The role of advanced glycation end products (AGEs) in cardiovascular diseases is a matter of interest in the last years and the strong association between the action of AGEs on their receptor (RAGE) and atherosclerosis has attracted increased attention. The aim of this chapter is to review the results of our laboratory and others on the molecular mechanisms triggered by AGEs in the endothelium that could participate in the atherosclerotic process. These mechanisms and molecular pathways could be the source of new therapeutic targets against atherosclerosis or vascular disease. Oxidative stress in endothelium induced by AGEs triggers molecular signaling pathways that produce an inflammatory response or even endothelial dysfunction. Adhesion molecules expression at the membranes of endothelial cells as a consequence of this response or induced by other mechanisms involving AGEs mediates the adhesion of leukocytes to endothelium. This adhesion is a key step in the atherogenesis process and the possible involvement of AGE-RAGE axis in this process should be considered as a potential therapeutic target. Finally, potential pharmacological modulation of AGE-RAGE axis activity at the endothelium is suggested, but the specific pharmacological tools available nowadays are missing; respectively, drugs used for the treatment of cardiovascular and metabolic diseases could be helpful for AGE-RAGE axis modulation, thus also affecting endothelial (dys)function.
- advanced glycation end products
- endothelial dysfunction
- oxidative stress
- receptor for advanced glycation end products
- vascular adhesion molecules
- vascular inflammation
Cardiovascular diseases resulting from atherosclerosis have become the most important cause of mortality and morbidity in the general population . Although atherosclerosis develops as a consequence of multiple risk factors such as hypertension, dyslipidemia, diabetes, aging and smoking, the common pathway for its development is endothelial dysfunction and vascular inflammation . In the last two decades, the role of advanced glycation end products (AGEs) in the development of endothelial dysfunction has gained increasing interest [3, 4, 5], initially as a possible molecular mechanism of diabetic cardiovascular complications , and, in the last years, as an independent risk factor of vascular injury .
AGEs are products of non-enzymatic molecular modifications of proteins and lipids that affect the structure and function of the target molecule. They are produced endogenously by spontaneous reactions, but pathophysiological conditions may accelerate their formation and they also contribute to disease by different mechanisms.
AGEs comprise a heterogeneous group: the most studied are pentosidine and Nε-carboxymethyl-lysine (CML) and quantitatively, the most important in the tissues are the hydroimidazolones like CML . AGEs are formed by a combination of glycation, oxidation, and/or carbonylation reactions both in the extra- and in the intracellular space. Other processes involving lipid peroxidations in the cell membranes lead to the formation of advanced lipid end products, as for example, malondialdehyde . The classical mechanism of AGE formation is the slow Maillard reaction between glucose or reducing sugars and proteins . The interaction between the carbonyl groups of reducing sugars and amino groups of proteins results in the formation of a Schiff base within a few hours. Intramolecular rearrangement of the Schiff base results in more stable Amadori products . An example of these types of products is glycated hemoglobin or glycated albumin, the former is widely used in clinical practice for diagnosis and follow-up of diabetes mellitus and the last could be regarded as a smart alternative to modified hemoglobin for the same purposes, with less dependence on hematological diseases and intracellular conditions. Finally, the process of oxidation of the Amadori products leads to reactive carbonyl compounds and subsequently to the formation of AGEs within weeks to months. AGEs can also be formed intracellularly. Glucose is altered into reactive carbonyl compounds during glycolysis pathway, of which the best-known is methylglyoxal. The chemical reaction between these carbonyl compounds and proteins can result in AGEs .
Absorption of exogenous AGEs also contributes to their accumulation in tissues. Tobacco smoke contains highly reactive glycation products which rapidly form AGEs
The role of AGEs in cardiovascular diseases is a matter of interest in the last years , and the strong association between the axis of action of AGEs and their receptor (RAGE) and atherosclerosis or cardiovascular ischemic disease [3, 16, 17] has attracted increased attention. The aim of this chapter is to review the results of our laboratory and others on the molecular mechanisms triggered by AGEs in the endothelium that could participate in the atherosclerotic process. These mechanisms and molecular pathways could help in the development of new therapeutic targets against atherosclerosis or vascular disease.
2. Molecular mechanisms triggered by AGEs in the endothelium
It is generally accepted that AGEs target cells by three main mechanisms. First, proteins modified by AGEs have altered biological function, either enzymatic activity, binding properties or structural conformation. Second, extracellular matrix components modified by AGEs interact abnormally with other matrix components and with matrix receptors, such as integrins. This includes also the formation of new links or the alteration of those previously existing, between proteins, which may alter the physical properties of extracellular matrix and cell environment. Third, plasma proteins modified by AGEs bind to cell surface receptors, of which the receptor for AGEs (RAGE) is acknowledged to be the most important, activating intracellular signaling pathways and various cellular responses.
Binding of AGEs to RAGE is responsible for the generation of reactive oxygen species (ROS) and the activation of transcription factors such as nuclear factor-κB (NF-κB), with subsequent changes in the expression of many genes involved in vascular inflammation and endothelial dysfunction [18, 19, 20]. Besides from the involvement of AGEs-RAGE axis, the precursors of AGEs, like Amadori products or early glycated products also have a role in the global response of non-enzymatic glycation of proteins, so we will also discuss their effects on endothelial cells.
