酶联免疫吸附分析方法(ELISA)检测血浆中糖基化终极产物

目的建立竞争性ELISA方法，测定血液中的高级糖化终产物的含量。方法对兔及牛血浆白蛋白进行体外葡萄糖修饰，得到糖基化终极产物抗原；用兔此抗原免疫新西兰大白兔得到与其特异结合的抗体。结果1．经过TNBS方法及聚丙稀凝胶电泳鉴定修饰抗原，发现修饰前后蛋白携带自由氨基数至少35％已被葡萄糖修饰且分子量也发生变化。2．免疫获得抗糖基化终极产物的多克隆抗体，并鉴定了此多抗只抗葡萄糖修饰的蛋白而不抗载体蛋白。3．用葡萄糖修饰的蛋白及其多克隆抗体制成ELISA试剂盒，批间、批内变异系数分别为5．8％和9．8％，灵敏度为0．5u／ml。结论得到检测血浆糖基化终极产物的ELISA试剂盒。     

晚期糖基化终末产物致动脉粥样硬化的机制

晚期糖基化终末产物(advanced glycation end products,AGE)是由还原糖的羰基与游离氨基反应形成的复合物.AGE通过与其受体(RAGE)结合,改变细胞内信号转导、诱导炎症、增强氧化应激;与胶原交联、修饰脂蛋白等损害血管的完整性;这些导致血管内皮细胞功能紊乱,刺激平滑肌细胞迁移增殖,启动及加速糖尿病动脉粥样硬化和血管并发症的发生发展.阻断AGE-RAGE系统对防治糖尿病并发症具有重要意义.     

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.     

Role of advanced glycation end products in cardiovascular disease

Advanced glycation end products(AGEs) are produced through the non enzymatic glycation and oxidation of proteins,lipids and nucleic acids.Enhanced formation of AGEs occurs particularly in conditions associated with hyperglycaemia such as diabetes mellitus(DM).AGEs are believed to have a key role in the development and progression of cardiovascular disease in patients with DM through the modif ication of the structure,function and mechanical properties of tissues through crosslinking intracellular as well as extracellular matrix proteins and through modulating cellular processes through binding to cell surface receptors [receptor for AGEs(RAGE)].A number of studies have shown a correlation between serum AGE levels and the development and severity of heart failure(HF).Moreover,some studies have suggested that therapies targeted against AGEs may have therapeutic potential in patients with HF.The purpose of this review is to discuss the role of AGEs in cardiovascular disease and in particular in heart failure,focussing on both cellular mechanisms of action as well as highlighting how targeting AGEs may represent a novel therapeutic strategy in the treatment of HF.     

Differential expression of receptors for advanced glycation end products on monocytes in patients with IDDM

Summary Accelerated modification of proteins by glucose terminating in the formation of advanced glycation endproducts (AGEs) is one of the main pathogenetic mechanisms of diabetes-associated complications. One pathway by which AGEs may exert their effects is by interaction with specific receptors initially identified on macrophages, monocytes and endothelial cells. As AGE-induced autocrine upregulation of AGE receptors has been observed in vitro, we hypothesized that AGE-binding might be enhanced in diabetic patients to compensate for the elevated levels of circulating AGEs. We therefore examined the expression of AGE-binding sites on peripheral monocytes, serum levels of AGEs and AGE-induced cytokine production in patients with insulin-dependent diabetes mellitus (IDDM) compared to age-matched, healthy control subjects. In patients, AGE-binding capacity was significantly increased and there was only one class of binding sites, as revealed by Scatchard analysis (1.8 × 10⁵ vs 1.4 × 10⁵ binding sites per cell). Affinity of binding was, however, similar (K_a 1.5 × 10⁶ vs 1.4 × 10⁶ mol^{− 1}). Saturation of binding was reached at 2.0–3.0 μmol/l with AGE-bovine serum albumin (BSA) as ligand. In contrast, cytometry using fluorescein isothiocyanate-labelled AGE-proteins showed no saturability and reversibility of AGE-binding up to 80 μmol/l, indicating non-specific binding in this concentration range. Again, this non-specific binding was significantly higher in IDDM patients. In addition, we found much higher levels of circulating AGEs in patients as compared to controls and studied possible functional consequences of increased AGE binding in vitro, monocyte stimulation by AGEs triggering cytokine release to a similar extent in patients and controls, i. e. independently of the AGE-binding capacity. Our finding of an enhanced overall AGE-binding capacity of peripheral monocytes in IDDM could be instrumental in limiting the plasma concentration of AGEs, the non-specific binding coming into play after saturation of specific binding sites by higher plasma AGE-levels. Both binding strategies may act in concert as “damage limitation mechanisms” in the development of AGE-dependent diabetic complications. [Diabetologia (1998) 41: 674–680] Received: 30 September 1997 and in revised form: 15 January 1998     

