Molecular Mechanisms Responsible for Diastolic Dysfunction in Diabetes Mellitus Patients.

In diabetic patients, cardiomyopathy is an important cause of heart failure, but its pathophysiology has not been completely understood thus far. Myocardial hypertrophy and diastolic dysfunction have been considered the hallmarks of diabetic cardiomyopathy (DCM), while systolic function is affected in the latter stages of the disease. In this article we propose the potential pathophysiological mechanisms responsible for myocardial hypertrophy and increased myocardial stiffness leading to diastolic dysfunction in this specific entity. According to our model, increased myocardial stiffness results from both cellular and extracellular matrix stiffness as well as cell⁻matrix interactions. Increased intrinsic cardiomyocyte stiffness is probably the most important contributor to myocardial stiffness. It results from the impairment in cardiomyocyte cytoskeleton. Several other mechanisms, specifically affected by diabetes, seem to also be significantly involved in myocardial stiffening, i.e., impairment in the myocardial nitric oxide (NO) pathway, coronary microvascular dysfunction, increased inflammation and oxidative stress, and myocardial sodium glucose cotransporter-2 (SGLT-2)-mediated effects. Better understanding of the complex pathophysiology of DCM suggests the possible value of drugs targeting the listed mechanisms. Antidiabetic drugs, NO-stimulating agents, anti-inflammatory agents, and SGLT-2 inhibitors are emerging as potential treatment options for DCM.

C-reactive protein as a marker of progression of carotid atherosclerosis in subjects with type 2 diabetes mellitus.

BACKGROUND: This prospective study was designed to evaluate the effect of inflammatory markers on the presence and progression of subclinical markers of carotid atherosclerosis in a 3.8-year follow-up period in patients with type 2 diabetes mellitus (T2DM). PATIENTS AND METHODS: A total of 595 subjects with T2DM were enrolled. Subclinical markers of carotid atherosclerosis (carotid intima media thickness (CIMT), plaque thickness, and plaques presence) were assessed with ultrasound at the time of recruitment and again after 3.8 years. Subjects with T2DM were divided into 2 groups according to the plasma high sensitive C-reactive protein (hs-CRP) levels (subjects with hs-CRP ≥ 2 mg/L and subjects with hs-CRP below 2 mg/L). RESULTS: Subjects with T2DM and hs-CRP levels ≥ 2 mg/L had higher CIMT in comparison with subjects with T2DM and hs-CRP levels below 2 mg/L, and higher incidence of plaques/unstable plaques in comparison with subjects with T2DM and hs-CRP levels below 2 mg/L. Multivariate logistic regression analysis found the association between the HDL cholesterol level and presence of plaques, whereas the inflammatory marker hs-CRP was not associated with subclinical markers of progression of carotid atherosclerosis. Multiple linear regression analysis found the association between the hs-CRP levels and either CIMT progression rate or a change in the number of sites with plaques in a 3.8-year follow-up. CONCLUSIONS: We demonstrated an association between the inflammatory marker hs-CRP and either CIMT or incidence of plaques/unstable plaques at the time of recruitment in Caucasians with T2DM. Moreover, we found the association between hs-CRP levels and either CIMT progression rate or a change in the number of sites with plaques in a 3.8-year follow-up in subjects with T2DM.

Polymorphisms XbaI (rs693) and EcoRI (rs1042031) of the ApoB gene are associated with carotid plaques but not with carotid intima-media thickness in patients with diabetes mellitus type 2.

BACKGROUND: Apolipoprotein B is a key structural component of all the atherogenic lipoproteins (LDL, VLDL and IDL). Genetic variations of the ApoB gene may affect plasma ApoB and lipid levels, thus influencing atherogenesis. The present study was designed to investigate the association of polymorphisms XbaI (rs693) and EcoRI (rs1042031) of the ApoB gene with plasma ApoB level, lipid levels and the different ultrasound phenotypes of carotid atherosclerosis in patients with diabetes mellitus type 2. PATIENTS AND METHODS: 595 patients with diabetes (399 on statin therapy and 196 without) and 200 healthy controls were enrolled in the study. The carotid intima-media thickness (CIMT) and plaque characteristics (presence and structure) were assessed ultrasonographically. Biochemical analyses were performed using standard biochemical methods. Both XbaI (rs693) and EcoRI (rs1042031) genotypes were determined by real-time PCR. RESULTS: Genotype distributions and allele frequencies of the XbaI and EcoRI polymorphisms were not statistically significantly different between diabetic patients and controls. No statistically significant difference in lipid parameters, ApoA1, ApoB, hs-CRP and fibrinogen as well as CIMT was observed in diabetic patients regarding XbaI and EcoRI polymorphisms, even after adjustment for statin treatment. The risk of having plaques on carotid arteries was higher in homozygous carriers of the mutant X + allele (OR = 1.74, p = 0.03) and lower in diabetics carrying mutant E- alleles (OR = 0.48, p = 0.02). Neither XbaI nor EcoRI polymorphism was associated with CIMT or presence of unstable plaques in diabetic patients. Plasma ApoB level was not independently associated with any of the ultrasonographic parameters of carotid atherosclerosis. CONCLUSIONS: Both XbaI and EcoRI polymorphisms were associated with presence of plaques on carotid arteries but not with CIMT or presence of unstable plaques. Plasma ApoB level was not independently associated with ultrasonographic phenotypes of carotid atherosclerosis in patients with diabetes mellitus.