2.1. AGEs-induced ROS production in the endothelium
One of the first and best studied actions of AGEs on endothelial cells is the induction of ROS. The suggested mechanisms for this action are several and range from the activation of ROS-producing enzymes to the reduction of ROS-neutralizing enzymes. In the first group of enzymes or enzyme complexes are nicotinamide adenine dinucleotide phosphate (NADPH) oxidase  and mitochondria , whereas in the second, there are endothelial nitric oxide (NO) synthase (eNOS) , superoxide dismutase (SOD) and glutathione peroxidase [24, 25]. The molecular mechanisms of these actions have been related to the activation of NF-κB via RAGE [26, 27].
ROS production in endothelial cells has important consequences on endothelial activation. In brain microvascular endothelial cells, AGEs-induced ROS production enhances vascular endothelial growth factor (VEGF) expression, which mediates an increase in cell permeability , and platelet tissue factor up-regulation . Other mechanisms of AGEs on endothelial cells promoting endothelial activation or dysfunction are the generation of asymmetric dimethylarginine (ADMA, a metabolic by-product of natural protein modification processes in the cytoplasm of cells, that acts as a competitive inhibitor of NOS) , or impaired calcium signaling .
It is important to note that the effects of AGEs’ precursors (i.e. Amadori products or glycated proteins) on endothelial cells, differ from the effects of AGEs themselves. Several works have focused on this issue (see, for a review, ). Amadori products modify eNOS activity and gene expression, promoting apoptosis of endothelial cells [33, 34]. A recent study performed by our group has highlighted the important molecular and functional differences between early glycated human serum albumin (gHSA) and advanced glycated albumin (AGE-HSA), obtained commercially or by glucose incubation during 4 weeks at 37°C in aseptic conditions, respectively . The respective control molecules of these treatments were unmodified commercial HSA and HSA incubated for the same time than AGE-HSA, but without glucose (Ct-HSA). Molecular characterization of the early and advanced glycation products formed on each modified albumin (gHSA and AGE-HSA) were studied by matrix assisted laser desorption/ionization—time of flight (MALDI-TOF)-mass spectrometry. Once characterized, the effects on ROS production of human umbilical vein endothelial cells (HUVECs) under the stimuli of gHSA or AGE-HSA were compared . Low concentrations of gHSA enhanced long-lasting ROS production in HUVECs, whereas AGE-HSA induced extracellular ROS production after short time of incubation and at lower concentrations than gHSA. Extracellular ROS production of HUVEC was measured by the cytochrome C reduction method, whereas intracellular ROS production of HUVEC was measured by 5(6)-carboxy-2′,7′-dichlorofluorescein diacetate (cDCF-DA; Sigma-Aldrich), an intracellular dye for that purpose .
Treatment of HUVECs with gHSA (25–100 μg/mL) for different times (4–12 h) induced significant increments of extracellular ROS production with respect to treatment with the same concentration of un-modified albumin (HSA, used as control) . The maximal response (i.e. the quantity of ROS) was obtained with 25 μg/mL gHSA after 4 h of treatment (Figure 1a). The effects of AGE-HSA were studied under the same conditions. AGE-HSA increased the extracellular ROS production at lower concentrations (12 μg/mL) and after shorter time of exposure than gHSA (2 h). Another important difference is that, at long incubation periods, the ROS-inducing effects of gHSA were maintained, whereas no significant increases on ROS production were observed with AGE-HSA at 4–8 h (Figure 1b).
Similar experiments were designed to measure the intracellular ROS production by using cDCF-DA after 4 h of treatment the HUVECs with gHSA or AGE-HSA (12–50 μg/mL). Interestingly, at 25 μg/mL, gHSA significantly enhanced the intracellular ROS production, whereas AGE-HSA only showed a trend to slightly increase it (Figure 2).
Therefore, differences in the induction of ROS production were observed between gHSA (a low glycated product) and AGE-HSA (a high glycated product). Although the effects of AGE-HSA are accepted to be mediated by RAGE, the receptor that mediates the effects of gHSA has not been revealed yet , since, the effects of gHSA are not mediated by RAGE .
2.2. Expression of adhesion molecules mediating leukocyte adhesion to endothelium
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 . Expression of inducible adhesion molecules is a final common pathway in the development of vascular inflammation and pathology, rendering the vasculature a selective target for circulating peripheral blood cells [27, 40].
A number of studies have demonstrated induction of vascular cell adhesion molecule-1 (VCAM-1) expression in a RAGE-dependent manner when endothelial cells are exposed to AGEs . Moreover, engagement of RAGE by AGEs results in enhanced expression of other adhesion molecules, such as E-selectin and intercellular cell adhesion molecule-1 (ICAM-1) [40, 41, 42]. High expression of adhesion molecules in endothelial cells may promote adhesive interactions of circulating monocytes with the endothelial surface, resulting, eventually, in transendothelial migration .
