High Advanced Glycation End-products Research Articles

APOE ε4 Carriers Have a Greater Propensity to Glycation and sRAGE Which Is Further Influenced by RAGE G82S Polymorphism.

APOE ε4 allele is an established risk factor for Alzheimer's disease and hypercholesterolemia. However, its association with metabolic and genetic risk factors related to glycation is not clear. We tested the hypothesis that, apart from high plasma cholesterol, APOE ε4 carriers may also have higher advanced glycation end products (AGEs) and total soluble extracellular domain of RAGE (sRAGE) and that these biomarkers may be modified by the common Gly82Ser (G82S) polymorphism (rs2070600) in the RAGE gene. To test this, we measured these biomarkers in 172 healthy cognitively normal individuals, of which 32 were APOE ε4 carriers and 140 noncarriers. APOE ε4 carriers showed higher levels of cholesterol (p < .001), glyoxal (p < .001), fluorescent AGEs (p < .001), Nε-carboxymethyllysine (p < .001) and sRAGE (p = .018) when compared to noncarriers. Furthermore, sRAGE was also higher in those that did not carry the A allele of the RAGE gene that codes for serine instead of glycine (p = .034). Our study indicates that APOE ε4 carriers have a greater propensity to glycation than noncarriers which may further increase their risk for diabetes and dementia. The increased sRAGE levels in APOE ε4 carriers suggests a defensive response against AGEs that may be further influenced by the RAGE G82S polymorphism.

Abstract 619: Dietary advanced glycation end-products and postmenopausal breast cancer risk in the NIH AARP diet and health study

Abstract Purpose: Advanced glycation end-products (AGE) are hypothesized to be involved in carcinogenesis. We analyzed dietary AGE intake in relation to invasive breast cancer (BC) to advance our knowledge of the impact of diet on BC risk. Methods: Dietary AGE intake was estimated from the food-frequency questionnaire in postmenopausal women in the NIH AARP Diet and Health study, prospective cohort (n=183,548). Incident BC cases were identified through linkage with state cancer registries. Cox proportional hazards regression models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for developing BC according to quintiles of AGE levels. Multivariate regression models were adjusted for established BC risk factors. Results: During a mean follow-up of 12.8 years, 9,851 BCs (1,978 advanced stage) were identified. Median daily AGE intake was 5,932 KU/1,000 kcal (10th- 90th percentile, 3,555 - 8,644). Women with higher AGE intake tended to have lower education level, higher BMI, younger age at menarche, menopause, first birth, more children, less physical activity, current smoking and higher total fat and meat intake. AGE intake was associated with increased risk of BC in the multivariate model 1, but the association was attenuated and no longer significant after adjusting for total meat and fat intakes (Table). The association between AGE intake and BC did not differ by BMI, hormone therapy use, or alcohol consumption. AGE intake was not related to BC hormone receptor status, histologic type, or grade. However, AGE intake was associated with increased risks of advanced stage tumors (highest vs. lowest quintile of AGE intake, RR 1.37 95% CI 1.09-1.74) even after controlling for total meat and fat intakes. The risk of advanced stage BC increased by 14% (RR 1.14 95% CI 1.04-1.25 in multivariate model 2) per 2,500 KU/1,000 kcal increase in AGE intake. Conclusions: Dietary AGEs may play a role in the development of postmenopausal BC, particularly in advanced stage BC. Relative Risks (95% CI) of breast cancer for quintiles of AGE intakeQuintiles of AGE intake12345P valueContinuous AGETotal invasive breast cancerNo. of cases1,8992,0231,9321,9952,002Age-adjusted model1 reference1.07 (1.01-1.14)1.03 (0.97-1.10)1.08 (1.01-1.15)1.10 (1.04-1.17).0051.05 (1.02-1.07)Multivariate model 11 reference1.06 (0.99-1.13)1.01 (0.95-1.08)1.05 (0.99-1.12)1.09 (1.02-1.16).031.04 (1.02-1.07)Multivariate model 21 reference1.00 (0.93-1.08)0.94 (0.86-1.02)0.96 (0.88-1.06)1.00 (0.90-1.11).991.03 (0.99-1.08)StageLocalizedNo. of cases1,0211,0169741,001989Age-adjusted model1 reference1.00 (0.92-1.09)0.97 (0.88-1.05)1.00 (0.92-1.09)1.01 (0.92-1.10).891.02 (0.99-1.06)Multivariate model 11 reference0.99 (0.90-1.08)0.95 (0.87-1.04)0.98 (0.90-1.07)1.00 (0.92-1.10).921.02 (0.98-1.06)Multivariate model 21 reference0.90 (0.81-0.99)0.84 (0.75-0.94)0.86 (0.76-0.98)0.90 (0.78-1.04).321.02 (0.96-1.09)Distant/RegionalNo. of cases341414377408438Age-adjusted model1 reference1.22 (1.06-1.41)1.12 (0.97-1.29)1.22 (1.05-1.41)1.33 (1.15-1.53)&amp;lt;.0011.11 (1.05-1.17)Multivariate model 11 reference1.21 (1.04-1.39)1.10 (0.94-1.27)1.18 (1.02-1.37)1.28 (1.11-1.48).0041.09 (1.03-1.16)Multivariate model 21 reference1.25 (1.06-1.47)1.15 (0.95-1.40)1.25 (1.02-1.54)1.37 (1.09-1.74).021.14 (1.04-1.25) Citation Format: Lindsay L. Peterson, Seho Park, Yikyung Park, Narges Anbardar, David Turner. Dietary advanced glycation end-products and postmenopausal breast cancer risk in the NIH AARP diet and health study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 619.

