Gestational diabetes mellitus affects placental iron homeostasis: Mechanism and clinical implications.

Clinical studies suggest that pregnant women with elevated iron levels are more vulnerable to develop gestational diabetes mellitus (GDM), but the causes and underlying mechanisms are unknown. We hypothesized that hyperglycemia induces cellular stress responses leading to dysregulated placental iron homeostasis. Hence, we compared the expression of genes/proteins involved in iron homeostasis in placentae from GDM and healthy pregnancies (n = 11 each). RT-qPCR and LC-MS/MS analyses revealed differential regulation of iron transporters/receptors (DMT1/FPN1/ZIP8/TfR1), iron sensors (IRP1), iron regulators (HEPC), and iron oxidoreductases (HEPH/Zp). To identify the underlying mechanisms, we adapted BeWo trophoblast cells to normoglycemic (N), hyperglycemic (H), and hyperglycemic-hyperlipidemic (HL) conditions and assessed Fe3+ -uptake, expression patterns, and cellular pathways involving oxidative stress (OS), ER-stress, and autophagy. H and HL induced alterations in cellular morphology, differential iron transporter expression, and reduced Fe3+ -uptake confirming the impact of hyperglycemia on iron transport observed in GDM patients. Pathway analysis and rescue experiments indicated that dysregulated OS and disturbed autophagy processes contribute to the reduced placental iron transport under hyperglycemic conditions. These adaptations could represent a protective mechanism preventing the oxidative damage for both fetus and placenta caused by highly oxidative iron. In pregnancies with risk for GDM, antioxidant treatment, and controlled iron supplementation could help to balance placental OS levels protecting mother and fetus from impaired iron homeostasis.

Higher concentrations of osteoprotegerin in type 1 diabetic patients are related to retinopathy: Results from the Poznan Prospective Study.

BACKGROUND: Osteoprotegerin (OPG) is an arterial calcification marker which has been associated with vascular damage. Elevated OPG concentrations associated with low-grade inflammatory processes are found in diabetic subjects. OBJECTIVES: The aim of the study was to assess concentrations of OPG in relation to the presence of diabetic complications in patients with diabetes type 1 (DM 1) participating in the Poznan Prospective Study (PoProStu). MATERIAL AND METHODS: The study included 74 patients with DM1 (48 men) with a median age of 39 years (interquartile range [IQR]: 34-43) and a median 15-year history (IQR: 14-16) of diabetes, who were participants in the PoProStu. Serum OPG concentration was measured using the ELISA method, and serum concentration of C-reactive protein was measured with a high sensitivity test (hsCRP). The visceral adipose index (VAI) was used to determine indirect markers of insulin resistance (IR). The prevalence of microangiopathic diabetes complications was assessed. RESULTS: Retinopathy was diagnosed in 28 patients (38%), diabetic kidney disease (DKD) in 28 (38%) patients, and neuropathy in 17 (23%) patients. The median OPG level was 43.8 (28.0-74.0) pg/mL. Patients with retinopathy had higher levels of OPG than those without retinopathy: 47.5 (35.0-88.0) vs 35.4 (24.7-69.4) pg/mL (p = 0.04). Positive correlations were observed between OPG concentration and hsCRP (Rs = 0.53; p < 0.001), HbA1c level (Rs = 0.36; p = 0.002), VAI (Rs = 0.23; p = 0.04) and waist circumference (Rs = 0.24; p = 0.04). CONCLUSIONS: Higher concentrations of osteoprotegerin in DM1 patients are related to the presence of retinopathy. The study results indicate that OPG might play a role in the pathogenesis of vascular complications in association with hyperglycemia and low-grade inflammatory processes.

[The impact of chromatin modification on the development of chronic complications in patients with diabetes]. / Wplyw modyfikacji struktury chromatyny na rozwój przewleklych powiklan cukrzycowych.

Diabetes is a chronic, metabolic disease. Over 347 million people worldwide have diabetes. Chronic complications (retinopathy, nephropathy or neuropathy) are the major dangerous outcome of this disease. Recent studies indicate a significant role of epigenetic regulation in the development of chronic complications in patients with diabetes. Hyperglycemia could cause abnormal regulation of the activity of enzymes participating in the post-translational histone modifications (PTHMs) and initiation of changes in patterns of DNA methylation. It leads to modification of chromatin structure. These epigenetic abnormalities result in changes in the expression of genes involved in development of chronic inflammation, such as NF-KAPPAB (nuclear factor kappaB gene), TNFα (tumor necrosis factor a gene), IL6 (interleukin 6 gene) or MCP1 (monocyte chemoattractant protein 1 gene). It enhances endothelial cell dysfunction, which plays an important role in development of chronic, diabetic complications. In addition, caused by hyperglycemia epigenetic modifications changes in structure of chromatin explains "metabolic memory", a phenomenon of presence of pathological pathways related to the prolonged hyperglycemia in the past, despite maintaining good metabolic control later on.