We confirmed that AGE-HSA up-regulated ICAM-1 and VCAM-1 expression more than gHSA, in terms of mRNA quantitative changes, measured by total messenger RNA retro-transcription and quantitative real-time polymerase chain reaction (qPCR) . Even while the effects of gHSA seemed to be limited to 4 h- treatment, AGE-HSA up-regulated VCAM-1 and ICAM-1 expression for longer periods of time (from 2 to 6 h). Differences on the active concentrations of both glycation products were also observed: whereas gHSA was only active at 25 μg/mL, AGE-HSA was also effective at 12 and 100 μg/mL (Figure 3).
To further confirm the increase in the expression of these adhesion molecules, protein levels of VCAM-1 and ICAM-1 were analyzed by western blot analysis after the treatment of HUVECs with two relevant concentrations of gHSA and AGE-HSA: 25 and 100 μg/mL, in comparison with the same concentrations of unmodified HSA and Ct-HSA, respectively. There was a significant elevation of VCAM-1 and ICAM-1 levels caused by the effect of both AGE-HSA concentrations tested. On the other hand, only the concentration of 25 μg/mL gHSA (but not 100 μg/mL) enhanced the ICAM-1 protein levels (Figure 4).
The functional translation of VCAM-1 and ICAM-1 up-regulation was analyzed by the adhesion of peripheral blood mononuclear cells (PBMCs) to HUVEC monolayers after treatment with both types of modified albumins for 4 h (Figure 5). After these treatments, the adhesion of calcein-AM-stained PBMCs to HUVEC monolayers after 1 h of incubation and washing of non-adhered PBMCs was quantified by fluorescence. In these conditions, gHSA (25 μg/mL) induced no significant effect in PBMCs adhesion in comparison with the control HSA. However, AGE-HSA (25 μg/mL) induced a significant increase in the adhesion of PBMC to HUVEC monolayers.
The effects of gHSA and AGE-HSA on PBMCs transmigration through HUVEC monolayers were studied in comparison to the ICAM-1 and VCAM-1 changes of expression. For these experiments HUVEC with transfected green fluorescent protein were grown until confluence onto transwells with 5 μm of pore size (Millipore). After treatment with AGE-HSA (25 and 100 μg/mL) for 4 h PBMCs were layered over the HUVECs and incubated at 37°C. TNF-α (10 ng/mL) was used as a positive control because it induces endothelial cell activation and promotes PBMCs transmigration through the endothelial monolayer. The number of transmigrated PBMCs were estimated by quantification of nuclei acids content with CyQUANT® GR dye (Molecular probes, Invitrogen) at the end of the experiment. Unless for the case of TNF-α, no changes were observed for any of the stimuli after 3 h of treatment. However, after 24 h of HUVEC incubation with 25 μg/mL AGE-HSA, a significant increase in the migration of PBMCs was observed as compared to control (Figure 6). On the contrary, higher concentration of AGE-HSA (100 μg/mL), showed no effect in the transmigration of PBMCs. The positive control with TNF-α increased the migration of PBMCs even more than after 3 h (Figure 6).
Given the results obtained in the adhesion molecules expression in HUVECs, another approach was performed repeating the study with
In the case of VCAM-1 expression, high-AGE HSA only induced an increase in the mRNA expression at 12.5 μg/mL with respect to healthy HSA and low-AGE HSA (Figure 7b;
PBMCs adhesion to HUVECs was also studied with
3. Potential implications for pharmacological modulation of AGE-RAGE axis activity
In an attempt to counteract the inflammatory effects of AGE-HSA, we selected three RAGE inhibitors: a soluble form of RAGE (sRAGE; R&D systems), used at 0.25, 0.5 and 1 ng/mL; a monoclonal antibody against RAGE (anti-RAGE; R&D systems), used at 5, 10 and 20 μg/mL; and the RAGE antagonist FPS-ZM1 (Calbiochem, Merck Millipore), used at 125, 250, 500 and 1000 nM. HUVECs were pre-treated with different concentrations of these inhibitors and 50 min later treated with 25 μg/mL AGE-HSA. The inhibitory effect of these agents on the expression of VCAM-1 and ICAM-1 in HUVECs was studied.