Association of Dietary Advanced Glycation End Products with Metabolic Syndrome in Young Mexican Adults.

Background: Consumption of dietary advanced glycation end products is linked to metabolic syndrome. The objective was to describe the association between dietary advanced glycation end products intake and metabolic syndrome in young Mexican adults. Methods: The present was a cross-sectional study in 126 Mexican adults 18–35 years old evaluating metabolic syndrome through the harmonized criteria. Macronutrients and dietary advanced glycation end products intake were estimated through three 24-hour dietary recalls and food composition tables. Association between metabolic syndrome and high advanced glycation end products intake (≥10,000 kU/day) was evaluated through three logistic regression models adjusted by sex, age, family history of cardiometabolic diseases and energy intake. Results: Subjects with a higher advanced glycation end products intake were more likely to have impaired fasting glucose (OR: 4.91, 95% CI 1.29–18.60, p < 0.05) and metabolic syndrome (OR: 2.67, 95% CI 0.96–7.44, p = 0.059) than those participants with low consumption of these products after adjustment of sex, age, family history of cardiovascular disease and energy intake. Conclusions: High intake of dietary advanced glycation end products was significantly associated with impaired fasting glucose and marginally with metabolic syndrome in young Mexican adults regardless of sex, age, family history of cardiovascular disease and energy intake.

The ratio of AGE to sRAGE independently associated with albuminuria in hypertensive patients

BackgroundSoluble receptor for advanced glycation end-products (sRAGE) and advanced glycation end-products (AGE) have been associated with risks of cardiovascular disease. Because sRAGE is regarded as a scavenger to AGE, we hypothesized that the ratio of AGE to sRAGE (AGE/sRAGE) is associated with albuminuria in hypertensive patients.MethodsIn this cross-sectional study, a total of 104 patients with essential hypertension were recruited. Hypertension was defined as a systolic blood pressure ≥ 140 mmHg, a diastolic blood pressure ≥ 90 mmHg, or use of antihypertensive treatment. Albuminuria was defined as albumin excretion rate ≧ 20 μg/min. Multivariate logistic regression analyses were performed to evaluate the association between AGE/sRAGE and albuminuria.ResultsAmong the 104 patients, 30 (28.8%) patients had albuminuria and 74 (71.2%) patients did not. Patients with albuminuria had higher AGE (2.15 vs. 1.71 μg/mL), lower sRAGE (424.5 vs. 492.5 pg/ml) and higher AGE/sRAGE (3.79 vs. 3.29 μg/pg) than those without albuminuria. Multivariate logistic regression model revealed that AGE/sRAGE (OR = 1.131, 95% CI = 1.001–1.278, P = 0.048) was independently associated with albuminuria. There was no significant relationship between AGE and sRAGE alone with albuminuria.ConclusionThis study suggests that the ratio of AGE to sRAGE may be a surrogate biomarker for microvascular injury. Further prospective studies of the prognostic value of the ratio in relation to microvasular injury are needed.

