Junnosuke Miura

Serum levels of non-carboxymethyllysine advanced glycation endproducts are correlated to severity of microvascular complications in patients with Type 1 diabetes

We investigated whether serum levels of N-(carboxymethyl)lysine (CML), non-CML advanced glycation endproducts (AGEs), or pentosidine are associated with severity of diabetic microvascular complications in patients with Type 1 diabetes. Serum levels of CML, non-CML AGE, and pentosidine were measured by an enzyme-linked immunosorbent assay in 38 males and 47 females aged 31+/-8 years (mean+/-S.D.) with Type 1 diabetes for 18.7+/-7.0 years. There was a significant correlation between serum levels of CML or non-CML AGE and current HbA(1c) level (P<.01 and P<.05, respectively). The serum levels of non-CML AGE, but not CML or pentosidine, were significantly increased as normal renal status advanced to microalbuminuria, clinical nephropathy, and hemodialysis (P<.0001) and were positively correlated with urinary albumin excretion (UAE) in patients with Type 1 diabetes (P<.0001). A significant elevation of serum non-CML AGE was found in association with the severity of diabetic retinopathy (P<.0001). We found in the present study that CML levels were also increased in the stage of simple retinopathy, the early stage of clinically evident retinopathy (P<.05). Serum levels of non-CML AGE were significantly associated with the severity of diabetic nephropathy and retinopathy, suggesting a role of non-CML AGE in the progression of microvascular complications in patients with Type 1 diabetes. Since serum levels of CML were significantly increased in patients with simple retinopathy, CML may participate in the initiation of diabetic retinopathy.

Differences in the humoral autoreactivity to zinc transporter 8 between childhood- and adult-onset type 1 diabetes in Japanese patients

The aim of this study was to evaluate the humoral autoreactivity to zinc transporter 8 (ZnT8) depending on the clinical phenotype of type 1 diabetes (T1D). ZnT8 autoantibodies (ZnT8A) were determined by radioimmunoassay using carboxy-terminal ZnT8 constructs in 57 childhood-onset, 97 adult-onset, and 85 fulminant T1D. The ZnT8A frequency was higher in childhood-onset patients and decreased with increasing age of onset from 70% to 24% (P(trend)<0.005). None of the patients with fulminant T1D was positive for ZnT8A. There were at least two distinct ZnT8A epitope patterns associated with the aa325-restriction, childhood-onset patients have aa325-nonrestricted response more frequently compared to the adult-onset group (P<0.05). The level of ZnT8A was inversely associated with the copy number of HLA-DR4 allele (P<0.05). These results suggest differences in the humoral autoreactivity to ZnT8 depending on the clinical phenotype, which should provide strategy for autoantibody measurement in subjects to allow early diagnosis of autoimmune T1D.

Skin Autofluorescence Reflects Integration of Past Long-Term Glycemic Control in Patients With Type 1 Diabetes

OBJECTIVE The aim was to investigate the relationships between skin autofluorescence (AF) and the impact of past glycemic control and microvascular complications in Japanese patients with type 1 diabetes. RESEARCH DESIGN AND METHODS Two hundred forty-one patients and 110 controls were enrolled. Advanced glycation end product accumulation was measured with AF reader. Three monthly HbA1c levels during the past 20 years were determined from medical records, and the HbA1c area under the curve (AUC) was calculated. We performed multivariate regression analyses to examine the associations between the severity of diabetes complications and various variables. RESULTS Skin AF values increased with increasing the severity of retinopathy (P < 10−11, linear regression analysis) and nephropathy (P < 10−5 for chronic kidney disease stage; P < 10−5 for albuminuria-based stage). HbA1c AUC values over the past 15 years were significantly correlated with skin AF values (past 5 years: R = 0.35, P < 0.0001; past 10 years: R = 0.36, P < 0.0001; past 15 years: R = 0.55, P < 0.0001; past 20 years: R = 0.22, P = 0.13). HbA1c AUC values over the past 3, 5, 10, and 15 years were significantly associated with the severity of both nephropathy and retinopathy. Multivariate analyses in which HbA1c AUC value was removed from the independent variables indicated that only skin AF was independently associated with nephropathy, whereas age at registration, age at onset of diabetes, and skin AF were independently associated with retinopathy. CONCLUSIONS Skin AF reflects past long-term glycemic control and may serve as a surrogate marker for the development of microvascular complications in place of HbA1c AUC value.