However, contrary to what we expected, blockade of RAGE by using sRAGE, anti-RAGE antibody and FPS-ZM1 was not sufficient to counteract the AGE-induced VCAM-1 and ICAM-1 up-regulation at any of the concentrations tested under our experimental conditions. Our results may suggest that on endothelium, other RAGE-independent mechanisms may also be acting to increase adhesion molecule expression and induce inflammation. Other possible explanation for these results is that the pharmacological tools actually available to block RAGE activity are not able to block the effects of AGEs at the endothelial level. However, the results obtained on
To investigate the effects of RAGE blockade in pathological conditions, many studies have used soluble forms of RAGE or anti-RAGE antibodies, which can antagonize RAGE-ligand interaction to competitively inhibit the activation of RAGE signaling [39, 44, 45]. Evidence from these studies has shown that RAGE blockade protected against various disease challenges. Soluble RAGE, which competes with cellular RAGE for ligand binding, has been able to reduce inflammatory responses in several models tested. Streptozotocin-induced diabetic apoE−/− mice treated with once daily injections of murine sRAGE showed suppressed acceleration of atherosclerotic lesions in a dose-dependent manner . In parallel with decreased atherosclerotic lesion area and the complexity of the atheroma plaque composition, the levels of tissue factor, VCAM-1, AGEs, and nuclear translocation of NF-kB were decreased in the aortas of sRAGE-treated mice [42, 46]. In other work, sRAGE-treated mice displayed significant stabilization of the lesion area at the aortic root. Compared with diabetic mice receiving albumin (placebo), those receiving sRAGE had significantly diminished activity of monocyte chemoattractant protein-1 (MCP-1), cyclooxygenase-2 (COX-2), VCAM-1 and matrix metalloprotease 9 (MMP-9) within aortic tissue . Similarly, administration of sRAGE resulted in a highly significant decrease in atherosclerotic lesion area in parallel with decreased vascular expression of pro-inflammatory RAGE ligand S100/calgranulins and VCAM-1 and MMPs . Moreover, sRAGE-treated non-diabetic mice displayed significantly decreased atherosclerosis and vascular inflammation [47, 48].
Further studies using anti-RAGE IgG fragments to block ligand binding to RAGE have confirmed these results, especially at the highest dose (up to 10 μg/mL) tested . Exposure of HUVECs to AGE-bovine serum albumin induced expression of VCAM-1 and increased adhesiveness of the monolayer for T lymphoblast of the Molt-4 cell line, which was inhibited by addition of anti-RAGE IgG or sRAGE . Activation of signaling pathway on endothelial cells by advanced oxidation products resulted in overexpression of VCAM-1 and ICAM-1 at both, gene and protein levels, something that was prevented by blocking RAGE with either anti-RAGE IgG or excess sRAGE . Administration of anti-RAGE IgG or sRAGE strongly blocked the increase in vascular permeability in diabetic rats injected with human diabetic red blood cells . Mice treated with sRAGE or anti-RAGE F(ab’)2 fragments displayed significantly lower intima/media ratio (a marker of negative vascular remodeling after injury) compared to vehicle-treated animal models of femoral artery injury . However, despite the fact that both, sRAGE and anti-RAGE IgG were able to reduce inflammatory responses in all models tested so far [42, 46, 50, 52], no significant decrease in ICAM-1 and VCAM-1 expression was observed after pre-treatment with soluble RAGE or anti-RAGE antibody, under our experimental conditions.
A recently developed high-affinity RAGE-specific inhibitor: FPS-ZM1 (N-benzyl-4-chloro-N-cyclohexylbenzamide; Calbiochem, Merck Millipore)  was also studied. This inhibitor was developed to interact with the ligand-binding domain of the receptor and block RAGE signaling. In our
It is worth mentioning that, most of the above-mentioned works did not elucidate the precise AGE(s) that trigger signal transduction mechanisms upon interacting with RAGE. Kislinger et al.  studied the effect of CML-adducts and showed that CML-mediated VCAM-1 expression on HUVECs was also suppressed in the presence of excess sRAGE or anti-RAGE IgG. Nevertheless, they suggest that the findings presented in their work do not rule out other specific AGE products of glycation or oxidation, such as pentosidine, pyralline, methylglyoxal, and imidazolone [55, 56, 57], which are present in our modified albumins. Additionally, they also specified that their findings do not rule out either the presence of other receptors or cellular interaction sites for CML adducts, being possible that other receptors for AGE [58, 59, 60] may also engage CML- and AGE-modified adducts. These situations might explain why no reduction in the up-regulation of adhesion molecules is observed after pre-treatment with sRAGE and anti-RAGE antibody under our experimental conditions.
Additionally, Amadori-modified albumin stimulates adhesion of monocytes to endothelial cells through enhanced transcription of the cell surface adhesion molecules E-selectin, VCAM-1 and ICAM-1 , implicating an initial endothelial cell activation occurring at atherosclerosis-prone vascular sites [62, 63]. However, Amadori products do not compete with AGE-albumin for binding to AGE receptors such as RAGE . Aortic endothelial cells express specific receptors for Amadori-modified albumin [37, 65]. Although less information is available for the receptor for Amadori products and signaling through Amadori-modified albumin receptors remains obscure, calnexin  and nucleophosmin [67, 68] have been reported to be the fructosyl-lysine specific binding proteins [66, 67, 68]. Binding of Amadori-modified albumin to calnexin-like receptors may participate in degradation and/or activation of signal transduction processes involved in mediating the biologic activities of Amadori-modified albumin . The E-selectin expression induced by Amadori-modified albumin was 10 or 20 times higher than that induced with three types of AGEs-HSAs and was not suppressed by anti-RAGE antibody . This would explain why RAGE antagonism would not counteract the increase in adhesion molecules expression.