肝素对血液透析病人单核细胞表面晚期糖基化终产物受体的影响

目的 研究肝素对慢性肾衰竭长期血液透析（血透）病人单核细胞表面晚期糖基化终产物（AGE）受体的影响。探讨血透病人体内AGE潴留的机制。方法 用核素[^125I]标记AGE修饰的人血清白蛋白（AGE-HSA）。用密度梯度离心法分离人外周血单核细胞,用放射性配体-受体结合法观察肝素和低分子量肝素对血透病人及正常人单核细胞表面AGE受体的影响。结果 采学常规持续肝素输注法进行抗凝的血透病人,在透析后15min,单核细胞与^125I-AGE-HSA的结合被抑制27%,作用持续6h,透析后24h结合率恢复至透析前水平用低分子量肝素抗凝的病人,透析中及透析后单核细胞与^125I-AGE-HSA的结合无明显变化。体外实验显示,肝素抑制AGE与其单核细胞表面AGE受体的结合。这种作用呈剂量依赖性;低分子量肝素对AGE受体不具有封闭作用。结论 肝素可以阻断AGE与其单核细胞表达AGE受体的结合,从而干扰体内AGE的清除,可能是造成血透病人体内AGE潴的原因之一。     

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.     

Advanced glycation end products and advanced oxidation protein products in hemodialyzed patients

Chronic renal failure is associated with increased oxidative and carbonyl stresses that contribute to long-term uremic complications. In our study, we determined two markers of these stresses--AGEs (advanced glycation end products) and AOPP (advanced oxidation protein products)--in chronic hemodialysis patients in order to find out their relationship to the dialysis treatment. Plasmas of 20 hemodialyzed patients treated with modified cellulose membranes were examined at 0 and 15 min and at the end (i.e. after 4 h) of the dialysis session. AGEs were estimated using a spectrofluorometric method (excitation 350 nm, emission 440 nm) and are expressed in AU (arbitrary units)/g protein. AOPP were determined spectrophotometrically (absorbance at 340 nm) and are expressed in chloramine units per gram of protein (micromol/g). AOPP decrease slightly from 0 to 15 min of the dialysis procedure (4.0 +/- 1.5 vs. 3.0 +/- 0.9 micromol/g, p < 0.01). However, they are increased at the end of the session (5.0 +/- 2.1 micromol/l vs. 15 min, p < 0.01, not significant vs. beginning). On the other hand, AGEs decrease continuously from the beginning to the end of the session (mainly in the first minutes of the dialysis) (1.52 +/- 0.34 x 10(4) AU/g at 0 min, 1.39 +/- 0.33 x 10(4) AU/g at 15 min, p < 0.001 vs. beginning, 1.30 +/- 0.33 x 10(4) AU/g at the end, p < 0.001 vs. beginning, not significant vs. 15 min). Neither AGEs nor AOPP correlate with the age of hemodialyzed patients and with the number of years of the dialysis treatment. AOPP correlate with AGEs before the dialysis session (r = 0.62, p < 0.05) but not after the session (r = 0.29, not significant). According to our results, AGEs may serve more as a marker of chronic damage while AOPP may better describe acute oxidative stress during the dialysis treatment.     

Positive association between serum levels of advanced glycation end products and the soluble form of receptor for advanced glycation end products in nondiabetic subjects

The advanced glycation end products (AGEs)-receptor for AGE (RAGE) axis is implicated in diabetic vascular complications. Administration of soluble form of RAGE (sRAGE) to mice has been shown to block the AGE-elicited tissue damage by acting as a decoy. These observations suggest that endogenous sRAGE may capture and eliminate circulating AGEs and decrease its serum levels. However, because AGEs up-regulate tissue RAGE expression and endogenous sRAGE could be generated from the cleavage of cell surface RAGE, sRAGE may be positively, rather than inversely, associated with circulating AGEs by reflecting tissue RAGE expression. In this study, we investigated the association of sRAGE with serum levels of AGEs in humans. Data for fasting serum sRAGE and AGE levels of 184 nondiabetic subjects were obtained from a general population in Japan. We also measured body mass index (BMI), waist circumference, blood pressure, and blood biochemistries in this population. Uni- and multivariate analyses were applied for the determinants of serum sRAGE levels. The average sRAGE levels were 0.40 +/- 0.17 ng/mL in males and 0.43 +/- 0.14 ng/mL in females, respectively. In the univariate analysis, BMI (P < .05, inversely), waist circumference (P < .05, inversely), AGEs (P < .05), and alcohol intake (P < .05, inversely) were significantly associated with sRAGE levels. After performing multivariate analyses, BMI (P < .05, inversely) and AGEs (P < .05) still remained significant independently. The present study is the first demonstration that serum sRAGE levels were positively associated with circulating AGEs in the nondiabetic general population. Endogenous sRAGE levels are elevated in parallel with serum AGE levels.     

