Importance of advanced glycation end products in diabetes-associated cardiovascular and renal disease (original) (raw)
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Advanced glycation end products and diabetic complications
Expert Opinion on Investigational Drugs, 2002
During long standing hyperglycaemic state in diabetes mellitus, glucose forms covalent adducts with the plasma proteins through a non-enzymatic process known as glycation. Protein glycation and formation of advanced glycation end products (AGEs) play an important role in the pathogenesis of diabetic complications like retinopathy, nephropathy, neuropathy, cardiomyopathy along with some other diseases such as rheumatoid arthritis, osteoporosis and aging. Glycation of proteins interferes with their normal functions by disrupting molecular conformation, altering enzymatic activity, and interfering with receptor functioning. AGEs form intra-and extracellular cross linking not only with proteins, but with some other endogenous key molecules including lipids and nucleic acids to contribute in the development of diabetic complications. Recent studies suggest that AGEs interact with plasma membrane localized receptors for AGEs (RAGE) to alter intracellular signaling, gene expression, release of pro-inflammatory molecules and free radicals. The present review discusses the glycation of plasma proteins such as albumin, fibrinogen, globulins and collagen to form different types of AGEs. Furthermore, the role of AGEs in the pathogenesis of diabetic complications including retinopathy, cataract, neuropathy, nephropathy and cardiomyopathy is also discussed.
Circulation Research, 2003
The formation of advanced glycation end products (AGEs) on extracellular matrix components leads to accelerated increases in collagen cross linking that contributes to myocardial stiffness in diabetes. This study determined the effect of the crosslink breaker, ALT-711 on diabetes-induced cardiac disease. Streptozotocin diabetes was induced in Sprague-Dawley rats for 32 weeks. Treatment with ALT-711 (10 mg/kg) was initiated at week 16. Diabetic hearts were characterized by increased left ventricular (LV) mass and brain natriuretic peptide (BNP) expression, decreased LV collagen solubility, and increased collagen III gene and protein expression. Diabetic hearts had significant increases in AGEs and increased expression of the AGE receptors, RAGE and AGE-R3, in association with increases in gene and protein expression of connective tissue growth factor (CTGF). ALT-711 treatment restored LV collagen solubility and cardiac BNP in association with reduced cardiac AGE levels and abrogated the increase in RAGE, AGE-R3, CTGF, and collagen III expression. The present study suggests that AGEs play a central role in many of the alterations observed in the diabetic heart and that cleavage of preformed AGE crosslinks with ALT-711 leads to attenuation of diabetes-associated cardiac abnormalities in rats. This provides a potential new therapeutic approach for cardiovascular disease in human diabetes. (Circ Res. 2003;92:785-792.)
Advanced Glycation End-Products and the Progress of Diabetic Vascular Complications
Physiological research / Academia Scientiarum Bohemoslovaca
Epidemiological studies have confirmed that hyperglycemia is the most important factor in the onset and progress of vascular complications, both in Type 1 and 2 diabetes mellitus. The formation of advanced glycation end-products (AGEs) correlates with glycemic control. The AGE hypothesis proposes that accelerated chemical modification of proteins by glucose during hyperglycemia contributes to the pathogenesis of diabetic complications including nephropathy, retinopathy, neuropathy and atherosclerosis. Recent studies have shown that increased formation of serum AGEs exists in diabetic children and adolescents with or without vascular complications. Furthermore, the presence of diabetic complications in children correlates with elevated serum AGEs. The level of serum AGEs could be considered as a marker of later developments of vascular complications in children with Type 1 and 2 diabetes mellitus. The careful metabolic monitoring of young diabetics together with monitoring of serum AGEs can provide useful information about impending AGE-related diabetic complications. It is becoming clear that anti-AGE strategies may play an important role in the treatment of young and older diabetic patients. Several potential drug candidates such as AGE inhibitors have been reported recently.
Recent Advances in Cardiovascular Drug Discovery (Formerly Recent Patents on Cardiovascular Drug Discovery), 2016
Diabetes is a major risk factor for cardiovascular disease, and recent advances in research indicate that a detailed understanding of the pathophysiology of its effects is mandatory to reduce diabetes-related mortality and morbidity. Advanced Glycation End Products (AGEs) play a central role in the genesis and progression of complications of both type 1 and type 2 diabetes mellitus, and have been found to be important even in non-diabetic patients as a marker of cardiovascular disease. AGEs have a profound impact on patient's prognosis regardless of the glycemic control, and therefore pharmacologic approaches against AGEs accumulation have been proposed over the years to treat cardiovascular diseases, parallel to a more detailed understanding of AGEs pathophysiology. Compounds with anti-AGEs effects are currently under investigation in both pre-clinical and clinical scenarios, and many of the drugs previously used to treat specific diseases have been found to have AGE-inhibitory effects. Some products are still in "bench evaluation", whereas others have been already investigated in clinical trials with conflicting evidences. This review aims at summarizing the mechanisms of AGEs formation and accumulation, and the most relevant issues in pre-clinical and clinical experiences in anti-AGEs treatment in cardiovascular research.
