation of advanced glycation/lipoxidation end products (AGEs/ALEs) has been implicated in the pathogenesis of various diabetic complications. Several natural and synthetic compounds have been proposed and advanced as inhibitors of AGE/ALE formation. We examined the effects of two new AGE/ALE inhibitors, LR-9 and LR-74, on the prevention of early renal disease and dyslipidemia in streptozotocin (STZ)-induced diabetic rats. Diabetic rats were treated with either LR-9 or LR-74 for 32 weeks. Progression of renal disease was evaluated by measurements of urinary albumin and plasma creatinine concentrations. AGE-induced chemical modification of the tail tendon collagen and levels of Nepsilon-(carboxymethyl)- and (carboxyethyl)- lysines (CML and CEL) in skin collagen were measured. AGE/ALE levels in kidneys were determined by immunohistochemistry. Plasma lipids and their lipid hydroperoxide concentrations were also determined. Treatment of either LR-9 or LR-74 significantly inhibited the increase in albuminuria, plasma creatinine, hyperlipidemia, and plasma lipid peroxidation in diabetic rats without any effects on hyperglycemia. Both compounds also reduced CML-AGE accumulation in kidney glomeruli and tubules, AGE-linked fluorescence and cross-linking of tail collagen, and levels of CML and CEL in skin collagen. These results suggest that both LR compounds can inhibit the progression of renal disease and also prevent dyslipidemia in experimental diabetes. These compounds may have an additional beneficial effect as an antioxidant against lipid peroxidation, and thus may provide alternative therapeutic options for the treatment of various diabetic macrovascular complications.

  15. Serum soluble receptor for advanced glycation end products (sRAGE) is independently associated with cigarette smoking in non-diabetic healthy subjects.

    PubMed

    Biswas, Subrata K; Mudi, Sonchita R; Mollah, Forhadul H; Bierhaus, Angelika; Arslan, M Iqbal

    2013-07-01

    This study was designed to explore the relationship between serum levels of soluble receptor for advanced glycation end products (sRAGE) and cigarette smoking in non-diabetic healthy subjects. A total of 98 non-diabetic, otherwise healthy male subjects were recruited. A fasting blood sample and medical history including detail history of cigarette smoking was collected. The serum sRAGE levels were found significantly higher (p=0.002) in cigarette smokers (1475±422 pg/ml, n=45) compared with non-smokers (1165±350 pg/ml, n=53). Moreover, among the cigarette smokers, serum sRAGE levels were found significantly correlated with number of cigarettes smoked per day (r=0.60, p<0.001). In bivariate analysis in the total population, sRAGE positively correlated with smoking habit (r=0.37, p=0.002) and negatively correlated with systolic (r=-0.32, p=0.01) and diastolic blood pressure (r=-0.36, p=0.003). However, in stepwise multivariate linear regression model, sRAGE showed a significant independent association with smoking habit (b=0.32, p=0.007, R2=0.23). In conclusion, this study for the first time shows a significant elevation of serum sRAGE in cigarette smokers compared with non-smokers, a strong correlation between sRAGE and number of cigarettes smoked per day and an independent association of sRAGE with smoking habit in non-diabetic healthy subjects.

  16. Skin advanced glycation end products glucosepane and methylglyoxal hydroimidazolone are independently associated with long-term microvascular complication progression of type 1 diabetes.

    PubMed

    Genuth, Saul; Sun, Wanjie; Cleary, Patricia; Gao, Xiaoyu; Sell, David R; Lachin, John; Monnier, Vincent M

    2015-01-01

    Six skin collagen advanced glycation end products (AGEs) originally measured near to the time of the Diabetes Control and Complications Trial (DCCT) closeout in 1993 may contribute to the "metabolic memory" phenomenon reported in the follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study. We have now investigated whether the addition of four originally unavailable AGEs (i.e., glucosepane [GSPNE], hydroimidazolones of methylglyoxal [MG-H1] and glyoxal, and carboxyethyl-lysine) improves associations with incident retinopathy, nephropathy, and neuropathy events during 13-17 years after DCCT. The complete 10-AGE panel is associated with three-step Early Treatment of Diabetic Retinopathy Study scale worsening of retinopathy (P ≤ 0.002), independent of either mean DCCT or EDIC study A1C level. GSPNE and fructose-lysine (furosine [FUR]) correlate with retinopathy progression, independently of A1C level. The complete panel also correlates with microalbuminuria (P = 0.008) and FUR with nephropathy independently of A1C level (P ≤ 0.02). Neuropathy correlates with the complete panel despite adjustment for A1C level (P ≤ 0.005). MG-H1 and FUR are dominant, independent of A1C level (P < 0.0001), whereas A1C loses significance after adjustment for the AGEs. Overall, the added set of four AGEs enhances the association of the original panel with progression risk of retinopathy and neuropathy (P < 0.04) but not nephropathy, while GSPNE and MG-H1 emerge as the principal new risk factors. Skin AGEs are robust long-term markers of microvascular disease progression, emphasizing the importance of early and sustained implementation of intensive therapy.

  17. Increased serum levels of the specific advanced glycation end product methylglyoxal-derived hydroimidazolone are associated with retinopathy in patients with type 2 diabetes mellitus.

    PubMed

    Fosmark, Dag Sigurd; Torjesen, Peter A; Kilhovd, Bente K; Berg, Tore J; Sandvik, Leiv; Hanssen, Kristian F; Agardh, Carl-David; Agardh, Elisabet

    2006-02-01

    Advanced glycation end products (AGEs) are thought to play a major pathogenic role in diabetic retinopathy. The most important AGE is unknown, but as increased serum methylglyoxal-derived hydroimidazolone has been demonstrated in patients with type 2 diabetes mellitus, the aim of the present study was to elucidate possible associations between serum levels of hydroimidazolone and retinopathy in patients with type 2 diabetes mellitus. We recruited 227 patients with type 2 diabetes mellitus and retinopathy ranging from none to proliferative. Level of retinopathy was determined from 7 standard field stereo photographs per eye according to the Early Treatment Diabetic Retinopathy Study. The patients were 66 +/- 11 years old, with a known diabetes duration of 14 +/- 9 years. Serum levels of hydroimidazolone were determined with a competitive immunoassay. Serum levels of hydroimidazolone were increased in nonproliferative (median, 4.50 U/mL; interquartile range, 3.69-5.77 U/mL) and proliferative retinopathy (median, 4.88 U/mL; interquartile range, 3.70-6.52 U/mL) compared with patients without retinopathy (median, 4.02 U/mL; interquartile range, 3.47-4.88 U/mL) (P = .008 and .002, respectively). There was no association between hydroimidazolone and hemoglobin A1c (r = 0.04, P = .57). In addition, patients with proliferative retinopathy and a relatively short known duration of diabetes, that is, less than the median of 14 years, had increased serum levels of hydroimidazolone (median, 6.91 U/mL; interquartile range, 4.70-8.91 U/mL) compared with those with nonproliferative retinopathy (median, 4.34; interquartile range, 3.86-5.53U/mL, P = .015). Serum levels of hydroimidazolone are increased in type 2 diabetic patients with retinopathy. This association is independent of hitherto known associated factors, such as hemoglobin A1c.

  18. Inhibitory Activities of Stauntonia hexaphylla Leaf Constituents on Rat Lens Aldose Reductase and Formation of Advanced Glycation End Products and Antioxidant

    PubMed Central

    Hwang, Seung Hwan; Kwon, Shin Hwa; Kim, Set Byeol

    2017-01-01

    Stauntonia hexaphylla (Thunb.) Decne. (Lardizabalaceae) leaves (SHL) have been used traditionally as analgesics, sedatives, diuretics, and so on, in China. To date, no data have been reported on the inhibitory effect of SHL and its constituents on rat lens aldose reductase (RLAR) and advanced glycation end products (AGEs). Therefore, the inhibitory effect of compounds isolated from SHL extract on RLAR and AGEs was investigated to evaluate potential treatments of diabetic complications. The ethyl acetate (EtOAC) fraction of SHL extract showed strong inhibitory activity on RLAR and AGEs; therefore, EtOAc fraction (3.0 g) was subjected to Sephadex LH-20 column chromatography, for further fractionation, with 100% MeOH solvent system to investigate its effect on RLAR and AGEs. Phytochemical investigation of SHL led to the isolation of seven compounds. Among the isolated compounds, chlorogenic acid, calceolarioside B, luteolin-3′-O-β-D-glucopyranoside, quercetin-3-O-β-D-glucopyranoside, and luteolin-7-O-β-D-glucopyranoside exhibited significant inhibitory activity against RLAR with IC50 in the range of 7.34–23.99 μM. In addition, 3-(3,4-dihydroxyphenyl) propionic acid, neochlorogenic acid, and luteolin-3′-O-β-D-glucopyranoside exhibited the most potent inhibitory activity against formation of AGEs, with an IC50 value of 115.07–184.06 μM, compared to the positive control aminoguanidine (820.44 μM). Based on these findings, SHL dietary supplements could be considered for the prevention and/or treatment of diabetes complication. PMID:28326319

  19. Molecular characteristics of methylglyoxal-modified bovine and human serum albumins. Comparison with glucose-derived advanced glycation endproduct-modified serum albumins.