Endogenous secretory receptor for advanced glycation endproducts levels are correlated with serum pentosidine and CML in patients with type 1 diabetes.

Advanced glycation end products (AGEs) and receptor for AGE (RAGE)-mediated mechanism has been implicated in the pathogenesis of the vascular derangements.1–3 Yonekura et al recently identified a novel splice variant of RAGE that would serve as a decoy receptor, and named it endogenous secretory RAGE (esRAGE).4 esRAGE is secreted from expresser cells exemplified by vascular endothelial cells and is able to captures RAGE ligands extracellularly, thereby protecting cells from AGE-induced injury.4 Recently, we reported that type 1 diabetic patients with high serum esRAGE levels were resistant to developing early retinal complications than those with low esRAGE levels.5 Moreover, plasma esRAGE is found to be a novel biomarker and a potential protective factor in metabolic syndrome and atherosclerosis.6 It is thus expected that esRAGE plays a protective role in the development of diabetic vascular complications. The balance or imbalance between RAGE ligand and esRAGE levels may be a …

Assaying Soluble Forms of Receptor for Advanced Glycation End Products

In response: Yamagishi and Imaizumi speculate that kinetics and role of circulating total soluble form of receptor for advanced glycation endproducts (soluble receptor for AGE, sRAGE) may be different from those of endogenous secretory RAGE (esRAGE) in diabetes. They also suggest an alternative interpretation that serum sRAGE level may reflect tissue membrane form of RAGE expression. Currently, 2 different types of sandwich enzyme-linked immunosorbent assays (ELISAs) are commercially available and used for measurement of circulating soluble RAGE proteins: [1] esRAGE ELISA from B-Bridge Int. esRAGE is a splice variant form of RAGE lacking transmembrane domain and secreting into extracellular space and the circulation.1 Sakurai et al developed its specific detection system using a capture monoclonal antibody (Ab) recognizing RAGE-extracellular domain and a detection polyclonal Ab for the esRAGE-specific C-terminal 16 amino acid sequence.2 This ELISA system is not influenced by coexistence of …

AGE down-regulation of monocyte RAGE expression and its association with diabetic complications in type 1 diabetes

Advanced glycation end product (AGE) engagement of a cell surface receptor for AGE (RAGE) has been implicated in the development of diabetic complications. In this study, we determined the RAGE mRNA levels in monocytes from type 1 diabetic patients and analyzed their relationship with diabetic vascular complications. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that the monocyte expression of RAGE mRNA was significantly lower in patients with retinopathy than in those without retinopathy and was also significantly down-regulated in patients with nephropathy in comparison with those without nephropathy. Experiments with monocyte-enriched cultures revealed that RAGE mRNA and protein levels were down-regulated by the exposure to glyceraldehyde-derived AGE-the recently identified high-affinity RAGE ligand. Accordingly, we then assayed for the serum levels of glyceraldehyde-derived AGE as well as those of carboxymethyllysine (CML)-the known RAGE ligand and related them to the monocyte levels of RAGE mRNA. This screen revealed a negative correlation between the two parameters. The results thus suggest that the decrease in monocyte RAGE expression can be at least partly accounted for by the ligand engagement and may be a factor contributing to the development of diabetic vascular complications.