In agreement with this hypothesis, Esposito et al.  found that anti-RAGE antibody completely prevented leukocyte adhesion to endothelial cells grown for 8 weeks in high-glucose-containing media, but it did not reduce the adhesion at 24 h. These results demonstrate that AGEs are important mediators of high-glucose-induced endothelial dysfunction after long-term exposure, whereas the same changes in acute exposure occur with the action of mediators other than AGEs. As the formation of Amadori products is highly probable after 24 h incubation in high glucose medium, but not the formation of AGEs, the effects on the inflammation parameters observed by Esposito et al. , and not prevented by anti-RAGE antibodies, might be due to the effect of the early glycated products, and not AGEs.
Besides from directly blocking RAGE, alternative pharmacological approaches might turn out to be more promising. Namely, it has been shown that both RAGE and sRAGE can be regulated by currently available pharmacological agents . Other drugs currently in use for diabetic complications have been shown to have an effect on AGE accumulation. These include the antihypertensive angiotensin-converting enzyme inhibitor (ACEI) ramipril  and the glucose-lowering drug metformin , which both reduce AGE. Forbes et al.  demonstrated that compared with placebo, the ACEI perindopril increased human plasma sRAGE levels and reduced plasma AGE concentrations, suggesting an additional mechanistic effect of ACE inhibition in the treatment and prevention of vascular disease. The inhibition of ACE in rats increased the renal expression of sRAGE and decreased the expression of renal full-length RAGE protein . These investigators also showed that plasma sRAGE levels were significantly increased by inhibition of ACE in both diabetic rats and human subjects with type 1 diabetes . Olmesartan, an angiotensin II type 1 receptor blocker, inhibited the AGE-evoked ROS generation and reduced the expression levels of monocyte chemoattractant protein 1 and ICAM-1 in endothelial cells, subsequently blocking T-cell adhesion to endothelial cells .
Other potential agents that may affect circulating sRAGE include the thiazolidinediones [76, 77] and statins [78, 79, 80], both of which are known to modulate AGE-RAGE axis. Marx et al.  investigated the effects of the two thiazolidinediones available, rosiglitazone and pioglitazone, on RAGE expression in HUVECs. Exposure of HUVECs to thiazolidinedione resulted in a similar reduction in RAGE mRNA expression, via inhibition of NF-κB activation, and in RAGE cell surface expression, demonstrating how these drugs may influence RAGE expression and its deleterious inflammatory activity in subjects with DM . Blockade of the interaction of S100A12 (an endogenous ligand of RAGE) with RAGE by statins at an early stage may prevent inflammation in atherosclerosis and counteract the harmful effects mediated by C reactive protein .
Finally, recent results testing new potential drugs have been reported. Curcumin, a polyphenolic natural compound is able to trap methylglyoxal, an important precursor of AGEs . Added on endothelial cell cultures curcumin reduced the intracellular ROS levels and improved cell viability compared with the treatment of methylglyoxal alone. There was also a significant reduction in the expression levels of ICAM-1 . Liquiritin, the 4’-O-glucoside of the flavanone liquiritigenin, reduced AGEs-induced apoptosis and ROS generation in HUVECs and also significantly increased AGEs-reduced SOD activity . It even down-regulated the RAGE protein expression and significantly blocked NF-κB activation .
Oxidative stress induction by AGEs at endothelium triggers molecular signaling pathways that produce an inflammatory response or even endothelial dysfunction. Adhesion molecules expression at the membrane surface of endothelial cells as a consequence of this response or induced by AGEs by other mechanisms mediates the adhesion of leukocytes to endothelium. This adhesion is a key step in the atherogenesis process and the possible involvement of AGE-RAGE axis in it should be considered as potential therapeutic target. Finally, possible pharmacological modulation of AGE-RAGE axis activity at the endothelium is suggested, but specific pharmacological tools available nowadays are not efficient enough; momentarily, drugs used for cardiovascular and metabolic problems could be helpful in modulating the AGE-RAGE axis.
