RESUMO
Diabetes is associated with increased risk of cardiovascular disease. Advanced glycation end-products (AGEs) are considered to be a major pathogenic factor for diabetic vascular complications. The levels of AGEs are increased in diabetic patients. We have studied the presence of the major AGE methylglyoxal (MGO)-derived hydroimidazolone in human aorta and carotid arteries, using immunohistochemistry (IHC), western blotting and mass spectrometry. By IHC, MGO-derived modifications were detected mainly associated with cells in intimal thickenings and cells in microvessels in adventitia. In type V lesions MGO-derived AGE was also present, extracellular in the necrotic core and in cells at the border of the core. The highest degree of modification was probably associated with cell nuclei. By western blotting and mass spectrometry fibrin(ogen), the cytoskeleton-associated protein moesin and the nuclear proteins lamin A and C were identified as putative main targets for MGO-derived modification. LC-MS/MS studies of fibrin(ogen) modified in vitro with low concentrations of MGO identified the sites that were most prone to modification. These results indicate that AGE modifications occur preferentially on specific proteins. The modification of these proteins may play a role in vascular dysfunction and development of atherosclerosis in diabetes.
Assuntos
Aorta/química , Artéria Carótida Primitiva/química , Angiopatias Diabéticas/metabolismo , Fibrina/análise , Fibrinogênio/análise , Produtos Finais de Glicação Avançada/análise , Imidazóis/análise , Aldeído Pirúvico/análise , Idoso , Idoso de 80 Anos ou mais , Sequência de Aminoácidos , Aorta/patologia , Western Blotting , Artéria Carótida Primitiva/patologia , Estudos de Casos e Controles , Cromatografia Líquida , Angiopatias Diabéticas/patologia , Elasticidade , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Necrose , Noruega , Processamento de Proteína Pós-Traducional , Proteômica/métodos , Espectrometria de Massas em TandemRESUMO
PURPOSE: We aimed to investigate associations between serum levels of the advanced glycation endproduct methylglyoxal-derived hydroimidazolone (MG-H1) and retinopathy in a sample of patients with type 1 diabetes. METHODS: We conducted a cross-sectional study in a Scandinavian ophthalmology outpatient clinic on 61 randomly selected patients with type 1 diabetes. Blood samples and retinal photographs were taken at the same visit. Serum levels of hydroimidazolone immunoreactivity were determined using an immunoassay, and levels of retinopathy were determined from seven standard field stereo photographs of each eye according to the ETDRS method. Results were compared between patients with and without retinopathy. RESULTS: Hydroimidazolone quartiles were significantly associated with retinopathy (p = 0.013). The most profound increase in occurrence of retinopathy was observed from the lowest to the second-lowest hydroimidazolone quartile. Adjusted for duration of diabetes using logistic regression, a significant difference in the presence of retinopathy was found when comparing the lowest quartile with the rest (p = 0.022). CONCLUSIONS: In our patients with type 1 diabetes, serum levels of hydroimidazolone were found to be associated with retinopathy. This is in keeping with findings in a larger sample of patients with type 2 diabetes.