Advanced glycation end-products suppress autophagic flux in podocytes by activating mammalian target of rapamycin and inhibiting nuclear translocation of transcription factor EB.

Insufficient autophagy in podocytes is related to podocyte injury in diabetic nephropathy (DN). Advanced glycation end‐products (AGEs) are major factors of podocyte injury in DN. However, the role and mechanism of AGEs in autophagic dysfunction remain unknown. We investigated autophagic flux in AGE‐stimulated cultured podocytes using multiple assays: western blotting, reverse transcription–quantitative PCR, immunofluorescence staining, and electron microscopy. We also utilized chloroquine and a fluorescent probe to monitor the formation and turnover of autophagosomes. Mice of the db/db strain were used to model diabetes mellitus (DM) with high levels of AGEs. To mimic DM with normal levels of AGEs as a control, we treated db/db mice with pyridoxamine to block AGE formation. AGEs impaired autophagic flux in the cultured podocytes. Compared with db/db mice with normal AGEs but high glucose levels, db/db mice with high AGEs and high glucose levels exhibited lower autophagic activity. Aberrant autophagic flux was related to hyperactive mammalian target of rapamycin (mTOR), a major suppressor of autophagy. Pharmacologic inhibition of mTOR activity restored impaired autophagy. AGEs inhibited the nuclear translocation and activity of the pro‐autophagic transcription factor EB (TFEB) and thus suppressed transcription of its several autophagic target genes. Conversely, TFEB overexpression prevented AGE‐induced autophagy insufficiency. Attenuating mTOR activity recovered TFEB nuclear translocation under AGE stimulation. Co‐immunoprecipitation assays further demonstrated the interaction between mTOR and TFEB in AGE‐stimulated podocytes and in glomeruli from db/db mice. In conclusion, AGEs play a crucial part in suppressing podocyte autophagy under DM conditions. AGEs inhibited the formation and turnover of autophagosomes in podocytes by activating mTOR and inhibiting the nuclear translocation of TFEB. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The AGP-PPARγ axis promotes oxidative stress and diabetic endothelial cell dysfunction.

Alkyl-glycerophosphate (AGP) accumulates in atherogenic oxidized-LDL and human atherosclerotic plaques and is a potent agonist of peroxisome-proliferator-activated receptor-gamma (PPARγ). Recent studies suggest a potential regulatory role for PPARγ in endothelial nitric oxide synthase (eNOS) expression/activation and nitrogen oxide (NO) generation in the vascular endothelium. Importantly, eNOS-induced NO and advanced glycation end-products (AGEs) are involved in blood-vessel damage, and diabetic patients exhibit high serum NO and AGE levels; however, the effect of AGP on NO- and AGE-mediated endothelium dysfunction remains unknown. Investigation of the AGP-specific effects on NO- and AGE-mediated dysfunction and the underlying molecular mechanisms revealed that AGP upregulated eNOS expression and NO production, and that eNOS silencing and PPARγ antagonism inhibited AGP-mediated eNOS upregulation and NO production. Moreover, AGP-PPARγ-axis-mediated NO production promoted the generation of reactive oxygen species and AGE formation. These results suggested that AGP plays a significant role in the initiation/progression of diabetes-related atherosclerosis through PPARγ activation.

Dietary advanced glycation end-product consumption leads to mechanical stiffening of murine intervertebral discs.