This study was supported by the
Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: A systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016; 388(10053):1459-1544
Cahill PA, Redmond EM. Vascular endothelium—Gatekeeper of vessel health. Atherosclerosis. 2016; 248:97-109
Basta G, Schmidt AM, De Caterina R. Advanced glycation end products and vascular inflammation: Implications for accelerated atherosclerosis in diabetes. Cardiovascular Research. 2004; 63(4):582-592
Sena CM, Pereira AM, Seica R. Endothelial dysfunction—A major mediator of diabetic vascular disease. Biochimica et Biophysica Acta. 2013; 1832(12):2216-2231
Wautier JL, Schmidt AM. Protein glycation: A firm link to endothelial cell dysfunction. Circulation Research. 2004; 95(3):233-238
de Vos LC et al. Advanced glycation end products: An emerging biomarker for adverse outcome in patients with peripheral artery disease. Atherosclerosis. 2016; 254:291-299
Thornalley PJ et al. Quantitative screening of advanced glycation endproducts in cellular and extracellular proteins by tandem mass spectrometry. The Biochemical Journal. 2003; 375(Pt 3):581-592
Jaisson S, Gillery P. Evaluation of nonenzymatic posttranslational modification-derived products as biomarkers of molecular aging of proteins. Clinical Chemistry. 2010; 56(9):1401-1412
Ott C et al. Role of advanced glycation end products in cellular signaling. Redox Biology. 2014; 2:411-429
Degenhardt TP, Thorpe SR, Baynes JW. Chemical modification of proteins by methylglyoxal. Cellular and Molecular Biology (Noisy-le-Grand, France). 1998; 44(7):1139-1145
Cerami C et al. Tobacco smoke is a source of toxic reactive glycation products. Proceedings of the National Academy of Sciences of the United States of America. 1997; 94(25):13915-13920
Goldberg T et al. Advanced glycoxidation end products in commonly consumed foods. Journal of the American Dietetic Association. 2004; 104(8):1287-1291
Koschinsky T et al. Orally absorbed reactive glycation products (glycotoxins): An environmental risk factor in diabetic nephropathy. Proceedings of the National Academy of Sciences of the United States of America. 1997; 94(12):6474-6479
Yagmur E et al. Elevation of nepsilon-(carboxymethyl)lysine-modified advanced glycation end products in chronic liver disease is an indicator of liver cirrhosis. Clinical Biochemistry. 2006; 39(1):39-45
Prasad A, Bekker P, Tsimikas S. Advanced glycation end products and diabetic cardiovascular disease. Cardiology in Review. 2012; 20(4):177-183
Fukami K, Yamagishi S, Okuda S. Role of AGEs-RAGE system in cardiovascular disease. Current Pharmaceutical Design. 2014; 20(14):2395-2402
Chiang KH et al. Plasma levels of soluble receptor for advanced glycation end products are associated with endothelial function and predict cardiovascular events in nondiabetic patients. Coronary Artery Disease. 2009; 20(4):267-273
Basta G et al. Advanced glycation end products activate endothelium through signal-transduction receptor RAGE: A mechanism for amplification of inflammatory responses. Circulation. 2002; 105(7):816-822
Wautier MP et al. Activation of NADPH oxidase by AGE links oxidant stress to altered gene expression via RAGE. American Journal of Physiology. Endocrinology and Metabolism. 2001; 280(5):E685-E694
Yan SF, Ramasamy R, Schmidt AM. The RAGE Axis: A fundamental mechanism signaling danger to the vulnerable vasculature. Circulation Research. 2010; 106(5):842-853
Lubrano V, Balzan S. Roles of LOX-1 in microvascular dysfunction. Microvascular Research. 2016; 105:132-140
Shen GX. Mitochondrial dysfunction, oxidative stress and diabetic cardiovascular disorders. Cardiovascular & Hematological Disorders Drug Targets. 2012; 12(2):106-112
Ren X et al. Advanced glycation end-products decreases expression of endothelial nitric oxide synthase through oxidative stress in human coronary artery endothelial cells. Cardiovascular Diabetology. 2017; 16(1):52
Liu GD et al. The augmentation of O-GlcNAcylation reduces glyoxal-induced cell injury by attenuating oxidative stress in human retinal microvascular endothelial cells. International Journal of Molecular Medicine. 2015; 36(4):1019-1027
Chen J et al. C-reactive protein upregulates receptor for advanced glycation end products expression and alters antioxidant defenses in rat endothelial progenitor cells. Journal of Cardiovascular Pharmacology. 2009; 53(5):359-367
Morita M et al. Advanced glycation end products-induced reactive oxygen species generation is partly through NF-kappa B activation in human aortic endothelial cells. Journal of Diabetes and its Complications. 2013; 27(1):11-15
Guo ZJ et al. Advanced oxidation protein products activate vascular endothelial cells via a RAGE-mediated signaling pathway. Antioxidants & Redox Signaling. 2008; 10(10):1699-1712
Niiya Y et al. Advanced glycation end products increase permeability of brain microvascular endothelial cells through reactive oxygen species-induced vascular endothelial growth factor expression. Journal of Stroke and Cerebrovascular Diseases. 2012; 21(4):293-298
Niiya Y et al. Susceptibility of brain microvascular endothelial cells to advanced glycation end products-induced tissue factor upregulation is associated with intracellular reactive oxygen species. Brain Research. 2006; 1108(1):179-187