    PubMed

    Westwood, M E; Thornalley, P J

    1995-07-01

    The amino acid modification, gel filtration chromatographic, and electrophoretic characteristics of bovine and human serum albumins irreversibly modified by methylglyoxal (MG-SA) and by glucose-derived advanced glycation endproducts (AGE-SA) were investigated. Methylglyoxal selectively modified arginine residues at low concentration (1 mM); at high methylglyoxal concentration (100 mM), the extent of arginine modification increased and lysine residues were also modified. Both arginine and lysine residues were modified in AGE-SA. Analytical gel filtration HPLC of serum albumin derivatives suggested that the proportion of dimers and oligomers increased with modification in both low and highly modified MG-SA and AGE-SA derivatives relative to unmodified serum albumins. In SDS-PAGE analysis, dimers and oligomers of low-modified MG-SA were dissociated into monomers, but not in highly modified MG-SA. MG-SA had increased anodic electrophoretic mobility under nondenaturing conditions at pH 8.6, indicating an increased net negative charge, which increased with extent of modification; highly modified MG-SA and AGE-SA had similar high electrophoretic mobilities. MG-SA derivatives were fluorescent: the fluorescence was characteristic of the arginine-derived imidazolone N delta-(5-methyl-4-imidazolon-2-yl)ornithine, but other fluorophores were also present. AGE-SA had similar fluorescence, attributed, in part, to glucose-derived imidazolones. AGE formed from glucose-modified proteins and AGE-like compounds formed from methylglyoxal-modified proteins may both be signals for recognition and degradation of senescent macromolecules.

  20. Dietary intake of advanced glycation end products did not affect endothelial function and inflammation in healthy adults in a randomized controlled trial.

    PubMed

    Semba, Richard D; Gebauer, Sarah K; Baer, David J; Sun, Kai; Turner, Randi; Silber, Harry A; Talegawkar, Sameera; Ferrucci, Luigi; Novotny, Janet A

    2014-07-01

    When food is heated to high temperatures, the characteristic "browning" generates advanced glycation end products (AGEs). AGEs are associated with an increased risk of cardiovascular disease, diabetes, and other adverse outcomes. Whether dietary AGEs are absorbed and are harmful to human health remains highly controversial. The objective of this study was to compare the effects of a diet high or low in AGEs on endothelial function, circulating AGEs, inflammatory mediators, and circulating receptors for AGEs in healthy adults. A randomized, parallel-arm, controlled dietary intervention was conducted for 6 wk with 24 healthy adults, aged 50-69 y, that compared isocaloric, food-equivalent diets that were prepared at either high or mild temperatures. Peripheral arterial tonometry, serum and urine carboxymethyl-lysine (CML), inflammatory mediators (interleukin-6, C-reactive protein, vascular adhesion molecule-1, and tumor necrosis factor-α receptors I and II), soluble receptor for AGEs, and endogenous secretory receptor for AGEs were measured at baseline and after 6 wk of dietary intervention. In the low-AGE diet group, the following changed from baseline to 6 wk (mean ± SE): serum CML from 763 ± 24 to 679 ± 29 ng/mL (P = 0.03) and urine CML from 1.37 ± 1.47 to 0.77 ± 2.01 μg/mL creatinine (P = 0.02). There were no significant changes in serum and urinary CML concentrations from baseline to follow-up in the high-AGE diet group. A high- or low-AGE diet had no significant impact on peripheral arterial tonometry or any inflammatory mediators after 6 wk of dietary intervention. In healthy middle-aged to older adults, consumption of a diet high or low in AGEs for 6 wk had no impact on endothelial function and inflammatory mediators, 2 precursors of cardiovascular disease.

  1. Advanced glycation end-products induce skeletal muscle atrophy and dysfunction in diabetic mice via a RAGE-mediated, AMPK-down-regulated, Akt pathway.

    PubMed

    Chiu, Chen-Yuan; Yang, Rong-Sen; Sheu, Meei-Ling; Chan, Ding-Cheng; Yang, Ting-Hua; Tsai, Keh-Sung; Chiang, Chih-Kang; Liu, Shing-Hwa

    2016-02-01

    Diabetic myopathy, a less studied complication of diabetes, exhibits the clinical observations characterized by a less muscle mass, muscle weakness and a reduced physical functional capacity. Accumulation of advanced glycation end-products (AGEs), known to play a role in diabetic complications, has been identified in ageing human skeletal muscles. However, the role of AGEs in diabetic myopathy remains unclear. Here, we investigated the effects of AGEs on myogenic differentiation and muscle atrophy in vivo and in vitro. We also evaluated the therapeutic potential of alagebrium chloride (Ala-Cl), an inhibitor of AGEs. Muscle fibre atrophy and immunoreactivity for AGEs, Atrogin-1 (a muscle atrophy marker) and phosphorylated AMP-activated protein kinase (AMPK) expressions were markedly increased in human skeletal muscles from patients with diabetes as compared with control subjects. Moreover, in diabetic mice we found increased blood AGEs, less muscle mass, lower muscular endurance, atrophic muscle size and poor regenerative capacity, and increased levels of muscle AGE and receptor for AGE (RAGE), Atrogin-1 and phosphorylated AMPK, which could be significantly ameliorated by Ala-Cl. Furthermore, in vitro, AGEs (in a dose-dependent manner) reduced myotube diameters (myotube atrophy) and induced Atrogin-1 protein expression in myotubes differentiated from both mouse myoblasts and primary human skeletal muscle-derived progenitor cells. AGEs exerted a negative regulation of myogenesis of mouse and human myoblasts. Ala-Cl significantly inhibited the effects of AGEs on myotube atrophy and myogenesis. We further demonstrated that AGEs induced muscle atrophy/myogenesis impairment via a RAGE-mediated AMPK-down-regulation of the Akt signalling pathway. Our findings support that AGEs play an important role in diabetic myopathy, and that an inhibitor of AGEs may offer a therapeutic strategy for managing the dysfunction of muscle due to diabetes or ageing.

  2. Polymorphisms of the promoter and exon 3 of the receptor for advanced glycation end products (RAGE) in Euro- and Afro-Brazilians.

    PubMed

    Torres, M C; Beltrame, M H; Santos, I C R; Picheth, G; Petzl-Erler, M L; Pedrosa, F O; Steffens, M B R; de Souza, E M

    2012-04-01

    The receptor for advanced glycation end products (RAGE or AGER), a member of the immunoglobulin superfamily, is involved in pathologies such as atherosclerosis and diabetes. Over 50 SNPs were reported for RAGE, among which were the promoter region polymorphisms -429T>C (rs1800625), -374T>A (rs1800624) and a 63-bp deletion (-407 to -345 bp), all related to increased RAGE expression. Additionally, in the exon 3, a putative site of binding ligands, the missense variation G82S (rs2070600) was associated with skin disorders in patients with diabetes. We have determined allele, genotype and haplotype frequencies of RAGE polymorphisms -429T>C, -374T>A, 63-bp deletion and G82S in Euro-Brazilians (n = 108) and Afro-Brazilians (n = 91), characterized according to the predominant ancestry of the individuals. The allele frequencies for Euro- and Afro-Brazilians were as follows: -429C, 12.5% vs. 12.1% (P = 0.90); -374A, 31.5% vs. 26.2% (P = 0.25); 63del, 0.0% vs. 3.8% (P = 0.004); and 82S, 1.9% vs. 0.6% (P = 0.24). Absolute linkage disequilibrium was found between the promoter polymorphisms -429T>C and -374T>A plus the 63-bp deletion (D'=1.000; P < 0.0001). The haplotype frequencies differed (P = 0.003) between Euro- and Afro-Brazilians. Our results showed that the frequencies of the 63-bp deletion were higher in Afro-Brazilians, while the other analysed polymorphisms were similarly distributed in the studied populations. The -374T>A plus 63-bp deletion polymorphism captures more than 80% of the haplotypic variation in the studied population.

  3. Advanced glycation end products induce in vitro cross-linking of alpha-synuclein and accelerate the process of intracellular inclusion body formation.

    PubMed

    Shaikh, Shamim; Nicholson, Louise F B

    2008-07-01

    Cross-linking of alpha-synuclein and Lewy body formation have been implicated in the dopaminergic neuronal cell death observed in Parkinson's disease (PD); the mechanisms responsible, however, are not clear. Reactive oxygen species and advanced glycation end products (AGEs) have been found in the intracellular, alpha-synuclein-positive Lewy bodies in the brains of both PD as well as incidental Lewy body disease patients, suggesting a role for AGEs in alpha-synuclein cross-linking and Lewy body formation. The aims of the present study were to determine 1) whether AGEs can induce cross-linking of alpha-synuclein peptides, 2) the progressive and time-dependent intracellular accumulation of AGEs and inclusion body formation, and 3) the effects of extracellular or exogenous AGEs on intracellular inclusion formation. We first investigated the time-dependent cross-linking of recombinant human alpha-synuclein in the presence of AGEs in vitro, then used a cell culture model based on chronic rotenone treatment of human dopaminergic neuroblastoma cells (SH-SY5Y) over a period of 1-4 weeks, in the presence of different doses of AGEs. Cells (grown on coverslips) and cell lysates, collected at the end of every week, were analyzed for the presence of intracellular reactive oxygen species, AGEs, alpha-synuclein proteins, and intracellular alpha-synuclein- and AGE-positive inclusion bodies by using immunocytochemical, biochemical, and Western blot techniques. Our results show that AGEs promote in vitro cross-linking of alpha-synuclein, that intracellular accumulation of AGEs precedes alpha-synuclein-positive inclusion body formation, and that extracellular AGEs accelerate the process of intracellular alpha-synuclein-positive inclusion body formation.