ABSTRACTBack pain is a leading cause of disability and is strongly associated with intervertebral disc (IVD) degeneration. Reducing structural disruption and catabolism in IVD degeneration remains an important clinical challenge. Pro-oxidant and structure-modifying advanced glycation end-products (AGEs) contribute to obesity and diabetes, which are associated with increased back pain, and accumulate in tissues due to hyperglycemia or ingestion of foods processed at high heat. Collagen-rich IVDs are particularly susceptible to AGE accumulation due to their slow metabolic rates, yet it is unclear whether dietary AGEs can cross the endplates to accumulate in IVDs. A dietary mouse model was used to test the hypothesis that chronic consumption of high AGE diets results in sex-specific IVD structural disruption and functional changes. High AGE diet resulted in AGE accumulation in IVDs and increased IVD compressive stiffness, torque range and failure torque, particularly for females. These biomechanical changes were likely caused by significantly increased AGE crosslinking in the annulus fibrosus, measured by multiphoton imaging. Increased collagen damage measured with collagen hybridizing peptide did not appear to influence biomechanical properties and may be a risk factor as these animals age. The greater influence of high AGE diet on females is an important area of future investigation that may involve AGE receptors known to interact with estrogen. We conclude that high AGE diets can be a source for IVD crosslinking and collagen damage known to be important in IVD degeneration. Dietary modifications and interventions that reduce AGEs warrant further investigation and may be particularly important for diabetics, in whom AGEs accumulate more rapidly.

Dietary Advanced Glycation End Products Have Sex- and Age-Dependent Effects on Vertebral Bone Microstructure and Mechanical Function in Mice.

Back pain is a leading cause of global disability that can arise from vertebral fracture and osteoporosis. Although poor general health and obesity are among the strongest risk factors for back pain, there is remarkably little known about how diet influences spinal diseases. Advanced glycation end-products (AGEs) are implicated in increased fracture risk, yet no studies investigated how dietary AGEs affect spinal health. We tested the hypothesis that high dietary AGE ingestion will diminish vertebral structure and function in a sex- and age-dependent manner. Female and male mice were fed low-AGE (L-AGE) or high-AGE (H-AGE) isocaloric diets for 6 and 18 months and multiple measurements of bone structure and function were taken. AGE levels in serum and cortical vertebrae were increased only for 6-month-old H-AGE female mice while blood glucose and body weight remained normal for all animals. When fed an H-AGE diet, 6-month-old female mice had inferior vertebral trabecular structure with decreased bone mineral density (BMD) and bone volume fraction. Biomechanical testing and analytical modeling further showed functional deterioration in 6-month-old H-AGE females with reduced shear and compression moduli, and maximum load to failure. At 18 months, H-AGE mice of both sexes had significant but small decreases in cortical BMD and thickness, yet functional biomechanical behaviors were not distinguishable from other aging changes. We conclude that an H-AGE diet, without diabetic or overweight conditions, diminished vertebral microstructure, mechanical behaviors, and fracture resistance in young female mice in a manner suggesting accelerated bone aging. © 2017 American Society for Bone and Mineral Research.

Increased liver AGEs induce hepatic injury mediated through an OST48 pathway

The protein oligosaccharyltransferase-48 (OST48) is integral to protein N-glycosylation in the endoplasmic reticulum (ER) but is also postulated to act as a membrane localised clearance receptor for advanced glycation end-products (AGE). Hepatic ER stress and AGE accumulation are each implicated in liver injury. Hence the objective of this study was to increase the expression of OST48 and examine the effects on hepatic function and structure. Groups of 8 week old male mice (n = 10–12/group) over-expressing the gene for OST48, dolichyl-diphosphooligosaccharide-protein glycosyltransferase (DDOST+/−), were followed for 24 weeks, while randomised to diets either low or high in AGE content. By week 24 of the study, either increasing OST48 expression or consumption of high AGE diet impaired liver function and modestly increased hepatic fibrosis, but their combination significantly exacerbated liver injury in the absence of steatosis. DDOST+/− mice had increased both portal delivery and accumulation of hepatic AGEs leading to central adiposity, insulin secretory defects, shifted fuel usage to fatty and ketoacids, as well as hepatic glycogen accumulation causing hepatomegaly along with hepatic ER and oxidative stress. This study revealed a novel role of the OST48 and AGE axis in hepatic injury through ER stress, changes in fuel utilisation and glucose intolerance.

Association between advanced glycation end-products and functional performance in Alzheimer's disease and mixed dementia.

