RESUMO
Previously, we found that advanced glycation endproducts (AGEs) directly interact with tumor necrosis factor (TNF)-like weak inducer of apoptosis, a cytokine that controls inflammation, and that this interaction inhibited its action. This finding raised the novel possibility that AGEs alter the function of other cytokines through direct interaction. To investigate this possibility, we performed comprehensive screening for candidates that interacted with AGEs using protein array analysis. The array analysis revealed that high mobility group box-1 (HMGB1) had a markedly high affinity for AGEs. HMGB1 is a representative proinflammatory damage-associated molecular pattern molecule, and is reported to interact with lipopolysaccharide (LPS) directly to exert its inflammatory function. When LPS, HMGB1, and AGEs were mixed, the mobility of HMGB1 had shifted significantly in native PAGE, suggesting that these three molecules formed a triplet complex. The addition of AGEs to the LPS-HMGB1 mixture synergistically potentiated LPS-HMGB1-stimulated TNF-α mRNA expression in macrophage-like RAW264.7 cells. In addition, using receptor knockout clones, the increased proinflammatory response by LPS-HMGB1-AGEs complex was demonstrated to be mediated via Toll-like receptor 4 and receptor for AGEs. Taken together, this study suggested that AGEs carry out their pathophysiological roles by potentiating the LPS-HMGB1-stimulated proinflammatory response through direct interactions.
Assuntos
Produtos Finais de Glicação Avançada/metabolismo , Proteína HMGB1/metabolismo , Lipopolissacarídeos/toxicidade , Animais , Produtos Finais de Glicação Avançada/agonistas , Proteína HMGB1/agonistas , Inflamação/induzido quimicamente , Inflamação/metabolismo , Inflamação/patologia , Camundongos , Células RAW 264.7RESUMO
Advanced glycation end-products (AGEs), which comprise non-enzymatically glycosylated proteins, lipids, and nucleic acid amino groups, play an important role in several diseases and aging processes including angiopathy, renal failure, diabetic complications, and neurodegenerative diseases. Among AGE-associated phenotypes, toxic AGEs, glyceraldehyde-derived AGE-2, and glycolaldehyde-derived AGE-3 are involved in the pathogenesis of diabetic complications. In addition, macrophages are reported to remove extracellular AGEs from tissues via scavenger receptors, leading to the progression of atherosclerosis. In the present study, we found that AGE-2 and AGE-3 enhanced their own endocytic uptake by RAW264.7 mouse macrophage-like cells in a concentration-dependent manner. Furthermore, we demonstrated, for the first time, the morphology of phagocytic macrophages and the endocytosis of AGE particles. The toxic AGEs induced the expression of a scavenger receptor, CD204/scavenger receptors-1 class A (SR-A). Notably, an antibody against CD204 significantly prevented toxic AGE uptake. Moreover, an SR-A antagonistic ligand, fucoidan, also attenuated the AGE-2- and AGE-3-evoked uptake in a concentration-dependent manner. These results indicated that SR-A stimulation, at least in part, plays a role in AGE uptake.
Assuntos
Acetaldeído/análogos & derivados , Produtos Finais de Glicação Avançada/genética , Gliceraldeído/metabolismo , Processamento de Proteína Pós-Traducional , Receptores Depuradores Classe A/genética , Acetaldeído/metabolismo , Animais , Anticorpos Neutralizantes/farmacologia , Endocitose/efeitos dos fármacos , Regulação da Expressão Gênica , Produtos Finais de Glicação Avançada/agonistas , Produtos Finais de Glicação Avançada/imunologia , Camundongos , Fagocitose/efeitos dos fármacos , Polissacarídeos/farmacologia , Células RAW 264.7 , Receptores Depuradores Classe A/antagonistas & inibidores , Receptores Depuradores Classe A/imunologiaRESUMO
Ageing is a strong independent risk factor for disability, morbidity and mortality. Post-mitotic cells including those in the heart are a particular risk to age-related deterioration. As the occurrence of heart disease is increasing rapidly with an ageing population, knowledge regarding the mechanisms of age-related cardiac susceptibility and possible therapeutic interventions needs to be acquired to prevent advancing levels of heart disease. To understand more about the ageing heart, numerous aged animal models are being used to explore the underlying mechanisms. Due to time-consuming for investigations involving naturally aged animals, mimetic ageing models are being utilized to assess the related effects of ageing on disease occurrence. d-galactose is one of the substances used to instigate ageing in various models, and techniques involving this have been widely used since 1991. However, the mechanism through which d-galactose induces ageing in the heart remains unclear. The aim of this review was to comprehensively summarize the current findings from in vitro and in vivo studies on the effects of d-galactose-induced ageing on the heart, and possible therapeutic interventions against ageing heart models. From this review, we hope to provide invaluable information for future studies and based on the findings from experiments involving animals, we can inform possible therapeutic strategies for the prevention of age-related heart diseases in clinical settings.