The a1/a2 polymorphism of the glycoprotein IIIa gene and myocardial infarction in Caucasians with type 2 diabetes.

A PlA1/A2 polymorphism of glycoprotein IIIa is known to be involved in the pathogenesis of coronary artery disease (CAD) and myocardial infarction (MI). The aim of this study was to investigate an association between the PlA1/A2 polymorphism of the glycoprotein IIIa gene and the risk of MI in Caucasians with type 2 diabetes. 549 Caucasians with type 2 diabetes were enrolled in the cross sectional retrospective case-control study: 224 patients with MI and 325 diabetic subjects without CAD. Blood biochemical analysis was performed. The polymerase chain reaction with restriction fragment length polymorphism was used for genetic analysis. Patients with MI were older (62 ± 11.8 vs. 58.5 ± 11.6 years; P < 0.001), and had a longer duration of type 2 diabetes (17.6 ± 8.9 vs. 15.1 ± 9.2; P = 0.01) compared to the diabetics without CAD. A significant difference in distribution of the A2A2 genotype of glycoprotein IIIa was not found between 224 diabetic patients with MI in comparison to 325 diabetics without CAD (11.6 vs. 14,1 %; n.s.). The diabetes duration and male sex were independent factors for the development of MI, whereas the PlA1/A2 polymorphism of glycoprotein IIIa was not. To conclude, The A2A2 genotype of the glycoprotein IIIa polymorphism was not associated with MI risk in Caucasians with type 2 diabetes.

Association of the C242T polymorphism in the NADPH oxidase p22 phox gene with carotid atherosclerosis in Slovenian patients with type 2 diabetes.

Oxidative stress plays an important role in the pathogenesis of diabetes and its complications. Genetic variations of enzymes producing reactive oxygen species could change their activity, thus contributing to the susceptibility to oxidative stress. The aim of this study was to examine the role of the NADPH oxidase C242T polymorphism in the development of carotid atherosclerosis in patients with type 2 diabetes. 286 diabetic patients and 150 healthy controls were enrolled in the study. Carotid atherosclerosis was quantified ultrasonographically as carotid intima-media thickness, plaque score (0-6) and plaque type (1-5). Diabetic patients were divided into low and high risk groups based on ultrasound phenotypes of carotid atherosclerosis. Genotypes were determined by real-time PCR. Levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) were measured by enzyme-linked immunosorbent assay (ELISA). Diabetic patients demonstrated a statistically significant difference compared to healthy controls in the following parameters: age, BMI, waist circumference, smoking prevalence, glucose, triglyceride and 8-OHdG serum levels. Control subjects had significantly higher levels of HDL, LDL and total cholesterol than diabetics (p < 0.001). The NADPH C242T polymorphism was not related with clinical characteristics, lipid parameters and 8-OHdG serum levels. We found no significant difference in the NADPH genotype distribution between diabetics and controls (p = 0.19) nor between low and high risk subgroups of diabetics (mean CIMT: p = 0.67; plaque score: p = 0.49, plaque type: p = 0.56). In the present study the NADPH C242T polymorphism was not associated with the degree of oxidative stress and carotid atherosclerosis. Further studies will show if it can be used as a genetic marker for carotid atherosclerosis in diabetic patients.

A1/A2 polymorphism of the glycoprotein IIIa gene and diabetic retinopathy in Caucasians with type 2 diabetes.