People with Alzheimer's disease (AD) experience, in addition to the progressive loss of cognitive functions, a decline in functional performance such as mobility impairment and disability in activities of daily living (ADL). Functional decline in dementia is mainly linked to the progressive brain pathology. Peripheral biomechanical changes by advanced glycation end-products (AGEs) have been suggested but have yet to be thoroughly studied. A multi-center, longitudinal, one-year follow-up cohort study was conducted in 144 people with early stage AD or mixed Alzheimer's/Vascular dementia. Linear mixed model analyses was used to study associations between AGE-levels (AGE reader) and mobility (Timed Up and Go), and ADL (Groningen Activity Restriction Scale and Barthel index), respectively. A significant association between AGE levels and mobility (β = 3.57, 95%CI: 1.43-5.73) was revealed; however, no significant association between AGE levels and ADL was found. Over a one-year time span, mean AGE levels significantly increased, and mobility and ADL performance decreased. Change in AGE levels was not significantly correlated with change in mobility. This study indicates that high AGE levels could be a contributing factor to impaired mobility but lacks evidence for an association with ADL decline in people with early stage AD or mixed dementia. Future research is necessary on the reduction of functional decline in dementia regarding the effectiveness of interventions such as physical activity programs and dietary advice possibly in combination with pharmacologic strategies targeting AGE accumulation.

Methylglyoxal-Derived Advanced Glycation Endproducts in Multiple Sclerosis.

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.

Long-term administration of advanced glycation end-product stimulates the activation of NLRP3 inflammasome and sparking the development of renal injury

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.

Advanced glycation end products, fibroblast growth factors and the development of atherosclerosis in patients with diabetes

Introduction. Atherosclerotic processes are more pronounced at diabetes mellitus (DM). Chronic hyperglycemia activated pathological mechanisms of restructuring the connective tissue, including the vascular wall. Fibroblasts are the main cellular components. Activation of the transforming growth factor (TGFß1), basic fibroblast growth factor (ß-FGF), produced by fibroblasts, inflammatory markers (interleukin-6 (IL-6), tumor necrosis factor (α-TNF), advanced glycation endproducts (AGE) and their receptors (rAGE), may have important prognostic value.Objective. To investigate the level AGE, TGFß1 and ß-FGF in patients with severity atherosclerosis coronary artery disease (CAD), to compare with normal blood glucose and DM.Material and methods. The study involved two groups of patients with CAD: 56 patients of the first group had normal blood glucose and 78 patients suffered from DM type 2. The degree of coronary atherosclerosis was determined by coronary angiography (CAG) in all patients. The blood samples were collected from the aorta during CAG and cubital vein simultaneously, immediately centrifuged (15000g*min), supernatants were stored at –70*C until analysis were done. Serum was analyzed by ELISA (IFA). The critical significance level (p) for statistical hypothesis testing was set at &lt;0.05.Results. Average β-FGF, TGF-ß1, AGE, RAGE in the second group was significantly higher than in the first (p&lt;0.005). Increased level of the AGE, RAGE and TGFß1 was positive correlated with low-density lipoprotein and triglycerides (R=0,049, p&lt;0.005). IL-6 was significantly higher in the second group. There was the significant correlative relationship between the levels AGE, RAGE, TGFß1, ß-FGF and IL-6 with DM duration (R=-0,120; p=0.009), direct association with HbA1C (R=0,429; p=0.006). There were significantly higher level of the AGE, TGFß1 and ß-FGF in aortic blood than in peripheral venous blood p&lt;0,005). IL-6 level had opposite features: serum IL-6 was higher in venous than arterial blood. The patients with DM had three-vessel disease often (73%) then the patients without DM (R = 0,021, p&lt;0.005), which was direct correlated with level TGFß1 (R = 0,03, p&lt;0.005). There weren`t any differences in α-TNF level between two groups.Discussion. High AGE, TGFß1 level and positive correlation with atherogenic lipids may indicate the role of the connective tissue remodeling in pathogenesis of the coronary atherosclerosis. As the longer DM duration led to increasing AGE, TGFß1 and IL-6 levels the chronic hyperglycemia can restructure the vascular wall. Higher AGE, TGFß1 and ß-FGF levels in aorta then in peripheral blood may show the involvement of the cardiomyocytes in these growth factors metabolism.Conclusion. DM existence with CAD was characterized by higher AGE, RAGE, TGFß1 and IL-6 levels, which was direct correlated with the atherogenic lipids. Patients with type 2 DM and CAD had more severe coronary artery disease.