  4. Serum Level of Endogenous Secretory Receptor for Advanced Glycation End Products and Other Factors in Type 2 Diabetic Patients With Mild Cognitive Impairment

    PubMed Central

    Chen, Gang; Cai, Liangchun; Chen, Bin; Liang, Jixing; Lin, Fenhui; Li, Liantao; Lin, Lixiang; Yao, Jin; Wen, Junping; Huang, Huibin

    2011-01-01

    OBJECTIVE Determine the serum levels of endogenous secretory receptor for advanced glycation end products (esRAGEs) in patients with type 2 diabetes and mild cognitive impairment (MCI) and in control patients with type 2 diabetes but no MCI, and examine the relationship of esRAGE and MCI with other clinical factors. RESEARCH DESIGN AND METHODS A total of 101 patients with type 2 diabetes who were hospitalized in the Department of Endocrinology at Fujian Provincial Hospital between January 2010 and January 2011 were enrolled. There were 58 patients with MCI and 43 patients without MCI (control). Serum levels of esRAGE were measured using an enzyme-linked immunosorbent assay (ELISA). Other clinical parameters were also measured. RESULTS Type 2 diabetic patients with MCI had a longer duration of diabetes; elevated HbA1c, total cholesterol (CHOL), LDL cholesterol (LDL-C), triglyceride (TG), intima-media thickness, C-reactive protein (CRP), and brachial-ankle pulse wave velocity (ba-PWV); and lower ankle brachial index (ABI) and esRAGE relative to the control group. Among patients with MCI, the Montreal Cognitive Assessment (MoCA) score was positively correlated with serum esRAGE but negatively correlated with CHOL. Spearman rank correlation analysis indicated that esRAGE was positively correlated with MoCA score and ABI but negatively correlated with ba-PWV, CHOL, TG, and CRP in all subjects. CONCLUSIONS Our results suggest that esRAGE may be a potential protective factor for dyslipidemia, atherosclerosis, and MCI in patients with type 2 diabetes. PMID:22011410

  5. Serum Level of Soluble Receptor for Advanced Glycation End Products Is Associated with A Disintegrin And Metalloproteinase 10 in Type 1 Diabetes

    PubMed Central

    Lee, Alan C. H.; Lam, Joanne K. Y.; Shiu, Sammy W. M.; Wong, Ying; Betteridge, D. John; Tan, Kathryn C. B.

    2015-01-01

    Background The receptor for advanced glycation end products (RAGE) is involved in the pathogenesis of diabetic complications, and soluble forms of the receptor (sRAGE) can counteract the detrimental action of the full-length receptor by acting as decoy. Soluble RAGE is produced by alternative splicing [endogenous secretory RAGE (esRAGE)] and/or by proteolytic cleavage of the membrane-bound receptor. We have investigated the role of A Disintegrin And Metalloproteinase 10 (ADAM10) in the ectodomain shedding of RAGE. Methods Constitutive and insulin-induced shedding of RAGE in THP-1 macrophages by ADAM10 was evaluated using an ADAM10-specific metalloproteinase inhibitor. Serum ADAM10 level was measured in type 1 diabetes and control subjects, and the association with serum soluble RAGE was determined. Serum total sRAGE and esRAGE were assayed by ELISA and the difference between total sRAGE and esRAGE gave an estimated measure of soluble RAGE formed by cleavage (cRAGE). Results RAGE shedding (constitutive and insulin-induced) was significantly reduced after inhibition of ADAM10 in macrophages, and insulin stimulated ADAM10 expression and activity. Diabetic subjects have higher serum total sRAGE and esRAGE (p<0.01) than controls, and serum ADAM10 was also increased (p<0.01). Serum ADAM10 correlated with serum cRAGE in type 1 diabetes (r = 0.40, p<0.01) and in controls (r = 0.31. p<0.01) but no correlations were seen with esRAGE. The association remained significant after adjusting for age, gender, BMI, smoking status and HbA1c. Conclusion Our data suggested that ADAM10 contributed to the shedding of RAGE. Serum ADAM10 level was increased in type 1 diabetes and was a significant determinant of circulating cRAGE. PMID:26325204

  6. Effects of Two Different Dietary Patterns on Inflammatory Markers, Advanced Glycation End Products and Lipids in Subjects without Type 2 Diabetes: A Randomised Crossover Study.

    PubMed

    Kim, Yoona; Keogh, Jennifer B; Clifton, Peter M

    2017-03-29

    Epidemiological studies suggest that consumption of red and processed meat and refined grains are associated with type 2 diabetes and metabolic syndrome and increased inflammatory and fibrinolytic markers. We hypothesised that a diet high in red and processed meat and refined grains (HMD) would increase inflammatory markers and advanced glycation end products (AGEs) compared with a diet high in dairy, whole grains, nuts and legumes (HWD). We performed a randomised crossover study of two four-week interventions in 51 participants without type 2 diabetes (15 men and 36 women aged 35.1 ± 15.6 years; body mass index: 27.7 ± 6.9 kg/m²). No baseline measurements were performed. Plasma fluorescent AGEs, carboxymethyllysine, glucose, insulin, lipids, hs-CRP, interleukin 6 (IL-6) and plasminogen activator inhibitor-1 (PAI-1) were analysed after four weeks on each diet. IL-6, hs-CRP, AGEs and carboxymethyllysine were not different between diets but PAI-1 was higher after the HMD than after HWD ((median and interquartile range) 158, 81 vs. 121, 53 ng/mL p < 0.001). PAI-1 on the HWD diet was inversely correlated with whole grains intake (p = 0.007). PAI-1 was inversely correlated with insulin sensitivity index (r = -0.45; p = 0.001) and positively correlated with serum total cholesterol (r = 0.35; p = 0.012) and serum triglyceride (r = 0.32; p = 0.021) on HMD. This trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12614000519651).

  7. Advanced glycation end products promote the proliferation and migration of primary rat vascular smooth muscle cells via the upregulation of BAG3.

    PubMed

    Li, Cunshu; Chang, Ye; Li, Yuan; Chen, Shuang; Chen, Yintao; Ye, Ning; Dai, Dongxue; Sun, Yingxian

    2017-03-28

    The present study was aimed to investigate the role of reactive oxygen species (ROS) on advanced glycation end product (AGE)-induced proliferation and migration of vascular smooth muscle cells (VSMCs) and whether Bcl-2‑associated athanogene 3 (BAG3) is involved in the process. Primary rat VSMCs were extracted and cultured in vitro. Cell viability was detected by MTT assay and cell proliferation was detected by EdU incorporation assay. Cell migration was detected by wound healing and Transwell assays. BAG3 was detected using qPCR and western blot analysis. Transcriptional and translational inhibitors (actinomycin D and cycloheximide, respectively) were used to study the effect of AGEs on the expression of BAG3 in VSMCs. Lentiviral plasmids containing short hairpin RNA (shRNA) against rat BAG3 or control shRNA were transduced into VSMCs. Cellular ROS were detected by 2',7'-dichlorofluorescein diacetate (DCFH-DA) staining. Mitochondrial membrane potential was detected by tetramethylrhodamine methyl ester (TMRE) staining. AGEs significantly increased the expression of BAG3 in a dose-and time-dependent manner. Furthermore, AGEs mainly increased the expression of BAG3 mRNA by increasing the RNA synthesis rather than inhibiting the RNA translation. BAG3 knockdown reduced the proliferation and migration of VSMCs induced by AGEs. BAG3 knockdown reduced the generation of ROS and sustained the mitochondrial membrane potential of VSMCs. Reduction of ROS production by N-acetylcysteine (NAC), a potent antioxidant, also reduced the proliferation and migration of VSMCs. On the whole, the present study demonstrated for the first time that AGEs could increase ROS production and promote the proliferation and migration of VSMCs by upregulating BAG3 expression. This study indicated that BAG3 should be considered as a potential target for the prevention and/or treatment of vascular complications of diabetes.