Genetic polymorphism of renin-angiotensin system is not associated with diabetic vascular complications in Japanese subjects with long-term insulin dependent diabetes mellitus

In a hospital cohort study, we examined whether or not ACE (Angiotensin-I converting enzyme) and AGT (Angiotensinogen) gene polymorphisms were associated with the development of nephropathy in long-term Japanese insulin-dependent diabetes mellitus (IDDM) patients with or without proliferative retinopathy, and whether or not the polymorphisms were associated with an arteriosclerotic family history in first degree relatives of the patients. A total of 201 patients with IDDM for more than 10 years and 159 patients with IDDM for more than 15 years were randomly selected in our hospital. All patients received uniform diabetes management and were divided into three groups, no nephropathy, incipient nephropathy and clinical nephropathy groups. There were no differences in clinical characteristics excluding urinary albumin to creatinine ratio and systolic blood pressure between the three groups. ACE I/D polymorphism was related to plasma ACE activity, but there were no associations between ACE I/D polymorphism and the development of diabetic nephropathy, nor was renal deterioration observed in patients with proliferative retinopathy even in those with a history of diabetes for more than 15 years. The AGT polymorphism did not have an additive effect on the association between ACE polymorphism and the development of diabetic nephropathy in patients with or without retinopathy. Development of diabetic nephropathy in the patients with or without proliferative retinopathy did not result in ACE or AGT polymorphisms. On the other hand, the ACE DD genotype was associated with a family history of ischemic heart disease in first degree relatives (X2 score = 9.04, P < 0.05). ACE and AGT gene polymorphisms may not play a role in the protective or accelerative effect against the development of diabetic nephropathy in the patients with or without proliferative retinopathy, but ACE gene polymorphism might be related to an arteriosclerotic family history in Japanese IDDM patients.

Zinc transporter 8 autoantibodies in fulminant, acute-onset, and slow-onset patients with type 1 diabetes

The aim of this study was to determine the prevalence and role of autoantibodies to zinc transporter 8 (ZnT8A) in three forms (fulminant, acute‐onset, and slow‐onset) of Japanese patients with type 1 diabetes.

Onset age-dependent variations of three islet specific autoantibodies in Japanese IDDM patients

The age related incidence rate of insulin-dependent diabetes mellitus shows a bimodal distribution, not only in Caucasians but also in Japanese. To evaluate the onset age-related autoimmune profile at presentation in insulin-dependent diabetes mellitus (IDDM), glutamic acid decarboxylase (GAD) autoantibody, islet cell antibody (ICA), and insulin autoantibody (IAA) were measured in 137 newly diagnosed Japanese IDDM patients with onset ages between 0-29 years. The prevalence of GAD autoantibody was significantly increased from the lowest (32%) in the 0-5 years onset age group to 75% in the 13-19 years onset age group (P < 0.05), whereas the IAA prevalence significantly decreased from the peak (48%) in the 6-12 years onset age group to 10% in the 20-29 years onset age group (P < 0.05). The ICA prevalence was increased from the lowest (32%) in the 0-5 years onset age group to the highest (53%) in the 20-29 years onset age group similar to that for the GAD autoantibody. Such results demonstrate that there was age-related autoimmune characteristics at presentation of IDDM in Japanese as well as in Caucasians.

The relationship between depressive symptoms and diabetic complications in elderly patients with diabetes: Analysis using the Diabetes Study from the Center of Tokyo Women's Medical University (DIACET)

AIMS To investigate the association between likelihood or severity of depression and symptoms associated with diabetic complications in elderly Japanese patients with diabetes. METHODS This single-center cross-sectional study included 4283 patients with diabetes, 65 years and older (mean age was 73 ± 6 years, 38.7% were women, 3.9% had type 1 diabetes). Participants completed a self-administered questionnaire including items on subjective symptoms associated with diabetic microangiopathy, frequency of clinical visits due to vascular diseases (heart diseases, stroke, or gangrene), hospitalization, and the Patient Health Questionnaire-9 (PHQ-9), a simple but reliable measure of depression. The associations between severity of depression and diabetic complications were examined using logistic regression analysis. RESULTS According to the PHQ-9 scores, patients were classified into the following 3 categories: 0-4 points (n=2975); 5-9 points (n=842); and 10 or more points (n=466). Higher PHQ-9 scores were associated with increased odds ratios for retinopathy, symptoms related to peripheral polyneuropathy and autonomic neuropathy, and end-stage renal disease requiring dialysis after adjustment for age, gender, smoking status, and HbA1c (all p<0.05). CONCLUSIONS Significant relationships were found between depression severity and chronic diabetic complications among elderly Japanese patients with diabetes.