Advanced glycation end-products in sickle cell anaemia

Tissue accumulation of advanced glycation end-products (AGEs) has been implicated in the oxidant-induced vascular pathology of diabetes and other diseases. Because homozygous sickle cell anaemia (SCA) is a state of oxidative stress, we tested the hypothesis that circulating AGE levels are elevated in SCA. Blood was obtained from age- and race-matched children classified as either non-sickle cell controls, SCA without vaso-occlusive crisis (SCA - VOC), or SCA with vaso-occlusive crisis (SCA + VOC). Plasma and red blood cell (RBC) AGE levels were measured by immunoassay. RBC levels of reduced (GSH) and oxidized (GSSG) glutathione were measured by capillary electrophoresis as an indicator of endogenous antioxidant status. The results showed that plasma AGE levels and the rate of RBC AGE accumulation were significantly higher in patients with SCA compared with controls. GSH was not different between groups but was significantly inversely correlated with plasma AGEs in both controls and patients with SCA. GSSG was significantly lower and GSH/GSSG higher in SCA + VOC patients, suggesting that GSH/GSSG might be an objective indicator of acute VOC or a risk factor for VOC. We conclude that circulating AGE levels are strongly influenced by endogenous antioxidant status and may play a role in the vascular pathology of SCA.     

Elevated levels of serum advanced glycation end products in patients with non-alcoholic steatohepatitis

BACKGROUND AND AIM: Advanced glycation end products (AGE), senescent macroprotein derivatives formed at an accelerated rate in diabetes, play important roles in the pathogenesis of diabetic vascular complications. Recently, AGE have also been found to be involved in insulin resistance. Although non-alcoholic steatohepatitis (NASH) is generally considered a hepatic manifestation of insulin resistance, there are no reports showing the link of AGE to NASH. The aim of this study was to evaluate the clinical significance of AGE in patients with NASH. METHODS: Glyceraldehyde-derived AGE levels were assayed from serum obtained from 106 patients: 66 with NASH, 10 with simple steatosis, and 30 controls. RESULTS: Serum glyceraldehyde-derived AGE levels (U/mL) were significantly elevated in NASH patients (9.78 +/- 3.73) compared with simple steatosis (7.17 +/- 2.28, P = 0.018) or healthy controls (6.96 +/- 2.36, P = 0.003). Moreover, these were inversely correlated with adiponectin, an adipocytokine with insulin-sensitizing and anti-inflammatory properties. In addition, immunohistochemistry of glyceraldehyde-derived AGE showed intense staining in the livers of NASH patients. CONCLUSION: The present data suggest that the sustained increase of glyceraldehyde-derived AGE could at least in part contribute to the pathogenesis of NASH. The serum glyceraldehyde-derived AGE level may be a useful biomarker for discriminating NASH from simple steatosis.     

慢阻肺急性加重期患者血浆晚期糖基化终末产物和sRAGE研究

目的研究分析慢性阻塞性肺疾病(慢阻肺)患者血浆中晚期糖基化终末产物(AGEs)和可溶性糖基化终末产物受体(sRAGE)的水平及与慢阻肺患者肺功能的关系。方法选取河北省承德县医院收治的120例慢阻肺患者(慢阻肺组)、50例健康人群(对照组),分别检测两组的血浆AGEs、sRAGE及肺功能等指标。结果慢阻肺组患者的血浆中AGEs(36.25±2.98)ug/m L显著的高于对照组的(28.94±2.31)ug/m L,sRAGE为(338.41±194.26)pg/m L显著的低于对照组的(871.50±226.49)pg/m L且差异均具有统计学意义(P0.05)。慢阻肺组患者血浆AGEs与患者的FEV1%呈显著的负相关关系(r=-0.594,P=0.0000.001);慢阻肺组患者血浆sRAGE与患者的FEV1%呈显著的正相关关系(r=0.552,P=0.0000.001)。结论慢阻肺患者血浆中AGEs、sRAGE水平发生显著的改变,AGEs与患者的肺功能呈负相关性、sRAGE与患者的肺功能呈正相关关系。     