  8. Associations between Soluble Receptor for Advanced Glycation End Products (sRAGE) and S100A12 (EN-RAGE) with Mortality in Long-term Hemodialysis Patients

    PubMed Central

    2017-01-01

    Hemodialysis (HD) patients experience vascular calcification, ultimately leading to high mortality rates. Previously, we reported associations between soluble receptor for advanced glycation end products (sRAGEs) and extracellular newly identified RAGE-binding protein S100A12 (EN-RAGE) and vascular calcification. Here, we extended our observations, investigating whether these biomarkers may be useful for predicting cardiovascular morbidity and mortality in these subjects. Thus, we evaluated the relationship between sRAGE and S100A12 and mortality in long-term HD patients. This was a prospective observational cohort study in 199 HD patients from an extended analysis of our previous study. Plasma sRAGE, S100A12, comorbidities, and other traditional risk factors were investigated. The cumulative incidences for death using Cox proportional hazards regression were evaluated in multivariable analyses. The observation period was 44 months. During the observation period, 27 (13.6%) patients died. Univariate analysis demonstrated that S100A12 was correlated with diabetes (P = 0.040) and high-sensitivity C-reactive protein (hsCRP) (P = 0.006). In multivariable analyses, plasma sRAGE (hazard ratio [HR] = 1.155; 95% confidence interval [CI] = 0.612–2.183; P = 0.656) and S100A12 (HR = 0.960; 95% CI = 0.566–1.630; P = 0.881) were not associated with mortality in HD patients, although traditional predictors of mortality, including age, history of cardiovascular diseases (CVDs), and serum levels of albumin and hsCRP were related to mortality. Powerful predictors of mortality were age, CVD, and albumin levels. Plasma sRAGE and S100A12 may be weak surrogate markers for predicting all-cause mortality in patients undergoing HD, although S100A12 was partly related to diabetes and inflammation. PMID:27914132

  9. Putative model for heat shock protein 70 complexation with receptor of advanced glycation end products through fluorescence proximity assays and normal mode analyses.

    PubMed

    Grunwald, Marcelo Sartori; Ligabue-Braun, Rodrigo; Souza, Cristiane Santos; Heimfarth, Luana; Verli, Hugo; Gelain, Daniel Pens; Moreira, José Cláudio Fonseca

    2017-01-01

    Extracellular heat shock protein 70 (HSP70) is recognized by receptors on the plasma membrane, such as Toll-like receptor 4 (TLR4), TLR2, CD14, and CD40. This leads to activation of nuclear factor-kappa B (NF-κB), release of pro-inflammatory cytokines, enhancement of the phagocytic activity of innate immune cells, and stimulation of antigen-specific responses. However, the specific characteristics of HSP70 binding are still unknown, and all HSP70 receptors have not yet been described. Putative models for HSP70 complexation to the receptor for advanced glycation endproducts (RAGEs), considering both ADP- and ATP-bound states of HSP70, were obtained through molecular docking and interaction energy calculations. This interaction was detected and visualized by a proximity fluorescence-based assay in A549 cells and further analyzed by normal mode analyses of the docking complexes. The interacting energy of the complexes showed that the most favored docking situation occurs between HSP70 ATP-bound and RAGE in its monomeric state. The fluorescence proximity assay presented a higher number of detected spots in the HSP70 ATP treatment, corroborating with the computational result. Normal-mode analyses showed no conformational deformability in the interacting interface of the complexes. Results were compared with previous findings in which oxidized HSP70 was shown to be responsible for the differential modulation of macrophage activation, which could result from a signaling pathway triggered by RAGE binding. Our data provide important insights into the characteristics of HSP70 binding and receptor interactions, as well as putative models with conserved residues on the interface area, which could be useful for future site-directed mutagenesis studies.

  10. Advanced Glycation End-Products Induce Apoptosis in Pancreatic Islet Endothelial Cells via NF-κB-Activated Cyclooxygenase-2/Prostaglandin E2 Up-Regulation

    PubMed Central

    Lan, Kuo-Cheng; Chiu, Chen-Yuan; Kao, Chia-Wei; Huang, Kuo-How; Wang, Ching-Chia; Huang, Kuo-Tong; Tsai, Keh-Sung

    2015-01-01

    Microvascular complications eventually affect nearly all patients with diabetes. Advanced glycation end-products (AGEs) resulting from hyperglycemia are a complex and heterogeneous group of compounds that accumulate in the plasma and tissues in diabetic patients. They are responsible for both endothelial dysfunction and diabetic vasculopathy. The aim of this study was to investigate the cytotoxicity of AGEs on pancreatic islet microvascular endothelial cells. The mechanism underlying the apoptotic effect of AGEs in pancreatic islet endothelial cell line MS1 was explored. The results showed that AGEs significantly decreased MS1 cell viability and induced MS1 cell apoptosis in a dose-dependent manner. AGEs dose-dependently increased the expressions of cleaved caspase-3, and cleaved poly (ADP-ribose) polymerase in MS1 cells. Treatment of MS1 cells with AGEs also resulted in increased nuclear factor (NF)-κB-p65 phosphorylation and cyclooxygenase (COX)-2 expression. However, AGEs did not affect the expressions of endoplasmic reticulum (ER) stress-related molecules in MS1 cells. Pretreatment with NS398 (a COX-2 inhibitor) to inhibit prostaglandin E2 (PGE2) production reversed the induction of cleaved caspase-3, cleaved PARP, and MS1 cell viability. Moreover, AGEs significantly increased the receptor for AGEs (RAGE) protein expression in MS1 cells, which could be reversed by RAGE neutralizing antibody. RAGE Neutralizing antibody could also reverse the induction of cleaved caspase-3 and cleaved PARP and decreased cell viability induced by AGEs. These results implicate the involvement of NF-κB-activated COX-2/PGE2 up-regulation in AGEs/RAGE-induced islet endothelial cell apoptosis and cytotoxicity. These findings may provide insight into the pathological processes within the pancreatic islet microvasculature induced by AGEs accumulation. PMID:25898207

  11. Beneficial effects of banana (Musa sp. var. elakki bale) flower and pseudostem on hyperglycemia and advanced glycation end-products (AGEs) in streptozotocin-induced diabetic rats.

    PubMed

    Bhaskar, Jamuna J; Shobha, Mysore S; Sambaiah, Kari; Salimath, Paramahans V

    2011-09-01

    Diabetes is a chronic health problem and major cause of death in most of the countries. Diet management plays an important role in controlling diabetes and its complications along with insulin and drugs. We have examined the effect of banana (Musa sp. var. elakki bale) flower and pseudostem on hyperglycemia and advanced glycation end-products (AGEs) in streptozotocin-induced diabetic rats. Our results indicated that banana flower and pseudostem have low glycemic index and have a high content of dietary fiber and antioxidants. Diabetic symptoms like hyperglycemia, polyuria, polyphagia, polydipsia, urine sugar, and body weight were ameliorated in banana flower- and pseudostem-treated rats. Increased glomerular filtration rate in the diabetic group (5.1 ± 0.22 ml/min) was decreased in banana flower-fed (2.5 ± 0.37 ml/min) and pseudostem-fed (3.0 ± 0.45 ml/min) groups and were significant at P < 0.001 and P < 0.01, respectively. Fructosamine and AGEs formed during diabetes were inhibited in treated groups when compared with the diabetic group. The diabetic group showed 11.5 ± 0.64 μg of AGEs/mg protein in kidney, whereas, in banana flower- and pseudostem-fed groups, it was reduced to 9.21 ± 0.32 and 9.29 ± 0.24 μg/mg protein, respectively, and were significant at P < 0.01. These findings suggest that banana flower and pseudostem have anti-diabetic and anti-AGEs properties and are beneficial as food supplements for diabetics.

  12. Mesenchymal stem cells protects hyperoxia-induced lung injury in newborn rats via inhibiting receptor for advanced glycation end-products/nuclear factor κB signaling.

    PubMed

    Tian, Zhaofang; Li, Yuhong; Ji, Ping; Zhao, Sai; Cheng, Huaipin

    2013-02-01

    Bone marrow-derived mesenchymal stem cells (BMSCs) have been shown recently to ameliorate hyperoxia-induced lung injury, but the underlying mechanism remains unclear. This study aimed to determine whether BMSCs attenuate hyperoxia-induced lung injury by down-modulating the inflammatory RAGE/NF-κB (receptor for advanced glycation end-products/nuclear factor-κB) signaling. Thirty Sprague-Dawley newborn rats were randomly divided into three groups (n = 10): sham control (C); hyperoxia-induced acute lung injury (ALI) (B) and ALI with BMSCs transplantation (A). Rats were sacrificed at three-day post-transplantation. RAGE and NF-κB expression in lung tissue was detected by reverse transcription polymerase chain reaction, Western blot and immunohistochemistry analysis. The levels of tumor necrosis factor α (TNF-α) and RAGE in bronchoalveolar lavage fluid (BALF) and in serum were detected by enzyme-linked immunosorbent assay. The lung damage was evaluated by histological examination. The results showed that RAGE and TNF-α concentrations in BALF were significantly lower in Group A than in Group B. Moreover, RAGE and NF-κB expression in lung tissue at mRNA and protein concentrations was significantly lower in Group A than in Group B. The lung damage score was significantly lower in Group A than in Group B. These data demonstrate that hyperoxia induces the inflammation and causes damage in the lung but BMSC transplantation could alleviate hyperoxia-induced lung injury by inhibiting the inflammatory process mediated by RAGE/NF-κB signaling.

  13. Vitreous advanced glycation endproducts and α-dicarbonyls in retinal detachment patients with type 2 diabetes mellitus and non-diabetic controls

    PubMed Central

    Mulder, Douwe J.; Schalkwijk, Casper G.; Scheijen, Jean L.; Smit, Andries J.; Los, Leonoor I.