Effect of high glucose, Porphyromonas gingivalis lipopolysaccharide and advanced glycation end-products on production of interleukin-6/-8 by gingival fibroblasts.

It is known that chronic periodontal infection can magnify the cytokine responses in patients with diabetes. Hyperglycemia increases the proinflammatory status, including the levels of advanced glycation end-products (AGEs), in patients with periodontitis. However, whether AGEs have additional effects on the production of those proinflammatory cytokines in diabetic patients with periodontitis is still unknown. To examine in vitro the effect of hyperglycemia and AGEs on the amounts of interleukin (IL)-6 and IL-8 produced in periodontally infected gingiva, human gingival fibroblasts (HGFs) were stimulated with glucose, AGE-modified bovine serum albumin (AGE-BSA) and Porphyromonas gingivalis LPS in the present study. Primary culture of HGFs was incubated with various concentrations of AGE-BSA (0, 50, 100 and 200 μg/mL) and LPS (0, 10, 100 or 1000 ng/mL) at two different glucose concentrations - normal glucose (5 mm) and high glucose (25 mm). The amounts of IL-6 and IL-8 produced by HGFs were evaluated using ELISA. Expression of the AGE receptor on HGFs was determined by flow cytometry. High glucose stimulated a significant increase in the production of IL-6 and IL-8 by HGFs compared with normal glucose. This enhanced production of IL-6 and IL-8 could also be observed in the presence of LPS and/or AGE-BSA. When both LPS and AGE-BSA were present, especially at high concentrations (≥ 500 μg/mL of LPS and ≥ 25 μg/mL of AGE-BSA), a synergistic effect on IL-8 production was found in the high-glucose condition. A synergistic effect of the production of IL-8 could be induced in HGFs with the combination of high glucose, LPS and AGEs.

Advanced Glycation Endproducts and Bone Material Properties in Type 1 Diabetic Mice.

Fractures, particularly at the lower extremities and hip, are a complication of diabetes. In both type 1 (T1D) and type 2 diabetes (T2D), fracture risk is disproportionately worse than that predicted from the measurement of bone mineral density. Although an explanation for this discrepancy is the presence of organic matrix abnormalities, it has not been fully elucidated how advanced glycation endproducts (AGEs) relate to bone deterioration at both the macroscopic and microscopic levels. We hypothesized that there would be a relationship between skeletal AGE levels (determined by Raman microspectroscopy at specific anatomical locations) and bone macroscopic and microscopic properties, as demonstrated by the biomechanical measures of crack growth and microindentation respectively. We found that in OVE26 mice, a transgenic model of severe early onset T1D, AGEs were increased by Raman (carboxymethyl-lysine [CML] wildtype (WT): 0.0143 ±0.0005 vs T1D: 0.0175 ±0.0002, p = 0.003) at the periosteal surface. These differences were associated with less tough bone in T1D by fracture mechanics (propagation toughness WT: 4.73 ± 0.32 vs T1D: 3.39 ± 0.24 NM/m1/2, p = 0.010) and by reference point indentation (indentation distance increase WT: 6.85 ± 0.44 vs T1D: 9.04 ± 0.77 μm; p = 0.043). Within T1D, higher AGEs by Raman correlated inversely with macroscopic bone toughness. These data add to the existing body of knowledge regarding AGEs and the relationship between skeletal AGEs with biomechanical indices.

Dietary Advanced Glycation End Products and Risk Factors for Chronic Disease: A Systematic Review of Randomised Controlled Trials.

