ADMA (asymmetric dimethylarginine) and angiogenic potential in patients with type 2 diabetes and prediabetes

Advances and Perspectives in Relation to the Molecular Basis of Diabetic Retinopathy-A Review

Diabetes mellitus (DM) is a growing problem nowadays, and diabetic retinopathy (DR) is its predominant complication. Currently, DR diagnosis primarily relies on fundoscopic examination; however, novel biomarkers may facilitate that process and make it widely available. In this current review, we delve into the intricate roles of various factors and mechanisms in DR development, progression, prediction, and their association with therapeutic approaches linked to the underlying pathogenic pathways. Specifically, we focus on advanced glycation end products, vascular endothelial growth factor (VEGF), asymmetric dimethylarginine, endothelin-1, and the epigenetic regulation mediated by microRNAs (miRNAs) in the context of DR.

Role of ADMA in the pathogenesis of microvascular complications in type 2 diabetes mellitus

Diabetic microangiopathy is a typical and severe problem in diabetics, including diabetic retinopathy, diabetic nephropathy, diabetic neuropathy, and diabetic cardiomyopathy. Patients with type 2 diabetes and diabetic microvascular complications have significantly elevated levels of Asymmetric dimethylarginine (ADMA), which is an endogenous inhibitor of nitric oxide synthase (NOS). ADMA facilitates the occurrence and progression of microvascular complications in type 2 diabetes through its effects on endothelial cell function, oxidative stress damage, inflammation, and fibrosis. This paper reviews the association between ADMA and microvascular complications of diabetes and elucidates the underlying mechanisms by which ADMA contributes to these complications. It provides a new idea and method for the prevention and treatment of microvascular complications in type 2 diabetes.

Functional AGXT2 SNP rs37369 Variant Is a Risk Factor for Diabetes Mellitus: Baseline Data From the Aidai Cohort Study in Japan

OBJECTIVES

The relationship between alanine-glyoxylate aminotransferase 2 (AGXT2) single-nucleotide polymorphisms (SNPs) and diabetes mellitus (DM) has not been investigated. Therefore, we performed a case-control study to examine this relationship.

METHODS

The study subjects included 2,390 Japanese men and women aged 34 to 88 years. In total, 190 cases were defined as having a fasting plasma glucose level ≥126 mg/dL, having a glycated hemoglobin ≥6.5% or currently using diabetic medication. The 2,200 remaining participants served as control subjects.

RESULTS

Compared with study subjects with the CC genotype of AGXT2 SNP rs37369, those with the TT, but not CT, genotype had a significantly increased risk of DM: the adjusted odds ratio (OR) for the TT genotype was 1.83 (95% confidence interval [CI], 1.04 to 3.47). AGXT2 SNPs rs37370 and rs180749 were not significantly associated with the risk of DM. The CTA haplotype of rs37370, rs37369 and rs180749 was significantly positively associated with the risk of DM (crude OR, 1.25; 95% CI, 1.01 to 1.56), whereas the CCA haplotype was significantly inversely related to DM (crude OR, 0.53; 95% CI, 0.27 to 0.95). The multiplicative interaction between AGXT2 SNP rs37369 and smoking status with regard to the risk of DM was not significant (p=0.32 for interaction).

CONCLUSIONS

This is the first study to show significant associations between AGXT2 SNP rs37369, the CTA haplotype, and the CCA haplotype and DM. No interaction with regard to the risk of DM was observed between rs37369 and smoking.

The impact of type 2 diabetes duration on serum asymmetric dimethylarginine and C-reactive protein concentration in Bosnian patients

Objective. The present study assessed the impact of type 2 diabetes mellitus (T2DM) duration on the serum asymmetric dimethylarginine (ADMA) and C-reactive protein (CRP) concentration in Bosnian patients.

Methods. Participants for this cross-sectional study were randomly selected from the Family Medicine Clinic (Sarajevo, Bosnia and Herzegovina). Serum ADMA concentration was determined by ELISA. Serum high-sensitivity (hs-CRP) was determined by particle-enhanced immunonephelometry. ANOVA test followed by Scheffe post-hoc test or Kruskal-Wallis test followed by Man-Whitney test were used for statistical analysis.

Results. The study included 38 patients in up to 10 years diabetes duration (≤10 years T2DM) group, 22 patients in greater than 10 years diabetes duration (>10 years T2DM) group, and 60 controls. Serum ADMA concentration in the >10 years T2DM group (1.81±0.15 μmol/L) was significantly higher compared to serum ADMA concentration in the ≤10 years T2DM group (1.38±0.41 μmol/L; p<0.001) and in controls (0.62±0.15 μmol/L; p<0.001). A significant difference in serum ADMA concentration was found between the <10 years T2DM group and the controls (p<0.001). The serum CRP concentration in the >10 years T2DM group [5.95 (4.20–9.12) mg/L] was significantly higher compared to serum CRP concentration in the <10 years T2DM group [2.35 (1.40–4.30) mg/L; p<0.001] and controls [0.85 (0.50–1.30) mg/L; p<0.001]. Significant difference in serum CRP concentration was observed between the <10 years T2DM group and controls (p<0.001).

Conclusions. The present study showed an increase in the serum ADMA and CRP concentrations with the advancement of T2DM. These results suggest that ADMA and CRP may serve as indicators of endothelial dysfunction and chronic low-grade inflammation progression in patients with T2DM. Larger prospective studies are required to confirm the observed findings.

Oxidative Stress and Arginine/Nitric Oxide Pathway in Red Blood Cells Derived from Patients with Prediabetes

The effects of the oral glucose tolerance test (OGTT) on red blood cells (RBCs) have not been thoroughly investigated, although it is known that the ingestion of 75 g of glucose during OGTT results in a systemic state of inflammation and oxidative stress. Therefore, we evaluated the effect of OGTT on oxidative stress and L-arginine/Nitric Oxide (L-Arg/NO) metabolic pathway in RBCs obtained from patients with prediabetes. Blood samples were collected from all participants before (T0) and at 10 (T1), 20 (T2), 30 (T3), 60 (T4), 90 (T5), 120 (T6), 150 (T7), and 180 (T8) minutes after glucose loading. Results showed a significant increase in oxidative stress status characterized by a rise in the GSSG/GSH ratio at T4 and T6 that increased in parallel with a reduction of NO production in RBCs. In addition, in this time frame, increased exposure of phosphatidylserine on RBCs membrane was observed. These metabolic modifications were rescued at T8, together with an increase in activated RBC NO synthase expression. These findings provide a possible explanation of the phenomena occurring after glucose loading and suggest that, even in the early stages of diabetes, it may be important to avoid acute variations in glycemia in order to prevent diabetic complications.