Association investigation of BACH2 rs3757247 and SOD2 rs4880 polymorphisms with the type 1 diabetes and diabetes long-term complications risk in the Polish population.

Genetic factors are indicated in the development of type 1 diabetes (DM1). Recently, nucleotide variants of BACH2 and SOD2 have been associated with this chronic condition. Therefore, the purpose of the present study was to investigate the contribution of BACH2 rs3757247 and SOD2 rs4880 (Ala16Val) polymorphisms to the risk of DM1 and diabetes long-term complications. Selected polymorphic variants of BACH2 and SOD2 were investigated in a group of 141 patients with DM1 and in a group of age, gender-matched healthy subjects (n=369) using a high-resolution melting curve method. There was no evidence for either allelic or genotypic association with the risk of DM1 and diabetes chronic complications for analysed polymorphisms. In addition, no interaction between BACH2 and SOD2 variants in the development of this condition was observed. However, the frequency of BACH2 rs3757247 AG and AA genotypes was statistically different between DM1 patients with retinopathy and healthy individuals (odds ratio, 2.455; 95% confidence interval, 0.999-6.035; P=0.044), but this result did not survive multiple testing corrections. The present study did not confirm the involvement of BACH2 rs3757247 and SOD2 rs4880 polymorphisms in the development of DM1 and diabetes long-term complications. Further studies in a larger population sample are required.

Skin autofluorescence is associated with carotid intima-media thickness, diabetic microangiopathy, and long-lasting metabolic control in type 1 diabetic patients. Results from Poznan Prospective Study.

AIMS: Our aim was to assess the association between skin autofluorescence (AF) related to advanced glycation end products (AGEs) accumulation and long-term metabolic control, microvascular complications and carotid intima-media thickness (IMT) in an observational cohort of type 1 diabetes (DM1). METHODS: The analysis included 77 patients with DM1 (28 women and 49 men) aged 38 (IQR: 34-41), diabetes duration 15 (14-17), participating in Poznan Prospective Study (PoProStu). Skin AF was measured with AGE Reader (DiagnOptics). RESULTS: We found 50% of any microvascular complication; 37% of retinopathy, 37% of diabetic kidney disease and 22% of distal symmetrical neuropathy. Median carotid IMT was 0.57 (0.52-0.67) mm and skin AF 2.2 (IQR: 1.9-2.6). We found positive correlation between skin AF and patients' age (r=0.31, p=0.006), mean HbA1c from the observation time (r=0.35, p=0.001) and IMT (r=0.39, p<0.001). In multivariate logistic regression presence of microvascular complications was independently associated with skin AF: for retinopathy (OR 3.49; 95% CI: 1.08-11.28, p=0.03), for diabetic kidney disease (OR 3.62; 95% CI: 1.16-11.28, p=0.02), for neuropathy (OR 5.01; 95% CI: 1.21-20.77, p=0.02) and for any microangiopathy (OR 3.13; 95% CI: 1.06-9.18, p=0.03). CONCLUSION: Skin AF is a reliable marker of past glycemic control of diabetes. Increased accumulation of AGEs is related to the presence of diabetic microangiopathy as well as subclinical macroangiopathy in patients with type 1.

Role of epigenetic mechanisms in the development of chronic complications of diabetes.

There is growing evidence that epigenetic regulation of gene expression including post-translational histone modifications (PTHMs), DNA methylation and microRNA (miRNA)-regulation of mRNA translation could play a crucial role in the development of chronic, diabetic complications. Hyperglycemia can induce an abnormal action of PTHMs and DNA methyltransferases as well as alter the levels of numerous miRNAs in endothelial cells, vascular smooth muscle cells, cardiomyocytes, retina, and renal cells. These epigenetic abnormalities result in changes in the expression of numerous genes contributing to effects such as development of chronic inflammation, impaired clearance of reactive oxygen species (ROS), endothelial cell dysfunction and/or the accumulation of extracellular matrix in the kidney, which causing the development of retinopathy, nephropathy or cardiomyopathy. Some epigenetic modifications, for example PTHMs and DNA methylation, become irreversible over time. Therefore, these processes have gained much attention in explaining the long-lasting detrimental consequences of hyperglycaemia causing the development of chronic complications even after improved glycaemic control is achieved. Our review suggests that the treatment of chronic complications should focus on erasing metabolic memory by targeting chromatin modification enzymes and by restoring miRNA levels.

Expression of mitochondrial superoxide dismutase in polymorphonuclear leukocytes from patients with type 1 diabetes with and without microvascular complications.