Dietary advanced glycation end-products (AGEs) form during heating and processing of food products and are widely prevalent in the modern Western diet. Recent systematic reviews indicate that consumption of dietary AGEs may promote inflammation, oxidative stress and insulin resistance. Experimental evidence indicates that dietary AGEs may also induce renal damage, however, this outcome has not been considered in previous systematic reviews. The purpose of this review was to examine the effect of consumption of a high AGE diet on biomarkers of chronic disease, including chronic kidney disease (CKD), in human randomized controlled trials (RCTs). Six databases (SCOPUS, CINHAL, EMBASE, Medline, Biological abstracts and Web of Science) were searched for randomised controlled dietary trials that compared high AGE intake to low AGE intake in adults with and without obesity, diabetes or CKD. Twelve dietary AGE interventions were identified with a total of 293 participants. A high AGE diet increased circulating tumour necrosis factor-alpha and AGEs in all populations. A high AGE diet increased 8-isoprostanes in healthy adults, and vascular cell adhesion molecule-1 (VCAM-1) in patients with diabetes. Markers of CKD were not widely assessed. The evidence presented indicates that a high AGE diet may contribute to risk factors associated with chronic disease, such as inflammation and oxidative stress, however, due to a lack of high quality randomised trials, more research is required.

Abstract 11598: Increased Advanced Glycation End-Products Accelerate the Progress of Left Ventricular Hypertrophy Under Condition of Elevated Oxidative Stress or Insulin Resistance in Patients With Hypertension

Background: Elevated oxidative stress or insulin resistance has been shown to promote the production of advanced glycation end-products (AGEs) in patients with hypertension (HT). Because AGEs enhance left ventricular hypertrophy (LVH) via the activation of nuclear factor-kappa B, it is considered that increased AGEs contribute to LVH in HT patients. The aim of this study was to investigate the effect of increased AGEs on LVH in them. Methods: Eighty five HT patients aged 65 ± 9 years were prospectively followed up for a year, whose blood pressure was controlled under 140/90mmHg. We assessed patients’ glucose and lipid metabolism and neurohumoral factors including plasma noradrenaline and renin activity as clinical characteristics. We measured serum malondialdehyde-modified LDL-cholesterol (MDA-LDL) and plasma pentosidine as parameters of oxidative stress and AGEs, respectively. Homeostasis model assessment ratio (HOMA-R), estimate glomerular filtration rate (eGFR) and left ventricular mass index (LVMI) were assessed as parameters of insulin resistance, renal function and LVH, respectively. All parameters were assessed before and after one-year observation period. We examined the change in each parameter from baseline to the value measured after the observation period ([[Unable to Display Character: &amp;#8895;]]MDA-LDL, [[Unable to Display Character: &amp;#8895;]]pentosidine, [[Unable to Display Character: &amp;#8895;]]HOMA-R and [[Unable to Display Character: &amp;#8895;]]LVMI). We divided patients into two groups based on the median of baseline pentosidine: high AGEs and low AGEs groups. We compared baseline values between the two groups. We analyzed the relationships among [[Unable to Display Character: &amp;#8895;]]MDA-LDL, [[Unable to Display Character: &amp;#8895;]]HOMA-R, [[Unable to Display Character: &amp;#8895;]]Pentosidine and [[Unable to Display Character: &amp;#8895;]]LVMI, and performed stepwise multiple regression analysis using parameters of clinical characteristics and AGEs to detect the predictors for the LVH progress after one year. Results: Baseline LVMI was significantly higher in the high AGEs group than in the low AGEs group (P&lt;0.05). [[Unable to Display Character: &amp;#8895;]]Pentosidine was positively correlated with [[Unable to Display Character: &amp;#8895;]]MDA-LDL (r=0.34, P&lt;0.01),[[Unable to Display Character: &amp;#8895;]]HOMA-R (r=0.37, P&lt;0.01) and [[Unable to Display Character: &amp;#8895;]]LVMI (r=0.39, P&lt;0.05). Multiple regression analysis detected pentosidine as a significant independent predictor for the LVH progress (β=0.407, P=0.005) (R2=0.315). Conclusion: Increased AGEs accelerated the LVH progress under condition of elevated oxidative stress or insulin resistance in HT patients.