Ando R et al. Involvement of advanced glycation end product-induced asymmetric dimethylarginine generation in endothelial dysfunction. Diabetes & Vascular Disease Research. 2013; 10(5):436-441
Naser N et al. Advanced glycation end products acutely impair Ca(2+) signaling in bovine aortic endothelial cells. Frontiers in Physiology. 2013; 4:38
Schalkwijk CG, Miyata T. Early- and advanced non-enzymatic glycation in diabetic vascular complications: The search for therapeutics. Amino Acids. 2012; 42(4):1193-1204
Amore A et al. Amadori-configurated albumin induces nitric oxide-dependent apoptosis of endothelial cells: A possible mechanism of diabetic vasculopathy. Nephrology, Dialysis, Transplantation. 2004; 19(1):53-60
Amore A et al. Nonenzymatically glycated albumin (Amadori adducts) enhances nitric oxide synthase activity and gene expression in endothelial cells. Kidney International. 1997; 51(1):27-35
Paradela-Dobarro B et al. Key structural and functional differences between early and advanced glycation products. Journal of Molecular Endocrinology. 2016; 56(1):23-37
Rodino-Janeiro BK et al. Glycated albumin, a precursor of advanced glycation end-products, up-regulates NADPH oxidase and enhances oxidative stress in human endothelial cells: Molecular correlate of diabetic vasculopathy. Diabetes/Metabolism Research and Reviews. 2010; 26(7):550-558
Wu VY, Cohen MP. Identification of aortic endothelial cell binding proteins for Amadori adducts in glycated albumin. Biochemical and Biophysical Research Communications. 1993; 193(3):1131-1136
Zhang M et al. Glycated proteins stimulate reactive oxygen species production in cardiac myocytes: Involvement of Nox2 (gp91phox)-containing NADPH oxidase. Circulation. 2006; 113(9):1235-1243
Chuah YK et al. Receptor for advanced glycation end products and its involvement in inflammatory diseases. International Journal of Inflammation. 2013; 2013:403460
Schmidt AM et al. Advanced glycation endproducts interacting with their endothelial receptor induce expression of vascular cell adhesion molecule-1 (VCAM-1) in cultured human endothelial cells and in mice. A potential mechanism for the accelerated vasculopathy of diabetes. The Journal of Clinical Investigation. 1995; 96(3):1395-1403
Boulanger E et al. AGEs bind to mesothelial cells via RAGE and stimulate VCAM-1 expression. Kidney International. 2002; 61(1):148-156
Kislinger T et al. Receptor for advanced glycation end products mediates inflammation and enhanced expression of tissue factor in vasculature of diabetic apolipoprotein E-null mice. Arteriosclerosis, Thrombosis, and Vascular Biology. 2001; 21(6):905-910
Aronson D, Rayfield EJ. How hyperglycemia promotes atherosclerosis: Molecular mecha-nisms. Cardiovascular Diabetology. 2002; 1:1
Chen Y et al. Blockade of late stages of autoimmune diabetes by inhibition of the receptor for advanced glycation end products. Journal of Immunology. 2004; 173(2):1399-1405
Zeng S et al. Blockade of receptor for advanced glycation end product (RAGE) attenuates ischemia and reperfusion injury to the liver in mice. Hepatology. 2004; 39(2):422-432
Park L et al. Suppression of accelerated diabetic atherosclerosis by the soluble receptor for advanced glycation endproducts. Nature Medicine. 1998; 4(9):1025-1031
Bucciarelli LG et al. RAGE blockade stabilizes established atherosclerosis in diabetic apolipoprotein E-null mice. Circulation. 2002; 106(22):2827-2835
Wendt T et al. Receptor for advanced glycation endproducts (RAGE) and vascular inflammation: Insights into the pathogenesis of macrovascular complications in diabetes. Current Atherosclerosis Reports. 2002; 4(3):228-237
Liliensiek B et al. Receptor for advanced glycation end products (RAGE) regulates sepsis but not the adaptive immune response. The Journal of Clinical Investigation. 2004; 113(11):1641-1650
Wautier JL et al. Receptor-mediated endothelial cell dysfunction in diabetic vasculopathy. Soluble receptor for advanced glycation end products blocks hyperpermeability in diabetic rats. The Journal of Clinical Investigation. 1996; 97(1):238-243
Sakaguchi T et al. Central role of RAGE-dependent neointimal expansion in arterial restenosis. The Journal of Clinical Investigation. 2003; 111(7):959-972
Goova MT et al. Blockade of receptor for advanced glycation end-products restores effective wound healing in diabetic mice. The American Journal of Pathology. 2001; 159(2):513-525
Deane R et al. A multimodal RAGE-specific inhibitor reduces amyloid beta-mediated brain disorder in a mouse model of Alzheimer disease. The Journal of Clinical Investigation. 2012; 122(4):1377-1392
Kislinger T et al. N(epsilon)-(carboxymethyl)lysine adducts of proteins are ligands for receptor for advanced glycation end products that activate cell signaling pathways and modulate gene expression. The Journal of Biological Chemistry. 1999; 274(44):31740-31749
Sell DR, Monnier VM. Structure elucidation of a senescence cross-link from human extracellular matrix. Implication of pentoses in the aging process. The Journal of Biological Chemistry. 1989; 264(36):21597-21602
Njoroge FG, Sayre LM, Monnier VM. Detection of d-glucose-derived pyrrole compounds during Maillard reaction under physiological conditions. Carbohydrate Research. 1987; 167:211-220