Assuntos
Envelhecimento/efeitos dos fármacos , Cálcio/metabolismo , Galactose/administração & dosagem , Produtos Finais de Glicação Avançada/genética , Coração/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Envelhecimento/genética , Envelhecimento/metabolismo , Envelhecimento/patologia , Animais , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/genética , Cardiotônicos/farmacologia , Regulação da Expressão Gênica , Produtos Finais de Glicação Avançada/agonistas , Produtos Finais de Glicação Avançada/metabolismo , Coração/fisiopatologia , Humanos , Camundongos , Mitocôndrias Cardíacas/efeitos dos fármacos , Mitocôndrias Cardíacas/metabolismo , Mitocôndrias Cardíacas/patologia , Modelos Animais , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Estresse Oxidativo , Ratos , Espécies Reativas de Oxigênio/agonistas , Espécies Reativas de Oxigênio/antagonistas & inibidores , Espécies Reativas de Oxigênio/metabolismo , Proteína Supressora de Tumor p53/agonistas , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , beta-Galactosidase/genética , beta-Galactosidase/metabolismoRESUMO
Methylglyoxal (MG) is generated from glycolytic metabolites, lipid peroxidation, glucose autooxidation and protein glycation. It is a prooxidant inducing oxidative stress and formation of advanced glycation end products (AGE). Effect of carnosine (CAR) as an antioxidant on toxicity due to MG has generated interest. In this study, rats were given incrementally increased doses (100-300 mg/kg) of MG in drinking water for ten weeks. CAR (250 mg/kg i.p.) was administered with MG. Plasma thiobarbituric reactive substances (TBARS), protein carbonyl (PC), advanced oxidation protein products (AOPP) and AGE levels were elevated by MG, and CAR decreased PC, AOPP and AGE levels. MG increased liver reactive oxygen species (ROS), TBARS, PC and AOPP levels, which were decreased by CAR. Thus, in vivo role of CAR on chronic MG administration was observed to suppress the generated hepatic and plasma oxidative stress.
Assuntos
Produtos da Oxidação Avançada de Proteínas/antagonistas & inibidores , Antioxidantes/farmacologia , Carnosina/farmacologia , Produtos Finais de Glicação Avançada/antagonistas & inibidores , Fígado/efeitos dos fármacos , Aldeído Pirúvico/antagonistas & inibidores , Produtos da Oxidação Avançada de Proteínas/agonistas , Produtos da Oxidação Avançada de Proteínas/metabolismo , Animais , Produtos Finais de Glicação Avançada/agonistas , Produtos Finais de Glicação Avançada/metabolismo , Injeções Intraperitoneais , Peroxidação de Lipídeos/efeitos dos fármacos , Fígado/metabolismo , Masculino , Estresse Oxidativo/efeitos dos fármacos , Carbonilação Proteica , Aldeído Pirúvico/toxicidade , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/agonistas , Espécies Reativas de Oxigênio/antagonistas & inibidores , Espécies Reativas de Oxigênio/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
Methylglyoxal (MG), a highly reactive metabolite of hyperglycemia, can enhance protein glycation, oxidative stress or inflammation. The present study investigated the effects of apocynin on the mechanisms associated with MG toxicity in osteoblastic MC3T3-E1 cells. Pretreatment of MC3T3-E1 cells with apocynin prevented the MG-induced protein glycation and formation of intracellular reactive oxygen species and mitochondrial superoxide in MC3T3-E1 cells. In addition, apocynin increased glutathione levels and restored the activity of glyoxalase I inhibited by MG. These findings suggest that apocynin provide a protective action against MG-induced cell damage by reducing oxidative stress and by increasing the MG detoxification system. Apocynin treatment decreased the levels of proinflammatory cytokines such as tumor necrosis factor-α and interleukin-6 induced by MG. Additionally, the nitric oxide level reduced by MG was significantly increased by apocynin. These findings indicate that apocynin might exert its therapeutic effects via upregulation of glyoxalase system and antioxidant activity. Taken together, apocynin may prove to be an effective treatment for diabetic osteopathy.