BACKGROUND: A PlA1/A2 polymorphism of glycoprotein IIIa is known to be involved in the pathogenesis of arterial thrombosis, myocardial infarction, stroke and type 2 diabetes, but there is no evidence of association with diabetic retinopathy. The aim of this study was to examine the role of the PlA1/A2 polymorphism of the glycoprotein IIIa gene in the development of diabetic retinopathy in Caucasians with type 2 diabetes. DESIGN: Cross-sectional case-control study. PARTICIPANTS: Totally 222 patients with diabetic retinopathy and 120 diabetic subjects without clinical signs of diabetic retinopathy from the Eye Clinic, University Medical Centre Ljubljana were enrolled in the study. METHODS: Fundus examination and blood biochemical analysis were performed. The polymerase chain reaction and restriction fragment length polymorphism were used. MAIN OUTCOME MEASURES: The total cholesterol, triglyceride, high-density lipoprotein levels, fasting blood glucose and HbA(1c) were measured, and the genotypes of the PlA1/A2 polymorphism were determined. RESULTS: Patients with diabetic retinopathy had earlier onset, longer duration of type 2 diabetes and a higher incidence of insulin therapy compared to the diabetic patients without diabetic retinopathy. A significantly lower frequency of the A2A2 genotype of glycoprotein IIIa was found in diabetic patients with retinopathy compared to those without retinopathy (odds ratio = 0.49, 95% confidence interval = 0.28-0.89; P = 0.018). CONCLUSIONS: The A2A2 genotype of the glycoprotein IIIa polymorphism was associated with lower risk for diabetic retinopathy in Caucasians with type 2 diabetes. Further studies are needed to elucidate its protective role in the development of diabetic retinopathy in Caucasians.

Phosphoprotein 1 (osteopontin) gene (rs4754) affects markers of subclinical atherosclerosis in patients with type 2 diabetes mellitus.

BACKGROUND: Our study was designed to test a possible association between polymorphisms of the SPP1 gene (rs4754, rs28357094) and markers of carotid atherosclerosis (CIMT, number of affected segments of carotid arteries, sum of plaque thickness, presence of carotid plaques, and presence of unstable carotid plaques) in subjects with T2DM. The second aim was to test the possible association between polymorphisms of the SPP1 gene (rs4754, rs28357094) and the progression of carotid atherosclerosis (CIMT progression, change in total plaque thickness, change in the number of sites with plaques) in subjects with T2DM. METHODS: In the prospective study 595 T2DM subjects were enrolled. Markers of carotid atherosclerosis were assessed ultrasonographically. rs4754 and rs28357094 polymorphisms of the phosphoprotein 1 (SPP1) gene were determined with real-time PCR. RESULTS: In our study we found an association between SPP1 rs4754 and the presence of plaques at the time of recruitment, whereas we did not find any association between SPP1 rs28357094 and subclinical markers of carotid atherosclerosis at the time of recruitment. Moreover, we did not find any statistically significant effect of either rs4754 or rs28357094 on subclinical markers of carotid atherosclerosis progression (CIMT progression, change in total plaque thickness, change in the number of sites with plaques). As shown by the multiple linear regression analysis, genotypes of either rs4754 or rs28357094 did not have a statistically significant effect on the progression of subclinical markers of carotid atherosclerosis (CIMT progression, change in total plaque thickness, change in the number of sites with plaques) after the adjustment for confounding variables. CONCLUSIONS: We demonstrated an important effect of the SPP1 rs4754 on subclinical markers of carotid atherosclerosis in subjects with T2DM; however, as demonstrated by the multiple linear regression analysis, neither rs4754 nor rs28357094 had an important impact on the progression of subclinical markers of carotid atherosclerosis in subjects with T2DM.

Association of manganese superoxide dismutase and glutathione S-transferases genotypes with myocardial infarction in patients with type 2 diabetes mellitus.

AIM: In the present study we investigated the association between genetic polymorphisms with functional effects on redox regulation: Val16Ala of manganese superoxide dismutase (MnSOD), polymorphic deletions of glutathione S-transferases M1 (GSTM1) and T1 (GSTT1) and Ile105Val of glutathione S-transferase P1 (GSTP1) and myocardial infarction (MI) in a group of patients with type 2 diabetes mellitus. METHODS: The study population consisted of 463 Caucasian subjects with type 2 diabetes mellitus of more than 10 years' duration: 206 patients with MI and 257 patients with no history of coronary artery disease (CAD). Genotypes were determined by polymerase chain reaction (PCR) with restriction fragment length polymorphism (RFLP) and with multiplex PCR. RESULTS: The genotype distributions of tested single nucleotide polymorphisms did not show significant difference between cases and controls. After adjustment for age, gender, smoking, BMI, duration of diabetes and lipid parameters carriers of GSTM1/GSTT1-null haplotype showed an increased risk for MI (OR=3.22, 95% CI 1.37-5.04, p=0.03). CONCLUSIONS: The GSTM1/GSTT1 haplotype might be a genetic risk factor for MI in patients with type 2 diabetes mellitus.