Serum levels of low molecular weight advanced glycation end products in diabetic subjects

AIMS: One of the principal theories of the development of diabetic complications proposes that increased levels of advanced glycation end products (AGE) are formed in diabetes by prolonged exposure of proteins, lipids and nucleotides to glucose. Such AGEs may contribute to the development of diabetic complications by a number of mechanisms. Circulating AGEs can be detected in serum, and in the present study, we analysed the clinical correlates of circulating serum low molecular weight AGE (LMW-AGE). METHODS: Serum LMW-AGE was measured in 106 non-diabetic and 499 diabetic subjects using fluorescence spectroscopy. Results were calibrated against an in-house AGE albumin preparation, and expressed as absolute fluorescence units (AFU). RESULTS: Serum LMW-AGE values were significantly higher in diabetic than non-diabetic subjects [median 7.5 (range 0-595.5) vs. 5.3 (1.0-15.5) AFU, P<0.01]. In the normal subjects, there were significant correlations between serum LMW-AGE and age (r=0.42, P<0.01) and serum creatinine (r=0.39, P<0.01). In the diabetic patients, serum LMW-AGE correlated significantly with age (r=0.315, P<0.01), systolic blood pressure (r=0.141, P=0.002), serum creatinine (r=0.449, P<0.01) and urinary albumin/creatinine ratio (ACR) (r=0.265, P<0.01). There was no correlation between serum LMW-AGE and HbA1c. On regression analysis, with serum LMW-AGE as the dependent variable, serum creatinine emerged as the most significant factor (t=8.1, P<0.01), followed by age (t=4.0, P<0.01) and ACR (t=2.9, P=0.004). There was no significant difference in serum LMW-AGE between those with and without retinopathy or in those with vascular disease. CONCLUSIONS: We conclude that circulating LMW-AGEs are increased in diabetic subjects. The major determinant appears to be renal dysfunction in the form of raised albumin/creatinine ratio or creatinine. There was no association with other markers of vascular disease or presence of diabetic complications.     

Association between serum levels of soluble receptor for advanced glycation end products and circulating advanced glycation end products in type 2 diabetes

Aims/hypothesis Activation of the receptor for advanced glycation end products (RAGE, also known as AGE-specific receptor [AGER]) has been implicated in the development of diabetic vascular complications. Blockade of RAGE using a soluble form of the receptor (sRAGE) suppressed vascular hyperpermeability and atherosclerosis in animal models. Since little is known about the regulation of endogenous sRAGE levels, we determined whether serum sRAGE is influenced by circulating AGEs and the severity of nephropathy in type 2 diabetic patients.Materials and methods We recruited 150 healthy control and 318 diabetic subjects. Diabetic subjects were subdivided into those with proteinuria, microalbuminuria or normoalbuminuria. Serum sRAGE was assayed by ELISA and serum AGEs by competitive ELISA using a polyclonal rabbit antiserum raised against AGE-RNase.Results Diabetic subjects had higher sRAGE (1,029.5 pg/ml [766.1–1,423.0] interquartile range vs 1,002.6 [726.5–1,345.3], p<0.05) and AGEs (4.07±1.13, SD, unit/ml vs 3.39±1.05, p<0.01) than controls. Proteinuric subjects had the highest sRAGE levels and there was a significant trend between the severity of nephropathy and sRAGE (p=0.01). In diabetic subjects, serum log(sRAGE) correlated with AGEs (r=0.27, p<0.001), log(plasma creatinine) (r=0.31, p<0.001), log(urine AER) (r=0.24, p<0.01) and log(triglycerides) (r=0.15, p<0.01). On stepwise linear regression analysis, AGEs and creatinine levels were the main independent determinants of sRAGE concentration.Conclusions/interpretation Serum sRAGE levels and circulating AGEs are associated with the severity of nephropathy in type 2 diabetic patients. Prospective studies are required to determine whether endogenous sRAGE potentially influences the development of diabetic vascular complications.     