INTRODUCTION: One of the causes of impaired antioxidant response in patients with type 1 diabetes might be decreased expression of mitochondrial manganese superoxide dismutase (MnSOD). OBJECTIVES: The aim of this study was to evaluate the expression of MnSOD on transcript and protein levels in polymorphonuclear leukocytes (PMNLs) from patients with type 1 diabetes and analyze its association with microvascular complications. PATIENTS AND METHODS: The MnSOD expression was assessed in PMNLs from 46 patients with type 1 diabetes and 12 age- and sex -matched healthy subjects. The study group was divided into 2 subgroups: with and without microvascular complications. The MnSOD expression on the transcript level was evaluated by real -time quantitative polymerase chain reaction, while that on the protein level by Western blot analysis. RESULTS: A significant increase in the MnSOD transcript level was observed in all patients with diabetes with and without microvascular complications (P = 0.01, P = 0.02, respectively). The MnSOD protein level was higher in patients without microvascular complications compared with those with complications and the control group (P = 0.05, P = 0.03, respectively). The MnSOD expression was positively correlated with fasting plasma glucose and total cholesterol levels both at the transcript level (r = 0.4, P <0.05 for both correlations) and at the protein level (r = 0.3 and r = 0.4, respectively, P <0.05). CONCLUSIONS: Although an increased MnSOD transcript level in patients with type 1 diabetes suggests enhanced antioxidant mobilization in all diabetic patients, decreased levels of the MnSOD protein in PMNLs from patients with microvascular complications compared with those without complications indicates that patients with microvascular complications may have impaired antioxidant response.

Association between IL-6 concentration and diabetes-related variables in DM1 patients with and without microvascular complications.

Interleukin 6 (IL-6) plays an important role in the initiation and acceleration of chronic inflammation and could contribute to development of microvascular complications in patients with type 1 diabetes (DM1). Therefore, this study was aimed to investigate the association between concentration of IL-6 in relation to glucose control, lipid profile, and body mass index (BMI) in 69 DM1 patients subdivided according to the absence or presence of microvascular complications. BMI, level of fasting plasma glucose (FPG), and concentrations of total cholesterol (TCH), LDL cholesterol (LDL-C), and IL-6 were higher in DM1 patients compared to the control group. In DM1 patients, IL-6 concentration was positively correlated with level of FPG, LDL-C, TCH concentrations, and BMI. These correlations were stronger in the subgroup of patients with microvascular complications. In addition, BMI independently influences IL-6 concentration in DM1 patients. In conclusion, elevated IL-6 concentration is associated with diabetes-related variables which could accelerate progression of microvascular complications in DM1 patients.

Does oxidized LDL contribute to atherosclerotic plaque formation and microvascular complications in patients with type 1 diabetes?

OBJECTIVE: The aim of the study was to investigate whether changes in the level of oxidized LDL (oxLDL) over 2-years contribute to the development of subclinical macroangiopathy and/or microvascular complications in patients with DM1. DESIGN AND METHODS: Basic clinical and biochemical parameters and oxLDL level were measured in 70 patients at baseline and after 2 years of the study. In addition, an ultrasonographic study was performed to assess the carotid intima media thickness (IMT). RESULTS: Patients did not differ according to basic clinical and biochemical parameters at the beginning and after 2 years of the study. IMT increased (p=0.000001) whereas oxLDL level decreased (p=0.00001) in DM1 patients during 2 years. Multivariate regression analysis showed that oxLDL independently influences IMT in DM1 patients (ß=0.454, R2=0.35). Further, positive correlations between oxLDL value and LDL-C concentration (r=0.585, p<0.05, n=70) and between oxLDL level and apo-B concentration have been established (r=0.610, p<0.05, n=70). Moreover, patients with chronic microvascular complications showed a higher value of IMT in comparison with patients without them (p=0.003). CONCLUSION: Our results provide the evidence that oxLDL accelerates atherosclerotic plaque formation and may contribute to the development of microvascular complications in DM1.

Evaluation of paraoxonase 1 arylesterase activity and lipid peroxide levels in patients with type 1 diabetes.