Dietary advanced glycation end-products, its pulmonary receptor, and high mobility group box 1 in aspiration lung injury

BackgroundGastric aspiration is a significant cause of acute lung injury and acute respiratory distress syndrome. Environmental risk factors, such as a diet high in proinflammatory advanced glycation end-products (AGEs), may render some patients more susceptible to lung injury after aspiration. We hypothesized that high dietary AGEs increase its pulmonary receptor, RAGE, producing an amplified pulmonary inflammatory response in the presence of high mobility group box 1 (HMGB1), a RAGE ligand and an endogenous signal of epithelial cell injury after aspiration. Materials and methodsCD-1 mice were fed either a low AGE or high AGE diet for 4 wk. After aspiration injury with acidified small gastric particles, bronchoalveolar lavage and whole-lung tissue samples were collected at 5 min, 1 h, 5 h, and 24 h after injury. RAGE, soluble RAGE (sRAGE), HMGB1, cytokine and chemokine concentrations, albumin levels, neutrophil influx, and lung myeloperoxidase activity were measured. ResultsWe observed that high AGE-fed mice exhibited greater pulmonary RAGE levels before aspiration and increased bronchoalveolar lavage sRAGE levels after aspiration compared with low AGE-fed mice. Lavage HMGB1 levels rose immediately after aspiration, peaking at 1 h, and strongly correlated with sRAGE levels in both dietary groups. High AGE-fed mice demonstrated higher cytokine and chemokine levels with increased pulmonary myeloperoxidase activity over 24 h versus low AGE-fed mice. ConclusionsThis study indicates that high dietary AGEs can increase pulmonary RAGE, augmenting the inflammatory response to aspiration in the presence of endogenous damage signals such as HMGB1.

Elimination of Middle-Sized Uremic Solutes with High-Flux and High-Cut-Off Membranes: A Randomized in vivo Study

The elimination of substances between 10 and 50 kDa by conventional high-flux membranes is not satisfactory. We investigated in vivo the elimination of middle-sized uremic solutes by conventional polyflux (PF) and modified high-cut-off (HCO) membranes. All 12 patients underwent four treatments, two with the HCO dialyzer and two with the PF dialyzer, each in either a haemodialysis (HD) or haemodiafiltration (HDF) mode. The reduction ratio of urea, creatinine, β₂-microglobulin (β₂M), leptin, soluble TNF-RI, complement factor D, IL-6, sIL-6 receptor, advanced glycation end-products (AGEs) and albumin was determined. In addition, the amount removed was determined in the dialysate for β₂M, complement factor D, AGEs and albumin. Treatment with HCO removed β₂M, sTNF-RI, factor D, and high molecular AGE significantly better than conventional high-flux membranes. The albumin loss was higher when using HCO membranes. HCO membranes are a promising approach to improve removal of uremic toxins not affected by conventional high-flux membranes.

Dietary glycotoxins exacerbate progression of experimental fatty liver disease

Advanced glycation end-products (AGEs) levels are high in western diets and contribute to tissue injury via activation of RAGE (receptor for AGEs) and generation of reactive oxygen species (ROS). Here, we determined if high dietary AGE intake worsens progression of non-alcoholic fatty liver disease (NAFLD). Male Sprague Dawley rats were fed a methionine choline deficient (MCD) diet for 6 weeks before 6 weeks of a high AGE MCD diet through baking. They were compared with animals on MCD diet or a methionine choline replete (MCR) diet alone for 12 weeks. Hepatic ROS, triglycerides, biochemistry, picro-sirius morphometry, hepatic mRNA expression and immunohistochemistry were determined. Primary hepatic stellate cells (HSCs) from both MCR and MCD animals were exposed to AGEs. ROS, proliferation and mRNA expression were determined. The high AGE MCD diet increased hepatic AGE content and elevated triglycerides, NADPH dependent superoxide production, HNE adducts, steatosis, steatohepatitis (CD43, IL-6, TNF-α) and fibrosis (α-SMA, CTGF, COL1A, picrosirius) compared to MCD alone. In HSCs, AGEs significantly increased ROS production, bromodeoxyuridine proliferation and MCP-1, IL-6, α-SMA, and RAGE expression in HSCs from MCD but not MCR animals. These effects were abrogated by RAGE or NADPH oxidase blockade. In the MCD model of NAFLD, high dietary AGEs increases hepatic AGE content and exacerbates liver injury, inflammation, and liver fibrosis via oxidative stress and RAGE dependent profibrotic effects of AGEs on activated HSCs. This suggests that pharmacological and dietary strategies targeting the AGE/RAGE pathway could slow the progression of NAFLD.