    2017-01-01

    Purpose Advanced glycation endproducts (AGEs) and their precursors α-dicarbonyls are implicated in the progression of diabetic retinopathy. The purpose of this study was to assess AGEs and α-dicarbonyls in the vitreous of patients with type 2 diabetes mellitus (T2DM) with early stages or absence of diabetic retinopathy. Methods We examined vitreous samples obtained during vitrectomy from 31 T2DM patients presenting themselves with rhegmatogenous retinal detachment and compared these to 62 non-diabetic rhegmatogenous retinal detachment patients, matched on age, estimated glomerular filtration rate, smoking, intra-ocular lens implantation, and proliferative vitreoretinopathy. AGEs (pentosidine, Nε-(carboxymethyl)lysine, Nε-(carboxyethyl)lysine, and 5-hydro-5-methylimidazolone) and α-dicarbonyls (3-deoxyglucosone, methylglyoxal, and glyoxal) were measured by ultra performance liquid chromatography or high performance liquid chromatography. Skin autofluorescence was measured by the AGE Reader. Results Mean age was 64 ± 7.6 years for T2DM patients and 63 ± 8.1 years for controls. For T2DM patients, median diabetes duration was 2.2 (0.3–7.4) years. Non-proliferative diabetic retinopathy was present in 1 patient and classified as absent or background retinopathy in 30 patients. Vitreous levels of pentosidine (2.20 vs. 1.59 μmol/mol lysine, p = 0.012) and 3-deoxyglucosone (809 vs. 615 nmol/L, p = 0.001) were significantly elevated in T2DM patients compared to controls. Other AGEs and α-dicarbonyls in the vitreous were not significantly different. There was a trend for increased skin autofluorescence in T2DM patients as compared to controls (p = 0.07). Conclusions Pentosidine and 3-deoxyglucosone concentrations were increased in the vitreous of rhegmatogenous retinal detachment patients with a relatively short duration of diabetes compared to non-diabetic rhegmatogenous retinal detachment patients. PMID:28264049

  14. Glucagon-like peptide-1 counteracts the detrimental effects of Advanced Glycation End-Products in the pancreatic beta cell line HIT-T 15

    SciTech Connect

    Puddu, A.; Storace, D.; Durante, A.; Odetti, P.; Viviani, G.L.

    2010-07-30

    Research highlights: {yields} GLP-1 prevents AGEs-induced cell death. {yields} GLP-1 prevents AGEs-induced oxidative stress. {yields} GLP-1 ameliorated AGEs-induced cell dysfunction. {yields} GLP-1 attenuates AGEs-induced RAGE increment. {yields} GLP-1 counteracts AGEs-induced pancreatic cell death and dysfunction. -- Abstract: Advanced Glycation End-Products (AGEs), a group of compounds resulting from the non-enzymatic reaction of reducing sugars with the free amino group of proteins, are implicated in diabetic complications. We previously demonstrated that exposure of the pancreatic islet cell line HIT-T 15 to high concentrations of AGEs significantly decreases cell proliferation and insulin secretion, and affects transcription factors regulating insulin gene transcription. The glucagon-like peptide-1 (GLP-1) is an incretin hormone that increases proinsulin biosynthesis, stimulates insulin secretion, and improves pancreatic beta-cell viability. The aim of this work was to investigate the effects of GLP-1 on the function and viability of HIT-T 15 cells cultured with AGEs. HIT-T 15 cells were cultured for 5 days in presence of AGEs alone, or supplemented with 10 nmol/l GLP-1. Cell viability, insulin secretion, redox balance, and expression of the AGEs receptor (RAGE) were then determined. The results showed that GLP-1 protected beta cell against AGEs-induced cell death preventing both apoptosis and necrosis. Moreover, addition of GLP-1 to the AGEs culture medium restored the redox balance, improved the responsiveness to glucose, and attenuated AGEs-induced RAGE expression. These findings provide evidence that GLP-1 protects beta cells from the dangerous effects of AGEs.

  15. Dietary consumption of meat, fat, animal products and advanced glycation end-products and the risk of barrett’s esophagus

    PubMed Central

    Jiao, Li; Kramer, Jennifer R.; Chen, Liang; Rugge, Massimo; Parente, Paola; Verstovsek, Gordana; Alsarraj, Abeer; El-Serag, Hashem B.

    2013-01-01

    Background Advanced glycation end-products (AGEs) are found in high quantity in high-fat foods and meat cooked at high temperature. AGEs have been shown to contribute to chronic inflammation and oxidative stress in humans. Aim To investigate the associations between consumption of meat, fat and AGEs, and risk of Barrett’s esophagus (BE). Methods We conducted a case-control study using data from the patients who were scheduled for elective esophagogastroduodenoscopy (EGD) and from a random sample of patients who were identified at primary care clinics. Daily consumption of meat, fat and Nε-(carboxymethyl) lysine (CML), a major type of AGEs, was derived from the food frequency questionnaire (FFQ). Multivariate logistic regression models were used to estimate the odds ratio (OR) and its 95% confidence interval (CI) for BE. Results A total of 151 cases with BE and 777 controls without BE completed the FFQ. The multivariate OR (95% CI) for BE was 1.91 (1.07–3.38) for total meat, 1.80 (1.02–3.16) for saturated fat, and 1.63 (0.96–2.76) for CML-AGE, when the highest tertile of intake was compared with the lowest. The association for total meat was attenuated to 1.61 (0.82–3.16), and that for saturated fat to 1.54 (0.81–2.94) after adjusting for CML-AGE. Conclusions Higher consumption of total meat, saturated fat or possibly CML-AGE was associated with an increased risk of BE. CML-AGE may partly explain the association between total meat and saturated fat consumption and risk of BE. PMID:23957669

  16. Association of Advanced Glycation End Products with coronary Artery Calcification in Japanese Subjects with Type 2 Diabetes as Assessed by Skin Autofluorescence

    PubMed Central

    Hangai, Mari; Takebe, Noriko; Honma, Hiroyuki; Sasaki, Atsumi; Chida, Ai; Nakano, Rieko; Togashi, Hirobumi; Nakagawa, Riyuki; Oda, Tomoyasu; Matsui, Mizue; Yashiro, Satoshi; Nagasawa, Kan; Kajiwara, Takashi; Takahashi, Kazuma; Takahashi, Yoshihiko; Satoh, Jo

    2016-01-01

    Aim: Advanced glycation end products (AGE) are considered to be among the critical pathogenic factors involved in the progression of diabetic complications. Skin autofluorescence (AF), a noninvasive measurement of AGE accumulation, has been recognized as a useful and convenient marker for diabetic vascular diseases in Caucasians. This study aimed to evaluate the association of tissue AGE, assessed using skin AF, with coronary artery calcification in Japanese subjects with type 2 diabetes. Methods: In total, 122 Japanese subjects with type 2 diabetes enrolled in this cross-sectional study underwent multi-slice computed tomography for total coronary artery calcium scores (CACS) estimation and examination with a skin AF reader. Results: Skin AF positively correlated with age, sex, diabetes duration, pulse wave velocity, systolic blood pressure, serum creatinine, and CACS. In addition, skin AF results negatively correlated with BMI, eGFR, and serum C-peptide concentration. According to multivariate analysis, age and systolic blood pressure showed strong positive correlation and eGFR showed negative correlation with skin AF values. Multiple linear regression analyses revealed a significant positive correlation between skin AF values and logCACS, independent of age, sex, diabetes duration, HbA1c, BMI, IMT, and blood pressure. However, skin AF showed no association with serum levels of AGE, such as Nε-(carboxymethyl) lysine and 3-deoxyglucosone. Conclusion: Skin AF results positively correlated with CACS in Japanese subjects with type 2 diabetes. This result indicates that AGE plays a role in the pathogenesis of diabetic macrovascular disease. Measurement of skin AF values may be useful for assessing the severity of diabetic complications in Japanese subjects. PMID:26961217

  17. Determinants of concentrations of Nε-carboxymethyl-lysine and soluble receptor for advanced glycation end products and their associations with risk of pancreatic cancer

    PubMed Central

    Duan, Zhigang; Chen, Guoqing; Chen, Liang; Stolzenberg-Solomon, Rachael; Weinstein, Stephanie J; Mannisto, Satu; White, Donna L; Albanes, Demetrius; Jiao, Li

    2014-01-01

    The soluble receptor for advanced glycation end-products (sRAGE) is shown to mitigate pro-inflammatory effects triggered by ligation of RAGE with Nε-carboxymethyl-lysine (CML)-AGE or other ligands. We examined the associations among host, lifestyle, and genetic determinants of CML-AGE or sRAGE and risk of pancreatic cancer in the prospective ATBC Study. We obtained baseline exposure information, data on serological and genetic biomarkers from 141 patients with pancreatic cancer and 141 subcohort controls. Stepwise linear and logistic regression models were used for data analysis. Multiple linear regression analyses showed that CML-AGE concentrations were independently inversely correlated with the minor allele of rs640742 of DDOST, physical activity, alcohol consumption, diastolic blood pressure (BP), and positively correlated with heart rate, serum sRAGE and HDL concentrations (P < 0.05). sRAGE concentrations were independently inversely correlated with the 82Ser allele of rs2070600 of RAGE, age, body mass index, heart rate, and serum HDL; and positively correlated with serum CML-AGE, sucrose consumption, and diastolic BP (P < 0.05). The minor allele of rs1035786 of RAGE was associated with reduced risk of pancreatic cancer (any T compared with CC: multivariate OR = 0.61, 95% CI: 0.38-0.98). We identified host metabolic profile, lifestyle and genetic factors that explained approximately 50% of variability of CML-AGE or sRAGE in Finnish men smokers. The association between RAGE SNPs and pancreatic cancer risk warrants further investigation. PMID:25379135

  18. DNA Advanced Glycation End Products (DNA-AGEs) Are Elevated in Urine and Tissue in an Animal Model of Type 2 Diabetes.