Assuntos
Acetofenonas/farmacologia , Anti-Inflamatórios não Esteroides/farmacologia , Produtos Finais de Glicação Avançada/antagonistas & inibidores , Hipoglicemiantes/farmacologia , Osteoblastos/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Aldeído Pirúvico/antagonistas & inibidores , Células 3T3 , Animais , Sobrevivência Celular/efeitos dos fármacos , Células Clonais , Citocinas/antagonistas & inibidores , Citocinas/metabolismo , Glutationa/agonistas , Glutationa/metabolismo , Produtos Finais de Glicação Avançada/agonistas , Produtos Finais de Glicação Avançada/metabolismo , Glicosilação/efeitos dos fármacos , Humanos , Lactoilglutationa Liase/antagonistas & inibidores , Lactoilglutationa Liase/química , Lactoilglutationa Liase/genética , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/imunologia , Mitocôndrias/metabolismo , Óxido Nítrico/agonistas , Óxido Nítrico/antagonistas & inibidores , Óxido Nítrico/metabolismo , Osteoblastos/imunologia , Osteoblastos/metabolismo , Aldeído Pirúvico/metabolismo , Espécies Reativas de Oxigênio/antagonistas & inibidores , Espécies Reativas de Oxigênio/metabolismo , Superóxidos/antagonistas & inibidores , Superóxidos/metabolismoRESUMO
Advanced glycation end-products (AGE) have been implicated in aging and the pathogenesis of diabetic complications, inflammation, Alzheimer's disease, and cancer. AGE engage the cell surface receptor for AGE (RAGE), which in turn elicits intracellular signaling, leading to activation of NF-κB to cause deterioration of tissue homeostasis. AGE are not only formed within our bodies but are also derived from foods, endowing them with flavor. In the present study, we assessed the agonistic/antagonistic effects of food-derived AGE on RAGE signaling in a reporter assay system and found that low-molecular weight AGE can antagonize the action of AGE-BSA. Foods tested were Japanese soy sauce, coffee, cola, and red wine, all of which showed fluorescence characteristics of AGE. Soy sauce and coffee contained N(ε)-carboxymethyl-lysine (CML). Soy sauce, coffee, and red wine inhibited the RAGE ligand-induced activation of NF-κB, whereas cola had no effect on the ligand induction of NF-κB. The liquids were then fractionated into high-molecular weight (HMW) fractions and low-molecular weight (LMW) fractions. Soy sauce-, coffee-, and red wine-derived LMW fractions consistently inhibited the RAGE ligand induction of NF-κB, whereas the HMW fractions of these foods activated RAGE signaling. Using the LMW fraction of soy sauce as a model food-derived RAGE antagonist, we performed a plate-binding assay and found that the soy sauce LMW fractions competitively inhibited AGE-RAGE association. Further, this fraction significantly reduced AGE-dependent monocyte chemoattractant protein-1 (MCP-1) secretion from murine peritoneal macrophages. The LMF from soy sauce suppressed the AGE-induced RAGE trafficking to lipid rafts. These results indicate that small components in some, if not all, foods antagonize RAGE signaling and could exhibit beneficial effects on RAGE-related diseases.
Assuntos
Produtos Finais de Glicação Avançada/metabolismo , Microdomínios da Membrana/metabolismo , Receptores Imunológicos/agonistas , Alimentos de Soja/análise , Animais , Linhagem Celular , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Regulação para Baixo , Produtos Finais de Glicação Avançada/agonistas , Humanos , Microdomínios da Membrana/genética , Camundongos , Peso Molecular , NF-kappa B/genética , NF-kappa B/metabolismo , Transporte Proteico , Ratos , Receptor para Produtos Finais de Glicação Avançada , Receptores Imunológicos/metabolismo , Transdução de SinaisRESUMO
Alpha-lipoic acid (ALA) is widely used as an antioxidant for the treatment of diabetes and its complications; however, the pro-oxidant potential of ALA has recently been reported. This study was designed to investigate whether ALA supplementation could have pro-oxidant effects on cardiac tissues in normal and diabetic rats. Diabetes was induced by a single dose of streptozotocin (STZ; 55 mg/kg (intraperitoneal). Diabetic and normal rats were treated with ALA (100 mg kg(-1) day(-1)) for 45 days. ALA supplementation resulted in oxidative protein damage as evident by significant reduction in the cardiac levels of protein thiol in ALA-treated normal rats (P < 0.01) together with a significant elevation (P < 0.001) in the plasma levels of advanced oxidation protein products in ALA-treated normal rats and in ALA + STZ-diabetic rats compared with the normal control rats. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase has emerged as the major source of superoxide anion and enhanced oxidative damage in heart failure. ALA supplementation increased the myocardial immunoreactivity of p47phox subunit of NADPH oxidase in both normal nondiabetic and diabetic rats reflecting its pro-oxidant effect. Data showed that ALA supplementation failed to prevent cardiac complications in diabetic rats and led to cardiac toxicity in normal rats as indicated by pathological changes (cellular infiltration, fibrosis, and degeneration) and by the elevation of serum cardiac biomarkers compared with normal controls. The pro-oxidant effects of ALA suggest that careful selection of appropriate doses of ALA in reactive oxygen species-related diseases are critical.