糖基化终产物对内皮细胞过氧化物酶体增生物活化受体表达的影响

目的 探讨糖基化终产物(AGEs)对内皮细胞过氧化物酶体增生物活化受体(PPAR)表达的影响。方法 以体外培养的人内皮细胞系(ECV)-304为研究对象，应用RT-PCR、Western印迹方法观察不同浓度AGEs对内皮细胞PPARa、PPAR7表达的影响。结果 ECV-304有PPAR7、PPARa的基础表达，AGEs可使PPAR7的mRNA及蛋白表达上调。结论 AGEs对PPAR表达具有上调作用，可能参与糖尿病致动脉粥样硬化的病理过程。     

Serum levels of advanced glycation end products and their receptors sRAGE and Galectin-3 in chronic pancreatitis

Background/Objectives: AGE and their receptors like RAGE and Galectin-3 can activate inflammatory pathways and have been associated with chronic inflammatory diseases. Several studies investigated the role of AGE, Galectin-3 and sRAGE in pancreatic diseases, whereas no comprehensive data for chronic pancreatitis (CP) are available.MethodsSerum samples from CP patients without an active inflammatory process (85 ACP; 26 NACP patients) and 40 healthy controls were collected. Levels of AGE, sRAGE and Galectin-3 were measured by ELISA. To exclude potential influences of previously described RAGE SNPs on detected serum levels, we analyzed variants rs207128, rs207060, rs1800625, and rs1800624 by melting curve technique in 378 CP patients and 338 controls.ResultsAGE and Galectin-3 serum levels were significantly elevated in both ACP and NACP patients compared to controls (AGE: 56.61 ± 3.043 vs. 31.71 ± 2.308 ng/mL; p < 0.001; Galectin-3: 16.63 ± 0.6297 vs. 10.81 ± 0.4835 ng/mL; p < 0.001). In contrast, mean serum sRAGE levels were significantly reduced in CP patients compared to controls (sRAGE: 829.7 ± 37.10 vs. 1135 ± 55.74 ng/mL; p < 0.001). All results were consistent after correction for gender, age and diabetes mellitus. No genetic association with CP was found.ConclusionsOur extensive analysis demonstrated the importance of aging related pathways in the pathogenesis of CP. As the results were consistent in ACP and NACP, both entities most likely share common pathomechanisms. Most probably the involved pathways are a general hallmark of an inflammatory state in CP that is even present in symptom-free intervals.     

晚期糖基化终末产物受体在心血管疾病中的研究进展

晚期糖基化终末产物受体(RAGE)属于细胞表面免疫球蛋白超家族中的一员,广泛表达于人体内皮细胞、平滑肌细胞、系膜细胞、心肌细胞、单核巨噬细胞和神经元细胞等。RAGE不仅参与炎症反应,还与糖尿病慢性并发症的发生、发展,类风湿性关节炎,肿瘤的侵袭和转移,阿尔茨海默病,慢性肾病等有关。现主要论述其在心血管疾病中的作用。     

高级糖基化终末产物的合成及其与疾病的关系

高级糖基化终末产物(advanced glycation end products,AGEs)是由蛋白或者脂质暴露于还原糖中而形成的一组复杂且具有异质性的物质.该物质可通过内源性或外源性途径形成,大体可分为6种.AGEs可在不同种类的细胞内累积,影响细胞内及细胞外的结构和功能,同时它还可以通过和细胞表面的受体作用,通过信号传导,引发一系列的病理生理过程.AGEs沉积在细胞内,影响细胞功能,导致糖尿病血管并发症的发生.AGEs还与各种肿瘤的生物学特性相关,它可以修饰热休克蛋白27或者与AGEs受体相结合来影响肿瘤细胞的生长和浸润.AGEs的抑制物,如OPB-9195,可抑制这一系列病理生理过程.     

Hepatic disposal of advanced glycation end products during maturation and aging

Aging is characterized by progressive loss of metabolic and biochemical functions and accumulation of metabolic by-products, including advanced glycation end products (AGEs), which are observed in several pathological conditions. A number of waste macromolecules, including AGEs are taken up from the circulation by endocytosis mainly into liver sinusoidal endothelial cells (LSECs) and Kupffer cells (KCs). However, AGEs still accumulate in different tissues with aging, despite the presence of this clearance mechanism. The aim of the present study was to determine whether the efficiency of LSECs and KCs for disposal of AGEs changes through aging.