    PubMed

    Jaramillo, Richard; Shuck, Sarah C; Chan, Yin S; Liu, Xueli; Bates, Steven E; Lim, Punnajit P; Tamae, Daniel; Lacoste, Sandrine; O'Connor, Timothy R; Termini, John

    2017-02-20

    More precise identification and treatment monitoring of prediabetic/diabetic individuals will require additional biomarkers to complement existing diagnostic tests. Candidates include hyperglycemia-induced adducts such as advanced glycation end products (AGEs) of proteins, lipids, and DNA. The potential for DNA-AGEs as diabetic biomarkers was examined in a longitudinal study using the Lepr(db/db) animal model of metabolic syndrome. The DNA-AGE, N(2)-(1-carboxyethyl)-2'-deoxyguanosine (CEdG) was quantified by mass spectrometry using isotope dilution from the urine and tissue of hyperglycemic and normoglycemic mice. Hyperglycemic mice (fasting plasma glucose, FPG, ≥ 200 mg/dL) displayed a higher median urinary CEdG value (238.4 ± 112.8 pmol/24 h) than normoglycemic mice (16.1 ± 11.8 pmol/24 h). Logistic regression analysis revealed urinary CEdG to be an independent predictor of hyperglycemia. Urinary CEdG was positively correlated with FPG in hyperglycemic animals and with HbA1c for all mice. Average tissue-derived CEdG was also higher in hyperglycemic mice (18.4 CEdG/10(6) dG) than normoglycemic mice (4.4 CEdG/10(6) dG). Urinary CEdG was significantly elevated in Lepr(db/db) mice relative to Lepr(wt/wt), and tissue CEdG values increased in the order Lepr(wt/wt) < Lepr(wt/db) < Lepr(db/db). These data suggest that urinary CEdG measurement may provide a noninvasive quantitative index of glycemic status and augment existing biomarkers for the diagnosis and monitoring of diabetes.

  19. Interaction of the S100A6 mutant (C3S) with the V domain of the receptor for advanced glycation end products (RAGE)

    SciTech Connect

    Mohan, Sepuru K. Gupta, Arun A. Yu, Chin

    2013-05-03

    Highlights: •The halo human S100A6 (C3S) NMR chemical shifts were assigned. •The interactions between S100A6m and RAGE V domain was investigated by ITC. •The residues involved in the S100A6m–RAGE V domain binding were mapped by {sup 1}H–{sup 15}N HSQC titration. •S100A6–RAGE V domain tetrameric complex model was generated from NMR studies. •The S100A6–RAGE V domain interface regions were elucidated based on HADDOCK model. -- Abstract: S100A6 is involved in several vital biological functions, such as calcium sensing and cell proliferation. It is a homodimeric protein that belongs to the S100 protein family. The receptor for advanced glycation end products (RAGE) has been shown to play a role in the progression of various disease conditions, such as diabetes and immune/inflammatory disorders. Information regarding the association of RAGE with S100 proteins at a molecular level is useful to understand the diversity of the RAGE signaling pathways. In this report, biomolecular NMR techniques were utilized for the resonance assignment of the C3S mutation in human S100A6 and characterizing its interaction with the RAGE V domain. Further binding affinity between S100A6m and the RAGE V domain was determined by isothermal titration calorimetric studies. HADDOCK was used to generate a heterotetramer model of the S100A6m–RAGE V domain complex. This model provides an important insights into the S100–RAGE cellular signaling pathway.

  20. Conditional overexpression of receptors for advanced glycation end-products in the adult murine lung causes airspace enlargement and induces inflammation.

    PubMed

    Stogsdill, Megan P; Stogsdill, Jeffrey A; Bodine, B Garrett; Fredrickson, Ali C; Sefcik, Tayler L; Wood, Tyler T; Kasteler, Stephen D; Reynolds, Paul R

    2013-07-01

    Receptors for advanced glycation end-products (RAGE) are multiligand surface receptors detected abundantly in pulmonary tissue. Our previous work revealed increased RAGE expression in cells and lungs exposed to tobacco smoke and RAGE-mediated cytokine expression via proinflammatory mechanisms involving NF-κB. RAGE expression is elevated in various pathological states, including chronic obstructive pulmonary disease; however, precise contributions of RAGE to the progression of emphysema and pulmonary inflammation in the adult lung are unknown. In the current study, we generated a RAGE transgenic (RAGE TG) mouse and conditionally induced adult alveolar epithelium to overexpress RAGE. RAGE was induced after the period of alveologenesis, from weaning (20 d of age) until animals were killed at 50, 80, and 110 days (representing 30, 60, and 90 d of RAGE overexpression). Hematoxylin and eosin staining and mean chord length revealed incremental dilation of alveolar spaces as RAGE overexpression persisted. TUNEL staining and electron microscopy confirmed increased apoptosis and blebbing of alveolar epithelium in lungs from RAGE TG mice when compared with control mice. Immunohistochemistry for matrix metalloproteinase 9 revealed an overall increase in matrix metalloproteinase 9, which correlated with decreased elastin expression in RAGE TG mice. Furthermore, RAGE TG mice manifested significant inflammation measured by elevated bronchoalveolar lavage protein, leukocyte infiltration, and secreted cytokines. These data support the concept that innovative transgenic mice that overexpress RAGE may model pulmonary inflammation and alveolar destabilization independent of tobacco smoke and validate RAGE signaling as a target pathway in the prevention or attenuation of smoke-related inflammatory lung diseases.

  1. Aliskiren attenuates bleomycin-induced pulmonary fibrosis in rats: focus on oxidative stress, advanced glycation end products, and matrix metalloproteinase-9.

    PubMed

    Abuelezz, Sally A; Hendawy, Nevien; Osman, Wesam M

    2016-08-01

    Pulmonary fibrosis is a progressive lung disorder with high mortality rate and limited successful treatment. This study was designed to assess the potential anti-oxidant and anti-fibrotic effects of aliskiren (Alsk) during bleomycin (BLM)-induced pulmonary fibrosis. Male Wistar rats were used as control untreated or treated with the following: a single dose of 2.5 mg/kg of BLM endotracheally and BLM and Alsk (either low dose 30 mg/kg/day or high dose 60 mg/kg/day), and another group was given Alsk 60 mg/kg/day alone. Alsk was given by gavage. Alsk anti-oxidant and anti-fibrotic effects were assessed. BLM significantly increased relative lung weight and the levels of lactate dehydrogenase and total and differential leucocytic count in bronchoalveolar lavage that was significantly ameliorated by high-dose Alsk treatment. As markers of oxidative stress, BLM caused a significant increase in the levels of lipid peroxides and nitric oxide accompanied with a significant decrease of superoxide dismutase and glutathione transferase enzymes. High-dose Alsk treatment restored these markers toward normal values. Alsk counteracted the overexpression of advanced glycation end products, matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinases-1 in lung tissue induced by BLM. Fibrosis assessed by measuring hydroxyproline content, which markedly increased in the BLM group, was also significantly reduced by Alsk. These were confirmed by histopathological and immunohistochemical examination which revealed that Alsk attenuates signs of pulmonary fibrosis and decreased the overexpressed MMP-9 and transforming growth factor β1. Collectively, these findings indicate that Alsk has a potential anti-fibrotic effect beside its anti-oxidant activity.

  2. Associations between Soluble Receptor for Advanced Glycation End Products (sRAGE) and S100A12 (EN-RAGE) with Mortality in Long-term Hemodialysis Patients.

    PubMed

    Jung, Eul Sik; Chung, Wookyung; Kim, Ae Jin; Ro, Han; Chang, Jae Hyun; Lee, Hyun Hee; Jung, Ji Yong

    2017-01-01

    Hemodialysis (HD) patients experience vascular calcification, ultimately leading to high mortality rates. Previously, we reported associations between soluble receptor for advanced glycation end products (sRAGEs) and extracellular newly identified RAGE-binding protein S100A12 (EN-RAGE) and vascular calcification. Here, we extended our observations, investigating whether these biomarkers may be useful for predicting cardiovascular morbidity and mortality in these subjects. Thus, we evaluated the relationship between sRAGE and S100A12 and mortality in long-term HD patients. This was a prospective observational cohort study in 199 HD patients from an extended analysis of our previous study. Plasma sRAGE, S100A12, comorbidities, and other traditional risk factors were investigated. The cumulative incidences for death using Cox proportional hazards regression were evaluated in multivariable analyses. The observation period was 44 months. During the observation period, 27 (13.6%) patients died. Univariate analysis demonstrated that S100A12 was correlated with diabetes (P = 0.040) and high-sensitivity C-reactive protein (hsCRP) (P = 0.006). In multivariable analyses, plasma sRAGE (hazard ratio [HR] = 1.155; 95% confidence interval [CI] = 0.612-2.183; P = 0.656) and S100A12 (HR = 0.960; 95% CI = 0.566-1.630; P = 0.881) were not associated with mortality in HD patients, although traditional predictors of mortality, including age, history of cardiovascular diseases (CVDs), and serum levels of albumin and hsCRP were related to mortality. Powerful predictors of mortality were age, CVD, and albumin levels. Plasma sRAGE and S100A12 may be weak surrogate markers for predicting all-cause mortality in patients undergoing HD, although S100A12 was partly related to diabetes and inflammation.