Correlation between serum advanced glycation end products and dietary intake of advanced glycation end products estimated from home cooking and food frequency questionnaires

Background & aimsTo our knowledge the association between dietary advanced glycation end-products (dAGEs) and cardiometabolic disease is limited. Our aim was to examine the association between dAGEs and serum concentration of carboxymethyl-lysine (CML) or soluble receptor advanced glycation end-products (sRAGEs), and to assess the difference on dAGEs and circulating AGEs according to lifestyle and biochemical measures.Methods and results52 overweight or obese adults diagnosed with type 2 diabetes were included in this cross-sectional analysis. dAGEs were estimated from a Food Frequency Questionnaire (FFQ) or from a FFQ + Home Cooking Frequency Questionnaire (HCFQ). Serum concentrations of CML and sRAGEs were measured by ELISA. Correlation tests were used to analyze the association between dAGEs derived from the FFQ or FFQ + HCFQ and concentrations of CML or sRAGEs. Demographic characteristics, lifestyle factors and biochemical measures were analyzed according to sRAGEs and dAGEs using student t-test and ANCOVA.A significant inverse association was found between serum sRAGEs and dAGEs estimated using the FFQ + HCFQ (r = −0.36, p = 0.010), whereas no association was found for dAGEs derived from the FFQ alone. No association was observed between CML and dAGEs. dAGEs intake estimated from the FFQ + HCFQ was significantly higher among younger and male participants, and in those with higher BMI, higher Hb1Ac levels, longer time with type 2 diabetes, lower adherence to Mediterranean diet, and higher use of culinary techniques that generate more AGEs (all p values p < 0.05).ConclusionsThese results show knowledge on culinary techniques is relevant to derive the association between dAGEs intake and cardiometabolic risk factors.     

Controlling the receptor for advanced glycation end‐products to conquer diabetic vascular complications

Diabetic vascular complications, such as cardiovascular disease, stroke and microangiopathy, lead to high rates of morbidity and mortality in patients with long‐term diabetes. Extensive intracellular and extracellular formation of advanced glycation end‐products (AGE) is considered a causative factor in vascular injuries in diabetes. Receptor‐dependent mechanisms are involved in AGE‐induced cellular dysfunction and tissue damage. The receptor for AGE (RAGE), originally an AGE‐binding receptor, is now recognized as a member of pattern‐recognition receptors and a pro‐inflammatory molecular device that mediates danger signals to the body. Previous animal studies have shown RAGE dependent of diabetic vascular injuries. Prophylactic and therapeutic strategies focusing on RAGE and its ligand axis will be of great importance in conquering diabetic vascular complications. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00191.x, 2012)     

内源分泌型晚期糖基化终末产物受体与糖尿病周围神经病变的相关性

目的 探讨2型糖尿病患者周围神经病变(DPN)与内源分泌型晚期糖基化终末产物受体(esRAGE)的关系.方法 收集2008年6月至2009年3月于福建医科大学第二医院内分泌科住院的2型糖尿病患者61例及门诊体检的健康志愿者24名,根据有无合并糖尿病周围神经病变将糖尿病患者分2组,DPN组62例,无DPN组19例.采用酶联免疫吸附法(ELISA)测定血浆esRAGE水平.应用肌电诱发电位仪进行神经功能检查.测定受试者血压、体重指数、空腹血糖、糖化血红蛋白(HbA1c)、血脂.采用student t检验和非参数Mann-Whitney U检验分析两组问数据,利用Logistic回归分析糖尿病周围神经病变的相关因素.结果 正常对照组和2型糖尿病组患者血浆esRAGE水平无明显差别[(0.28±0.13)μg/L和(0.25±0.15)μg/L,P＞0.05],但在2型糖尿病患者中合并DPN组和无合并DPN组之间血浆esRAGE水平差别有显著性意义[(0.21±0.14)μg/L和(0.33±0.13)μg/L,P＜0.01],两组之间的年龄和糖化血红蛋白(HbA1c)也存在差别,Logistic回归分析提示年龄、HbA1c、血浆esRAGE水平与糖尿病周围神经病变相关,esRAGE是糖尿病周围神经病变保护因素(OR=0.001,P＜0.05).结论 2型糖尿病患者血浆esRAGE水平和正常人无明显差别.esRAGE是2型糖尿病周围神经病变的保护因素,而年龄和HbAlc是其危险因素.     