Westwood ME, Thornalley PJ. Molecular characteristics of methylglyoxal-modified bovine and human serum albumins. Comparison with glucose-derived advanced glycation endproduct-modified serum albumins. Journal of Protein Chemistry. 1995; 14(5):359-372
Vlassara H, Bucala R. Recent progress in advanced glycation and diabetic vascular disease: Role of advanced glycation end product receptors. Diabetes. 1996; 45(Suppl 3):S65-S66
Araki N et al. Macrophage scavenger receptor mediates the endocytic uptake and degradation of advanced glycation end products of the Maillard reaction. European Journal of Biochemistry. 1995; 230(2):408-415
el Khoury J et al. Macrophages adhere to glucose-modified basement membrane collagen IV via their scavenger receptors. The Journal of Biological Chemistry. 1994; 269(14):10197-10200
Desfaits AC, Serri O, Renier G. Gliclazide reduces the induction of human monocyte adhesion to endothelial cells by glycated albumin. Diabetes, Obesity & Metabolism. 1999; 1(2):113-120
Dai G et al. Distinct endothelial phenotypes evoked by arterial waveforms derived from atherosclerosis-susceptible and -resistant regions of human vasculature. Proceedings of the National Academy of Sciences of the United States of America. 2004; 101(41):14871-14876
Nakashima Y et al. Upregulation of VCAM-1 and ICAM-1 at atherosclerosis-prone sites on the endothelium in the ApoE-deficient mouse. Arteriosclerosis, Thrombosis, and Vascular Biology. 1998; 18(5):842-851
Schmidt AM et al. Isolation and characterization of two binding proteins for advanced glycosylation end products from bovine lung which are present on the endothelial cell surface. The Journal of Biological Chemistry. 1992; 267(21):14987-14997
Wu VY, Cohen MP. Receptors specific for Amadori-modified glycated albumin on murine endothelial cells. Biochemical and Biophysical Research Communications. 1994; 198(2):734-739
Wu VY, Shearman CW, Cohen MP. Identification of calnexin as a binding protein for Amadori-modified glycated albumin. Biochemical and Biophysical Research Communications. 2001; 284(3):602-606
Krantz S et al. Purification and partial amino acid sequencing of a fructosyllysine-specific binding protein from cell membranes of the monocyte-like cell line U937. Biochimica et Biophysica Acta. 1995; 1266(1):109-112
Brandt R et al. Nucleophosmin is a component of the fructoselysine-specific receptor in cell membranes of Mono Mac 6 and U937 monocyte-like cells. Biochimica et Biophysica Acta. 2004; 1670(2):132-136
Higai K, Shimamura A, Matsumoto K. Amadori-modified glycated albumin predominantly induces E-selectin expression on human umbilical vein endothelial cells through NADPH oxidase activation. Clinica Chimica Acta. 2006; 367(1-2):137-143
Esposito C et al. Long-term exposure to high glucose up-regulates VCAM-induced endothelial cell adhesiveness to PBMC. Kidney International. 2001; 59(5):1842-1849
Koyama H, Yamamoto H, Nishizawa Y. RAGE and soluble RAGE: Potential therapeutic targets for cardiovascular diseases. Molecular Medicine. 2007; 13(11-12):625-635
Forbes JM et al. Reduction of the accumulation of advanced glycation end products by ACE inhibition in experimental diabetic nephropathy. Diabetes. 2002; 51(11):3274-3282
Sena CM et al. Metformin restores endothelial function in aorta of diabetic rats. British Journal of Pharmacology. 2011; 163(2):424-437
Forbes JM et al. Modulation of soluble receptor for advanced glycation end products by angiotensin-converting enzyme-1 inhibition in diabetic nephropathy. Journal of the American Society of Nephrology. 2005; 16(8):2363-2372
Yamagishi S et al. Olmesartan blocks inflammatory reactions in endothelial cells evoked by advanced glycation end products by suppressing generation of reactive oxygen species. Ophthalmic Research. 2008; 40(1):10-15
Marx N et al. Thiazolidinediones reduce endothelial expression of receptors for advanced glycation end products. Diabetes. 2004; 53(10):2662-2668
Tan KC et al. Thiazolidinedione increases serum soluble receptor for advanced glycation end-products in type 2 diabetes. Diabetologia. 2007; 50(9):1819-1825
Paradela-Dobarro B et al. Statins modulate feedback regulation mechanisms between advanced glycation end-products and C-reactive protein: Evidence in patients with acute myocardial infarction. European Journal of Pharmaceutical Sciences. 2013; 49(4):512-518
Okamoto T et al. Angiogenesis induced by advanced glycation end products and its prevention by cerivastatin. The FASEB Journal. 2002; 16(14):1928-1930
Cuccurullo C et al. Suppression of RAGE as a basis of simvastatin-dependent plaque stabilization in type 2 diabetes. Arteriosclerosis, Thrombosis, and Vascular Biology. 2006; 26(12):2716-2723
Mahajan N, Bahl A, Dhawan V. C-reactive protein (CRP) up-regulates expression of receptor for advanced glycation end products (RAGE) and its inflammatory ligand EN-RAGE in THP-1 cells: Inhibitory effects of atorvastatin. International Journal of Cardiology. 2010; 142(3):273-278
Sun YP et al. Curcumin inhibits advanced glycation end product-induced oxidative stress and inflammatory responses in endothelial cell damage via trapping methylglyoxal. Molecular Medicine Reports. 2016; 13(2):1475-1486
Zhang X et al. Liquiritin attenuates advanced glycation end products-induced endothelial dysfunction via RAGE/NF-kappaB pathway in human umbilical vein endothelial cells. Molecular and Cellular Biochemistry. 2013; 374(1-2):191-201