Assuntos
Diabetes Mellitus Experimental/metabolismo , Insuficiência Cardíaca/metabolismo , Miocárdio/metabolismo , NADPH Oxidases/metabolismo , Oxidantes/efeitos adversos , Espécies Reativas de Oxigênio/agonistas , Ácido Tióctico/efeitos adversos , Animais , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/patologia , Produtos Finais de Glicação Avançada/agonistas , Produtos Finais de Glicação Avançada/sangue , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/patologia , Masculino , Malondialdeído/metabolismo , Miocárdio/patologia , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Estreptozocina , Triglicerídeos/sangue , Troponina I/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Chronic hyperglycemia, which is present in all types of diabetes, increases the formation of advanced glycation end-products (AGEs). The interaction of AGEs with receptor of advanced glycation end-products (RAGE) initiates a cascade of pro-inflammatory and pro-coagulant processes that result in oxidative stress, stimulating the formation and accumulation of more AGE molecules. This cyclic process, denominated metabolic memory, may explain the persistency of diabetic vascular complications in patients with satisfactory glycemic control. The RAGE found in several cell membranes is also present in soluble isoforms (esRAGE and cRAGE), which are generated by alternative deoxyribonucleic acid splicing or by proteolytic cleavage. This review focuses on new research into these mediators as potential biomarkers for vascular complications in diabetes.
A hiperglicemia crônica, presente em todas as formas de diabetes, favorece a formação de produtos finais de glicação avançada (AGEs). A interação de AGEs com o receptor de produtos finais glicosilados (RAGE) inicia uma cascata de processos pró-inflamatórios e pró-coagulantes que resultam em estresse oxidativo, o qual estimula a formação e o acúmulo de maior quantidade de moléculas de AGEs. Esse processo cíclico, denominado memória metabólica, pode explicar por que, mesmo após um período de bom controle glicêmico, as complicações vasculares associadas ao diabetes não regridem. O RAGE fixado nas membranas de várias células também está presente em isoformas solúveis (esRAGE e cRAGE), geradas por processamento alternativo do ácido desoxirribonucleico (DNA) ou por clivagem proteolítica. Esta revisão aborda os novos estudos sobre a função desses mediadores como potenciais biomarcadores para as complicações vasculares no diabetes.
Assuntos
Complicações do Diabetes , Isoformas de Proteínas , Produtos Finais de Glicação Avançada/agonistasRESUMO
Advanced glycation end-products (AGEs) are involved in the pathogenesis of numerous affections such as diabetes and neurological diseases. AGEs are also implied in various changes in tissues and organs. Therefore, compounds able to break them or inhibit their formation may be considered as potential drugs, dietary supplements, or bioactive additives. In this study, we have developed a rapid and reliable (Z' factor calculation) anti-AGEs activity screening based on the overall fluorescence of AGEs. This method was successfully evaluated on known AGEs inhibitors and on a small library of natural compounds, yielding coherent results when compared with literature data.
Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Produtos Finais de Glicação Avançada/agonistas , Produtos Finais de Glicação Avançada/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/química , Automação , Avaliação Pré-Clínica de Medicamentos/instrumentação , Fluorescência , Produtos Finais de Glicação Avançada/químicaRESUMO
Retinal ganglion cell degeneration is supposed to be mediated by reactive oxygen species (ROS) and advanced glycation end products (AGEs). The alpha2-adrenergic agonist, 5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (brimonidine; UK-14,304), is said to exert a neuroprotective effect. To investigate these mechanisms in detail, we exposed rat whole mounts to glyoxal or H(2)O(2) and treated them with either UK-14,304 alone or additionally with the phosphatidylinositide 3 kinase (PI3) kinase inhibitor, 2-(4-Morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (Ly 294002). The accumulation of Nepsilon-[carboxymethyl] lysine (CML) was assessed immunohistochemically and changes in intracellular pH (pHi), mitochondrial transmembrane potential (MTMP) and ROS production in cell bodies of multipolar ganglion cell layer were studied by intravital fluorescence microscopy and confocal laser scanning microscopy. Ultrastructural changes in mitochondria of multipolar ganglion cell layer cell bodies were determined by transmission electron microscopy. We found that glyoxal and H(2)O(2) increased accumulation of CML-modified proteins and ROS production and decreased pHi and MTMP in cell bodies of multipolar ganglion cell layer. UK-14,304 could prevent production of ROS, accumulation of CML-modified proteins, ameliorate acidification, preserve MTMP and attenuate ultrastructural damages of ganglion cell mitochondria. Ly 294002 reversed the UK-14,304-mediated attenuation of CML and ROS production. We conclude that the protective effects of UK-14,304 seem partly to be mediated by PI3 kinase-dependent pathways.