Low levels of soluble receptor for advanced glycation end products in non-ST elevation myocardial infarction patients

BACKGROUND:

Interaction of the receptors for advanced glycation end products (RAGEs) with advanced glycation end products (AGEs) results in expression of inflammatory mediators (tumor necrosis factor-alpha [TNF-α] and soluble vascular cell adhesion molecule-1 [sVCAM-1]), activation of nuclear factor-kappa B and induction of oxidative stress – all of which have been implicated in atherosclerosis. Soluble RAGE (sRAGE) acts as a decoy for the RAGE ligand and is protective against atherosclerosis.

OBJECTIVES:

To determine whether levels of serum sRAGE are lower, and whether levels of serum AGEs, TNF-α and sVCAM-1 are higher in non-ST elevation myocardial infarction (NSTEMI) patients than in healthy control subjects; and whether sRAGE or the ratio of AGEs to sRAGE (AGEs/sRAGE) is a predictor/biomarker of NSTEMI.

METHODS:

Serum levels of sRAGE, AGEs, TNF-α and sVCAM-1 were measured in 46 men with NSTEMI and 28 age- and sex-matched control subjects. Angiography was performed in the NSTEMI patients.

RESULTS:

sRAGE levels were lower, and levels of AGEs, TNF-α, sVCAM-1 and AGEs/sRAGE were higher in NSTEMI patients than in control subjects. sRAGE levels were negatively correlated with the number of diseased coronary vessels, serum AGEs, AGEs/sRAGE, TNF-α and sVCAM-1. The sensitivity of the AGEs/sRAGE test is greater than that of the sRAGE test, while the specificity and predictive values of the sRAGE test are greater than those of the AGEs/sRAGE test for identifying NSTEMI patients.

CONCLUSIONS:

Serum levels of sRAGE were low in NSTEMI patients, and were negatively correlated with extent of lesion, inflammatory mediators, AGEs and AGEs/sRAGE. Both sRAGE and AGEs/sRAGE may serve as biomarkers/predictors for identifying NSTEMI patients.     

冠心病并代谢综合征患者血清糖基化终末产物的水平及其临床意义

目的:研究冠心病并代谢综合征(MS)患者血清糖基化终末产物(AGE)含量的变化及其临床意义。方法:选择单纯MS患者(A组)32例,单纯冠心病患者(B组)36例,冠心病并MS患者(C组)39例和正常对照(D组)28例。对所有受试者测量其身高、体重、腰围(WC)、臀围(HC);测血脂、空腹血糖(FBG)、胰岛素(FIN)、AGE;计算体质指数(BMI)、腰臀比(WHR)、胰岛素抵抗指数(HOMA-IR)并进行比较。结果:A、B、C组患者的FIN、HOMA-IR、AGE均高于D组,C组的HOMA-IR、AGE分别高于A、B组。直线相关分析显示,HOMA-IR与BMI、WC、TG、FBG、FIN和AGE呈正相关,与HDL呈负相关。结论:冠心病并MS患者AGE的表达异常升高。     