Diabetologia, 1999
Extracellular matrix expansion and vascular hypertrophy have been implicated in the pathogenesis of the microvascular complications of diabetes [1]. The formation of long-lived non-enzymatically glycated proteins has been postulated as a fundamental mechanism in the pathogenesis of these complications [2]. Aminoguanidine (AG) is a hydrazine-like compound which inhibits the formation of advanced glycation end-products (AGEs). This phenomenon has been shown to occur in vivo. Aminoguanidine treatment in humans leads to a reduction in AGE-haemoglobin without influencing the Amadori product, glycated haemoglobin [3]. Aminoguanidine has been shown to retard the development of nephropathy and retinopathy in experimental diabetes [4, 5]. More recently, it has been shown that aminoguanidine attenuates Diabetologia (1999) 42: 472±479
Advanced glycation endproducts—role in pathology of diabetic complications
Diabetes Research and Clinical Practice, 2005
Diabetes mellitus is a common endocrine disorder characterised by hyperglycaemia and predisposes to chronic complications affecting the eyes, blood vessels, nerves and kidneys. Hyperglycaemia has an important role in the pathogenesis of diabetic complications by increasing protein glycation and the gradual build-up of advanced glycation endproducts (AGEs) in body tissues. These AGE form on intra-and extracellular proteins, lipids, nucleic acids and possess complex structures that generate protein fluorescence and cross-linking. Protein glycation and AGE are accompanied by increased free radical activity that contributes towards the biomolecular damage in diabetes. There is considerable interest in receptors for AGEs (RAGE) found on many cell types, particularly those affected in diabetes. Recent studies suggest that interaction of AGEs with RAGE alter intracellular signalling, gene expression, release of pro-inflammatory molecules and free radicals that contribute towards the pathology of diabetic complications. This review introduces the chemistry of glycation and AGEs and examines the mechanisms by which they mediate their toxicity. The role of AGEs in the pathogenesis of retinopathy, cataract, atherosclerosis, neuropathy, nephropathy, diabetic embryopathy and impaired wound healing are considered. There is considerable interest in anti-glycation compounds because of their therapeutic potential. The mechanisms and sites of action of selected inhibitors, together with their potential in preventing diabetic complications are discussed.
Evolving concepts in advanced glycation, diabetic nephropathy, and diabetic vascular disease
Archives of Biochemistry and Biophysics, 2003
Advanced glycation endproducts (AGEs) have been postulated to play a role in the development of both nephropathy and large vessel disease in diabetes. However, it is still not clear which AGE subtypes play a pathogenetic role and which of several AGE receptors mediate AGE effects on cells. This review summarises the renoprotective effect of inhibitors of AGE formation, including aminoguanidine, and of cross-link breakers, including ALT-711, on experimental diabetic nephropathy and on mesenteric vascular hypertrophy. It also demonstrates similar effects of aminoguanidine and ramipril (an angiotensin converting enzyme inhibitor) on fluorescent and immunoassayable AGE levels, renal protein kinase C activity, nitrotyrosine expression, lysosomal function, and protein handling in experimental diabetes. These findings indicate that inhibition of the renin angiotensin system blocks both upstream and downstream pathways leading to tissue injury. We postulate that the chemical pathways leading to advanced glycation endproduct formation and the renin angiotensin systems may interact through the generation of free radicals, induced both by glucose and angiotensin II. There is also evidence to suggest that AGE-dependent pathways may play a role in the development of tubulointerstitial fibrosis in the diabetic kidney. This effect is mediated through RAGE and is TGF-b and CTGF-dependent.
Cardiovascular Research, 2004
The formation of advanced glycation end products (AGEs) is an important biochemical abnormality that accompanies diabetes mellitus and, likely, inflammation in general. Here we summarize and discuss recent studies indicating that the effects of AGEs on vessel wall homeostasis may account for the rapidly progressive atherosclerosis associated with diabetes mellitus. Driven by hyperglycemia and oxidant stress, AGEs form to a greatly accelerated degree in diabetes. Within the vessel wall, collagen-linked AGEs may ''trap'' plasma proteins, quench nitric oxide (NO) activity and interact with specific receptors to modulate a large number of cellular properties. On plasma low density lipoproteins (LDL), AGEs initiate oxidative reactions that promote the formation of oxidized LDL. Interaction of AGEs with endothelial cells as well as with other cells accumulating within the atherosclerotic plaque, such as mononuclear phagocytes and smooth muscle cells (SMCs), provides a mechanism to augment vascular dysfunction. Specifically, the interaction of AGEs with vessel wall components increases vascular permeability, the expression of procoagulant activity and the generation of reactive oxygen species (ROS), resulting in increased endothelial expression of endothelial leukocyte adhesion molecules. AGEs potently modulate initiating steps in atherogenesis involving blood-vessel wall interactions, triggering an inflammatory-proliferative process and, furthermore, critically contribute to propagation of inflammation and vascular perturbation in established disease. Thus, a better understanding of the biochemical mechanisms by which AGEs contribute to such processes in the vessel wall could be relevant to devise preventive and therapeutic strategies for diabetic atherosclerosis.
Diabetic Retinopathy [Working Title], 2019
Hyperglycemic conditions and disruptions to glucose-regulating pathways lead to increased formation of highly reactive aldehydes, methylglyoxal and glyoxal, which react with certain arginine and lysine residues in proteins to form advanced glycation end products (AGEs). These AGEs damage the integrity of the retinal vasculature predominantly through two mechanisms: non-receptor-mediated damage, which pertains to the interaction with extracellular matrix and its functional properties, and receptor-mediated damage through AGE interactions with their receptors (RAGE) on pericytes and Muller cells. Damage occurring between AGE and RAGE potentially generates reactive oxygen species, inflammatory cytokines, and growth factors. Both mechanisms result in increased permeability of endothelial tight junctions, and this increased permeability can lead to leaking and eventually ischemia. Once this ischemia becomes significant, neovascularization can occur, the hallmark of proliferative diabetic...