  3. Evaluation of the antioxidant and anti-glication effects of the hexane extract from Piper auritum leaves in vitro and beneficial activity on oxidative stress and advanced glycation end-product-mediated renal injury in streptozotocin-treated diabetic rats.

    PubMed

    Perez Gutierrez, Rosa Martha; Flores Cotera, Luis B; Gonzalez, Adriana Maria Neira

    2012-10-09

    The aim of this study was to investigate the antioxidant activity of hexane extracts from leaves of Piper auritum (HS). Eight complementary in vitro test methods were used, including inhibition of DPPH· radicals, nitric oxide, superoxide anion, ion-chelating, ABTS, oxygen radical absorbance capacity, β-carotene bleaching and peroxy radical scavenging. The results indicated that HS possesses high antioxidant activity. To add to these finding we tested the effect against oxidative stress in liver, pancreas and kidney in diabetic rats. Low levels of SOD, CAT, GPx and GSH in diabetic rats were reverted to near normal values after treatment with HS. These results suggest that P. auritum prevents oxidative stress, acting as a suppressor of liver cell damage. Given the link between glycation and oxidation, we proposed that HS might possess significant in vitro antiglycation activity. Our data confirmed the inhibitory effect of HS on bovine serum albumin, serum glycosylated protein, glycation of LDL, and glycation hemoglobin. The effect of HS on diabetic renal damage was investigated using streptozotocin-induced diabetic rats. The oral administration of HS at a dose of 200 and 400 mg/kg body weight/day for 28 days significantly reduced advanced glycation endproduct (AGE) formation, elevated renal glucose and thiobarbituric acid-reactive substance levels in the kidneys of diabetic rats. This implies that HS would alleviate the oxidative stress under diabetes through the inhibition of lipid peroxidation. These findings indicate that oxidative stress is increased in the diabetic rat kidney and that HS can prevent renal damage associated with diabetes by attenuating the oxidative stress.

  4. Method of Suppressing Sublimation in Advanced Thermoelectric Devices

    NASA Technical Reports Server (NTRS)

    Sakamoto, Jeffrey S. (Inventor); Caillat, Thierry (Inventor); Fleurial, Jean-Pierre (Inventor); Snyder, G. Jeffrey (Inventor)

    2009-01-01

    A method of applying a physical barrier to suppress thermal decomposition near a surface of a thermoelectric material including applying a continuous metal foil to a predetermined portion of the surface of the thermoelectric material, physically binding the continuous metal foil to the surface of the thermoelectric material using a binding member, and heating in a predetermined atmosphere the applied and physically bound continuous metal foil and the thermoelectric material to a sufficient temperature in order to promote bonding between the continuous metal foil and the surface of the thermoelectric material. The continuous metal foil forms a physical barrier to enclose a predetermined portion of the surface. Thermal decomposition is suppressed at the surface of the thermoelectric material enclosed by the physical barrier when the thermoelectric element is in operation.

  5. Vibration suppression of advanced space cryocoolers: an overview

    NASA Astrophysics Data System (ADS)

    Ross, Ronald G., Jr.

    2003-07-01

    Mechanical cryocoolers represent a significant enabling technology for precision space instruments by providing cryogenic temperatures for sensitive infrared, gamma-ray, and x-ray detectors. However, the vibration generated by the cryocooler's refrigeration compressor has long been identified as a critical integration issue. The key sensitivity is the extent to which the cooler's vibration harmonics excite spacecraft resonances and prevent on-board sensors from achieving their operational goals with respect to resolution and pointing accuracy. To reduce the cryocooler's vibration signature to acceptable levels, a variety of active vibration suppression technologies have been developed and implemented over the past 15 years. At this point, nearly all space cryocoolers have active vibration suppression systems built into their drive electronics that reduce the peak unbalanced forces to less than 1% of their original levels. Typical systems of today individually control the vibration in each of the cryocoolers lowest drive harmonics, with some controlling as many as 16 harmonics. A second vibration issue associated with cryocoolers is surviving launch. Here the same pistons and coldfingers that generate vibration during operation are often the most critical elements in terms of surviving high input acceleration levels. Since electrical power is generally not available during launch, passive vibration suppression technologies have been developed. Common vibration damping techniques include electrodynamic braking via shorted motor coils and the use of particle dampers on sensitive cryogenic elements. This paper provides an overview of the vibration characteristics of typical linear-drive space cryocoolers, outlines their history of development, and presents typical performance of the various active and passive vibration suppression systems being used.

  6. The effects of Advanced Glycation End Products (RAGE)-374T/A and Gly82Ser variants and soluble-RAGE levels to obesity in children.

    PubMed

    Kucukhuseyin, O; Ozgen, T; Karagedik, E H; Cesur, Y; Yilmaz Aydogan, H; Yaylim, I; Ergen, H A

    2016-04-30

    In recent years, studies related to advanced glycation end products (AGE) and their interaction with their receptors (RAGE) have advanced our knowledge of the roles of these molecules in different diseases. However, studies concerning AGE-RAGE interaction in obesity are limited and the results are conflicting. RAGE gene is located on 6p21.3, has several polymorphic sites including -374T/A, a functional polymorphism in the promoter region, and Gly82Ser, present within the ligand-binding domain. In the present study, the determination of possible risks in the development of obesity according to RAGE polymorhisms and plasma levels of RAGE (sRAGE) was aimed. 87 obese and 78 healthy children were included in this study. Genomic DNA was isolated with salting-out procedure. RAGE polymorphisms were analyzed by PCR based techniques. In contrast to Gly82Ser, -374T/A allelic and genotypic frequencies were not different between study groups. Ser(SerSer+GlySer genotype) allele frequency was higher in obese cases than controls (74.20%→25.80%,OR:2.573,95%CI:1.789-3.699;p<0.01). In obese cases, blood glycose (92.50±2.80→87.00±1.16; p=0.025) and HDL-C (46.14±2.75→39.84±1.82;p=0.057) levels were higher than TT genotype carriers. As for Gly82Ser polymorphism, HDL-C (p=0.004) and FT4 (p=0.020) levels were different in obese cases, the order was SerSer>GlySer>GlyGly for HDL-C, and opposite for FT4. Besides, Ser carriers had lower insulin (p=0.038) and homa-IR (p=0.081) levels than GG genotype. sRAGE levels were different between obese and control seperately or in combination with RAGE polymorphisms (p<0.05), the order of sRAGE was TT>TA>AA for -374T/A and SerSer>GlyGly>GlySer for Gly82Ser. According to our results SerSer genotype could have significant effects on sRAGE levels, and increased sRAGE levels and Gly82Ser polymorphism either combinatorially or seperately increased the propensity towards obesity.

  7. Nutrition and aging skin: sugar and glycation.

    PubMed

    Danby, F William

    2010-01-01

    The effect of sugars on aging skin is governed by the simple act of covalently cross-linking two collagen fibers, which renders both of them incapable of easy repair. Glucose and fructose link the amino acids present in the collagen and elastin that support the dermis, producing advanced glycation end products or "AGEs." This process is accelerated in all body tissues when sugar is elevated and is further stimulated by ultraviolet light in the skin. The effect on vascular, renal, retinal, coronary, and cutaneous tissues is being defined, as are methods of reducing the glycation load through careful diet and use of supplements.

  8. Effect of dietary prebiotic supplementation on advanced glycation, insulin resistance and inflammatory biomarkers in adults with pre-diabetes: a study protocol for a double-blind placebo-controlled randomised crossover clinical trial

    PubMed Central

    2014-01-01

    Background Advanced glycation endproducts (AGEs) contribute to the development of vascular complications of diabetes and have been recently implicated in the pathogenesis of diabetes. Since AGEs are generated within foodstuffs upon food processing, it is increasingly recognised that the modern diet is replete with AGEs. AGEs are thought to stimulate chronic low-grade inflammation and promote oxidative stress and have been linked to the development of insulin resistance. Simple therapeutic strategies targeted at attenuating the progression of chronic low-grade inflammation and insulin resistance are urgently required to prevent or slow the development of type 2 diabetes in susceptible individuals. Dietary modulation of the human colonic microbiota has been shown to confer a number of health benefits to the host, but its effect on advanced glycation is unknown. The aim of this article is to describe the methodology of a double-blind placebo-controlled randomised crossover trial designed to determine the effect of 12 week consumption of a prebiotic dietary supplement on the advanced glycation pathway, insulin sensitivity and chronic low-grade inflammation in adults with pre-diabetes. Methods/Design Thirty adults with pre-diabetes (Impaired Glucose Tolerance or Impaired Fasting Glucose) aged between 40–60 years will be randomly assigned to receive either 10 grams of prebiotic (inulin/oligofructose) daily or 10 grams placebo (maltodextrin) daily for 12 weeks. After a 2-week washout period, study subjects will crossover to receive the alternative dietary treatment for 12 weeks. The primary outcome is the difference in markers of the advanced glycation pathway carboxymethyllysine (CML) and methylglyoxal (MG) between experimental and control treatments. Secondary outcomes include HbA1c, insulin sensitivity, lipid levels, blood pressure, serum glutathione, adiponectin, IL-6, E-selectin, myeloperoxidase, C-reactive protein, Toll-like Receptor 4 (TLR4), soluble receptor

  9. The neuroprotective role of metformin in advanced glycation end product treated human neural stem cells is AMPK-dependent.