糖基化终末产物与肝病

肝脏是糖基化终末产物的主要代谢部位,肝病时伴随的氧化应激、糖耐量损害以及肝肾功能降低导致糖基化终末产物增加,而糖基化终末产物可通过促进氧应激/脂质过氧化、炎症反应以及纤维化等途径,加重肝脏损伤。     

Differential accumulation of advanced glycation end products in the course of diabetic retinopathy

Aims/hypothesis. Glycated proteins, formed by reaction of glucose and protein, react further yielding numerous, mostly undefined advanced glycation end products (AGE). The recently characterized imidazolone-type AGE (AG-1) is non-oxidatively formed involving 3-deoxyglucosone whereas some AGEs, particularly Nɛ-(carboxymethyl)lysine (CML), are formed only in the presence of oxygen. Methods. To study the possible contribution of oxidative and non-oxidative AGE formation in the development of diabetic retinopathy antibodies directed against CML-type and imidazolone-type AGEs were characterized by dot blot analysis and used to localize these well-characterized epitops in the retinas from diabetic rats (early course) and from human Type I (insulin-dependent) diabetes mellitus with laser-treated proliferative diabetic retinopathy (late course). Results. In non-diabetic rats CML was moderately positive in neuroglial and vascular structures of non-diabetic rat retinas and increased strongly in diabetic retinas. Anti-imidiazolone antibody staining was strongly positive only in diabetic capillaries. Advanced human diabetic retinopathy showed strong CML-immunolabelling of the entire retina whereas control samples showed moderate staining of neuroglial structures only with the polyclonal CML-antibody. Anti-imidiazolone antibody staining was faint in the inner retina of control sections but were strong throughout the entire diabetic retina. Immunolabelling for the AGE-receptor was congruent with a marker of Müller cells. Conclusion/interpretation. Our data indicate that the oxidatively formed CML is present in non-diabetic retinas as a regular constituent but increases in diabetes both in neuroglial and vascular components. Imidazolone-type AGE are restricted to microvessels and spread during later stages over the entire retina, co-localizing with the expression of AGE-receptor. [Diabetologia (1999) 42: 728–736] Received: 22 October 1998 and in revised form: 11 January 1999     

Increased serum concentrations of advanced glycation end products: a marker of coronary artery disease activity in type 2 diabetic patients

OBJECTIVE—To assess whether the concentrations of serum advanced glycation end products (AGE) in diabetic patients with obstructive coronary artery disease differ from those in type 2 diabetic patients without obstructive coronary artery disease.
DESIGN—Serum AGE concentrations were measured in type 2 diabetic patients and in non-diabetic patients, both with and without obstructive coronary artery disease, and the relation between these values and coronary disease severity was evaluated.
RESULTS—Mean (SD) serum AGE concentrations were higher (p < 0.0125) in type 2 diabetic patients with obstructive coronary artery disease (5.5 (2.5) mU/ml, n = 30) than in patients without obstructive coronary artery disease (2.8 (0.5) mU/ml, n = 12), and higher than in non-diabetic patients with (3.4 (1.0) mU/ml, n = 28) and without (3.2 (0.4) mU/ml, n = 13) obstructive coronary artery disease. Serum AGE was associated with the degree of coronary arteriosclerosis in type 2 diabetic patients with obstructive coronary artery disease (single vessel: n = 13, 3.4 (0.9) mU/m; two vessel: n = 6, 5.7 (1.6) mU/m; three vessel: n = 11, 7.2 (2.5) mU/ml). Serum AGE was positively correlated with serum mean four year HbA_1C (r = 0.46, p < 0.01), but not with recent serum HbA_1C (r = 0.24). The four groups did not differ in the other coronary risk factors.
CONCLUSIONS—Serum AGE concentrations may be associated with long term poor glycaemic control and reflect the severity of coronary arteriosclerosis in type 2 diabetic patients.


Keywords: advanced glycation end products; non-insulin dependent diabetes; coronary artery disease