INTRODUCTION: Poor metabolic control of type 1 diabetes is one of the most important factors accelerating the development of late diabetic complications. Several other factors that might contribute to this process are currently being investigated. Low paraoxonase 1 (PON1) activity and high lipid peroxide (LPO) levels contribute to endothelial damage, but it remains unclear whether they are critical for the development of late diabetic complications. OBJECTIVES: The aim of the study was to evaluate PON1 arylesterase activity and LPO levels in patients with type 1 diabetes and to investigate whether these parameters are associated with metabolic control and late complications. Moreover, we aimed to establish whether PON1 activity and LPO levels differ between women and men with type 1 diabetes. PATIENTS AND METHODS: The study involved 80 patients with type 1 diabetes and 24 healthy subjects. PON1 activity was measured by a spectrophotometric method. LPO levels were measured by a commercial assay kit. RESULTS: Diabetic patients had lower PON1 activity and higher LPO levels than healthy people. We observed a negative correlation between PON1 activity and LPO levels in diabetic patients. There was no association between PON1 activity or LPO levels and metabolic parameters or late diabetic complications. There was a positive correlation between LPO levels and the body mass index (BMI) in women with type 1 diabetes. CONCLUSIONS: Our study showed that low PON1 activity and high LPO levels are not the most critical factors involved in late diabetic complications in type 1 diabetes. Increased LPO levels in women with type 1 diabetes may result from enhanced lipogenesis in this subgroup compared with diabetic men.

The relationship between concentrations of magnesium and oxidized low density lipoprotein and the activity of platelet activating factor acetylhydrolase in the serum of patients with type 1 diabetes.

The study was aimed at comparing the concentration of metabolic parameters, the serum concentration of oxidized low density lipoproteins (oxLDL) and the activity of platelet activating factor acetylhydrolase (PAF-AH) in the relation to the serum concentration of magnesium (Mg) in patients with type 1 diabetes (DM1). DM1 patients (n=78) were divided into 2 groups: patients with low serum Mg concentration (<0.7 mmol/L, group 1, n=34) and patients with reference levels of Mg (>or=0.7 mmol/L, group 2, n=44). A control group (n=24) of healthy subjects was also recruited. Our results showed that DM1 patients had lower serum Mg concentrations than the control group. It was found that parameters of poor metabolic control and lipid profile are not related to the serum Mg concentration in DM1 patients. However, both the Mg concentration and the PAF-AH activity are independently related to the serum oxLDL concentration. In group 1 the oxLDL concentration and the PAF-AH activity were higher than in group 2, and the control group. Two groups of DM1 patients did not show any differences with regard to the metabolic control. Therefore, the oxidative modification of LDL and the higher activity of PAF-AH are related with the low Mg status; however, no relation has been observed between these parameters and the poor metabolic control in DM1 patients.

The evaluation of IL-12 concentration, PAF-AH, and PLA(2) activity in patients with type 1 diabetes treated with intensive insulin therapy.

OBJECTIVES: The aim of the study was to evaluate the concentration of interleukin 12 (IL-12), the activity of phospholipase A(2) (PLA(2)), and platelet-activating factor acetylhydrolase (PAF-AH) in type 1 diabetes (DM1) patients treated with intensive insulin therapy. DESIGN AND METHODS: Studied parameters were measured in 81 patients, who were subdivided according to the HbA(1)c value, hsCRP concentration, and presence or absence of late complications. RESULTS: PAF-AH activity was higher in the DM1 patients versus the control group (P=0.042). IL-12 concentration was the highest in subgroup with > or =3 mg/L hsCRP (P<0.05). Negative correlations were found for the IL-12 and age of patients and for apo A-I in the subgroup with poor metabolic control. In addition, positive correlation for hsCRP and PAF-AH activity in the subgroup with > or =3 mg/L CRP (P<0.05) was also found. CONCLUSIONS: PAF-AH and IL-12 appear to be implicated in the development of a chronic inflammation in DM1. In addition, our results emphasize a protective role of apo A-I against an increase in IL-12 production.

IL-12 serum levels in patients with type 2 diabetes treated with sulphonylureas.

Interleukin-12 (IL-12) has been identified as a pro-inflammatory cytokine which is thought to contribute to the development of atherosclerosis. However, to date, the various associations between factors related to the course of type 2 diabetes, like metabolic compensation, beta cell secretory dysfunction, insulin resistance and IL-12 serum levels, remain unclear. Our study involved 41 patients with type 2 diabetes, 19 patients with coronary artery disease (CAD), and 19 healthy controls. We measured serum levels of fasting glucose, HbA(1)c, 1,5-anhydro-d-glucitol, and lipids. In addition, serum levels of C-peptide, insulin, proinsulin and IL-12 were assayed. HOMA(IR) score was calculated. The serum concentrations of IL-12 were higher in diabetics than in either patients with CAD or healthy controls, and were correlated with BMI, C-peptide, insulin, HOMA(IR), proinsulin and HDL serum levels. Multiple regression analysis revealed that the IL-12 serum level in type 2 diabetics primarily is dependent upon fasting proinsulin concentration. Our results demonstrate that elevated IL-12 serum levels in type 2 diabetics treated with sulphonylureas are induced especially by peripheral insulin resistance and beta cells dysfunction, as expressed by fasting serum proinsulin levels. This finding gives us hope that treatment to decrease peripheral insulin resistance and to avoid excessive proinsulin secretion might be successful in the prevention of IL-12-induced atherosclerosis.