    PubMed

    Chung, Ming-Min; Chen, Yen-Lin; Pei, Dee; Cheng, Yi-Chuan; Sun, Binggui; Nicol, Christopher J; Yen, Chia-Hui; Chen, Han-Min; Liang, Yao-Jen; Chiang, Ming-Chang

    2015-05-01

    Diabetic neuronal damage results from hyperglycemia followed by increased formation of advanced glycosylation end products (AGEs), which leads to neurodegeneration, although the molecular mechanisms are still not well understood. Metformin, one of the most widely used anti-diabetic drugs, exerts its effects in part by activation of AMP-activated protein kinase (AMPK). AMPK is a critical evolutionarily conserved enzyme expressed in the liver, skeletal muscle and brain, and promotes cellular energy homeostasis and biogenesis by regulating several metabolic processes. While the mechanisms of AMPK as a metabolic regulator are well established, the neuronal role for AMPK is still unknown. In the present study, human neural stem cells (hNSCs) exposed to AGEs had significantly reduced cell viability, which correlated with decreased AMPK and mitochondria associated gene/protein (PGC1α, NRF-1 and Tfam) expressions, as well as increased activation of caspase 3 and 9 activities. Metformin prevented AGEs induced cytochrome c release from mitochondria into cytosol in the hNSCs. Co-treatment with metformin significantly abrogated the AGE-mediated effects in hNSCs. Metformin also significantly rescued hNSCs from AGE-mediated mitochondrial deficiency (lower ATP, D-loop level, mitochondrial mass, maximal respiratory function, COX activity, and mitochondrial membrane potential). Furthermore, co-treatment of hNSCs with metformin significantly blocked AGE-mediated reductions in the expression levels of several neuroprotective genes (PPARγ, Bcl-2 and CREB). These findings extend our understanding of the molecular mechanisms of both AGE-induced neuronal toxicity, and AMPK-dependent neuroprotection by metformin. This study further suggests that AMPK may be a potential therapeutic target for treating diabetic neurodegeneration.

  10. Osmotic stress is accompanied by protein glycation in Arabidopsis thaliana

    PubMed Central

    Paudel, Gagan; Bilova, Tatiana; Schmidt, Rico; Greifenhagen, Uta; Berger, Robert; Tarakhovskaya, Elena; Stöckhardt, Stefanie; Balcke, Gerd Ulrich; Humbeck, Klaus; Brandt, Wolfgang; Sinz, Andrea; Vogt, Thomas; Birkemeyer, Claudia; Wessjohann, Ludger; Frolov, Andrej

    2016-01-01

    Among the environmental alterations accompanying oncoming climate changes, drought is the most important factor influencing crop plant productivity. In plants, water deficit ultimately results in the development of oxidative stress and accumulation of osmolytes (e.g. amino acids and carbohydrates) in all tissues. Up-regulation of sugar biosynthesis in parallel to the increasing overproduction of reactive oxygen species (ROS) might enhance protein glycation, i.e. interaction of carbonyl compounds, reducing sugars and α-dicarbonyls with lysyl and arginyl side-chains yielding early (Amadori and Heyns compounds) and advanced glycation end-products (AGEs). Although the constitutive plant protein glycation patterns were characterized recently, the effects of environmental stress on AGE formation are unknown so far. To fill this gap, we present here a comprehensive in-depth study of the changes in Arabidopsis thaliana advanced glycated proteome related to osmotic stress. A 3 d application of osmotic stress revealed 31 stress-specifically and 12 differentially AGE-modified proteins, representing altogether 56 advanced glycation sites. Based on proteomic and metabolomic results, in combination with biochemical, enzymatic and gene expression analysis, we propose monosaccharide autoxidation as the main stress-related glycation mechanism, and glyoxal as the major glycation agent in plants subjected to drought. PMID:27856706

  11. Immunological evidence that non-carboxymethyllysine advanced glycation end-products are produced from short chain sugars and dicarbonyl compounds in vivo.

    PubMed Central

    Takeuchi, M.; Makita, Z.; Bucala, R.; Suzuki, T.; Koike, T.; Kameda, Y.

    2000-01-01

    BACKGROUND: The Maillard reaction that leads to the formation of advanced glycation end-products (AGE) plays an important role in the pathogenesis of angiopathy in diabetic patients and in the aging process. Recently, it was proposed that AGE were not only created by glucose, but also by dicarbonyl compounds derived from the Maillard reaction, autoxidation of sugars and other metabolic pathways of glucose. In this study, we developed four types of non-carboxymethyllysine (CML) anti-AGE antibodies that recognized proteins modified by incubation with short chain sugars and dicarbonyl compounds. MATERIALS AND METHODS: AGE-modified serum albumins were prepared by incubation of rabbit serum albumin with glyceraldehyde, glycolaldehyde, methylglyoxal or glyoxal. After immunization of rabbits, four types of AGE-specific antisera were obtained that were specific for the AGE modification. To separate non-CML AGE antibodies (Ab) (non-CML AGE-Ab-2, -3, -4, and -5), these anti-AGE antisera were subjected to affinity chromatography on a matrix coupled with four kinds of AGE bovine serum albumin (BSA) or CML-BSA. These non-CML AGE antibodies were used to investigate the AGE content of serum obtained from diabetic patients on hemodialysis. RESULTS: Characterization of the four types of non-CML AGE antibodies obtained by immunoaffinity chromatography was performed by competitive ELISA and immunoblot analysis. Non-CML AGE-Ab-2 crossreacted with the protein modified by glyceraldehyde or glycolaldehyde. Non-CML AGE-Ab-3 and -Ab-4 specifically cross-reacted with protein modified by glycolaldehyde and methylglyoxal, respectively. NonCML AGE-Ab-5 cross-reacted with protein modified with glyoxal as well as methylglyoxal and glycolaldehyde. Three kinds of non-CML AGE (AGE-2, -4, and -5) were detected in diabetic serum as three peaks with apparent molecular weights of 200, 1.15, and 0.85 kD; whereas, AGE-3 was detected as two peaks with apparent molecular weights of 200 and 0.85 k

  12. Low Levels of IgM Antibodies against an Advanced Glycation Endproduct-Modified Apolipoprotein B100 Peptide Predict Cardiovascular Events in Nondiabetic Subjects.

    PubMed

    Engelbertsen, Daniel; Vallejo, Jenifer; Quách, Tâm Dan; Fredrikson, Gunilla Nordin; Alm, Ragnar; Hedblad, Bo; Björkbacka, Harry; Rothstein, Thomas L; Nilsson, Jan; Bengtsson, Eva

    2015-10-01

    Increased glucose levels are associated with the generation of advanced glycation endproduct (AGE) modifications. Interaction between AGE-modified plaque components and immune cells is believed to have an important role in the development of vascular complications in diabetes. Methylglyoxal (MGO) is one type of reactive aldehyde that gives rise to AGE modification. The present study analyzed whether autoantibodies against MGO-modified epitopes of the low-density lipoprotein apolipoprotein B (apoB) 100 predict cardiovascular events. A library consisting of 302 peptides comprising the complete apoB100 molecule was screened to identify peptides targeted by MGO-specific autoantibodies. Peptide (p) 220 (apoB amino acids 3286-3305) was identified as a major target. Baseline IgM and IgG against MGO-peptide 220 (p220) were measured in 700 individuals from the Malmö Diet and Cancer Cohort. A total of 139 cardiovascular events were registered during the 15-y follow-up period. Controlling for major cardiovascular risk factors demonstrated that subjects in the lowest tertile of MGO-p220 IgM had an increased risk for cardiovascular events (hazard ratio [95% confidence interval]: 2.07 [1.22-3.50]; p(trend) = 0.004). Interestingly, the association between MGO-p220 IgM and cardiovascular events remained and even tended to become stronger when subjects with prevalent diabetes were excluded from the analysis (2.51 [1.37-4.61]; p(trend) = 0.002). MGO-p220 IgM was inversely associated with blood glucose, but not with oxidized low-density lipoprotein. Finally, we demonstrate that anti-MGO-p220 IgM is produced by B1 cells. These data show that subjects with low levels of IgM recognizing MGO-modified p220 in apoB have an increased risk to develop cardiovascular events and that this association is present in nondiabetic subjects.

  13. Assessment of the concentrations of various advanced glycation end-products in beverages and foods that are commonly consumed