ADMA is a correlate of insulin resistance in early-stage diabetes independent of hs-CRP and body adiposity

Crucial markers showing the risk of coronary artery disease in obesity: ADMA and neopterin

Background

Obesity is responsible for high morbidity and mortality, both in developed and developing countries. It is associated with many chronic and metabolic diseases. Asymmetric dimethylarginine (ADMA) has been demonstrated to be a biomarker of endothelial dysfunction in humans and increased ADMA associated with cardiovascular disease (CVD) risk has been reported in many states. Neopterin (NP) produced by monocytes/macrophages in response to stimulation by interferon-gamma (IFN-γ) is emphasized in recent findings. The current study aims to investigate ADMA and NP levels which may assume a role in guiding the early diagnosis of coronary artery disease in obesity.

Methods

This is an original research study in which ADMA and NP levels of 50 patients (25 male/25 female) diagnosed with obesity were compared with those of 30 healthy individuals (15 male/15 female) as control. The high-performance liquid chromatography (HPLC) method was used while determining parameters.

Results

ADMA and NP levels in obese individuals were found to be significantly higher than in those enrolled in the control. ADMA values were found to be higher in obese subjects (0.71±0.24 μmol/L) as compared with levels found in healthy subjects (0.58±0.16 μmol/L) (p<0.05). A significant increase of serum neopterin levels was found in obese subjects (8.8±3.5 μmol/L) as compared with controls (4.9±1.69 μmol/L) (p<0.05). Also, there was a strong positive correlation between NP and ADMA values in obese individuals (r=0.954).

Conclusions

Our study revealed that obese subjects have higher ADMA and neopterin levels. These results demonstrated that both ADMA and NP levels may be potential risk factors for coronary heart disease in obesity.

Asymmetrical dimethylarginine induces dysfunction of insulin signal transduction via endoplasmic reticulum stress in the liver of diabetic rats

AIMS

Endoplasmic reticulum stress (ERS) as an emerging factor is involved in insulin resistance (IR), which is the pathological basis of diabetes mellitus. Accumulation of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase is associated with IR, but the underlying mechanisms have not been elucidated. This study was to reveal the important role of ADMA in IR and determine whether endogenous ADMA accumulation contributes to hepatic IR via ERS in diabetic rats and hepatocytes.

MATERIALS AND METHODS

Diabetic rat model was induced by a single intraperitoneal injection of streptozotocin (50 mg/kg). Phosphorylation of insulin receptor substrate 1 (IRS1) and protein kinase B (Akt) was detected to evaluate IR. The protein kinase PKR-like ER kinase (PERK) and eukaryotic initiation factor 2α kinase (eIF2α) phosphorylation, x-box binding protein-1 (XBP-1) splicing, glucose-regulated protein 78 (GRP78) and C/EBP homologues protein (CHOP) expressions were measured to assess ERS.

KEY FINDINGS

Endogenous ADMA content was significantly increased and positively correlated with either IR as evidenced by increased IRS1 at serine and reduced Akt phosphorylation or ERS as indicated by upregulations of PERK and eIF2α phosphorylation, XBP-1 splicing, GRP78 and CHOP expressions in the liver of diabetic rats compared with control rats. Exogenous ADMA directly caused IR and ERS in dose- and time-dependent manners in primary mouse hepatocytes. Pretreatment with ERS inhibitor 4-phenylbutyrate or ADMA antagonist L-arginine not only improved ADMA-associated or -induced hepatic IR but also attenuated ADMA-associated or -induced ERS in diabetic rats or hepatocytes.

SIGNIFICANCE

These findings indicate that endogenous ADMA accumulation contributes to hepatic IR via ERS in diabetic rats.

Body Composition Indices and Cardiovascular Risk in Type 2 Diabetes. CV Biomarkers are not Related to Body Composition

Background

This study aims to explore the correlations of body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), waist-to-hip ratio (WHR) and body composition with levels of asymmetric dimethylarginine (ADMA), endothelin 1(ET-1), N-terminal brain natriuretic pro-peptide (NT-proBNP) and calculated cardiovascular risks.

Methods

102 women and 67 men with type 2 diabetes participated. Serum levels of NT-proBNP were measured by electro-hemi-luminescence while ELISA were used for ADMA and ET-1. Cardiovascular risks were calculated using the Framingham Risk Score (FRS), the UKPDS 2.0 and the ADVANCE risk engines. Statistical analysis was performed on an IBM SPSS 19.0.

Results

The BMI outperformed all other indices of obesity (WC, WHtR, WHR), as well as body composition parameters (body fat%, fat mass, fat free mass and total body water) in relation to the estimated risks for coronary heart disease and stroke, based on different calculators. The correlations of the obesity indices with the serum cardiovascular biomarkers were not significant except for BMI and fat mass versus ET-1, and for fat free mass and total body water versus ADMA.

Conclusions

The WC, WHR, WHtR, BF%, FM and FFM apparently do not add significant information related to the levels of cardiovascular biomarkers or the calculated CV-risks.

The effect of resveratrol supplementation on serum levels of asymmetric de-methyl-arginine and paraoxonase 1 activity in patients with type 2 diabetes: A randomized, double-blind controlled trial

The present study sought to investigate the effect of micronized resveratrol supplementation on serum levels of asymmetric de-methyl-arginine (ADMA) and paraoxonase-1 (PON1) activity in patients with type 2 diabetes (T2D). In this double-blinded randomized trial, 76 patients with T2D were recruited. Participants were randomly assigned to consume 1,000 mg resveratrol or placebo capsules (methylcellulose) per day, for 8 weeks. Serum levels of ADMA and PON1 enzyme activity were measured at the beginning and end of the intervention using the enzyme-linked immunosorbent assay method. In total, 71 participants completed the study. Our results showed that resveratrol significantly decreased serum levels of ADMA (-0.16 ± 0.11, p < .001) and improved PON1 enzyme activity (15.39 ± 13.99, p < .001) compared with placebo, after adjusting for confounding factors (age, sex, and baseline body mass index). Our findings suggest that 8-week resveratrol supplementation may produce beneficial effects on serum levels of ADMA and PON1 enzyme activity in patients with T2DM. However, further research is needed to confirm the veracity of these results.

Association of endothelial dysfunction with cardiovascular risk factors and new-onset diabetes mellitus in patients with hypertension

Asymmetric dimethylarginine (ADMA), which is the main endogenous inhibitor of nitric oxide synthase, plays a critical role in the process of endothelial dysfunction. The authors evaluated the association between high plasma ADMA levels in patients with hypertension and the presence of cardiovascular risk factors and the development of type 2 diabetes mellitus (DM) and cardiovascular outcomes, including death. The authors evaluated 191 patients with hypertension who were stratified into two groups according to the median value of basal ADMA: those with high levels of plasma ADMA (>0.55 μmol/L) and low levels of plasma ADMA (≤0.55 μmol/L) who were prospectively evaluated over 5.8 years. High ADMA levels were seen in patients with higher weight, body mass index, waist circumference, triglycerides, uric acid, and high-sensitivity C-reactive protein, and lower levels of high-density lipoprotein cholesterol and in patients with type 2 DM. There was an association between high plasma ADMA levels and the occurrence of cardiovascular death. In a subgroup of patients with hypertension free from metabolic syndrome and DM at baseline, there was an association between high ADMA levels and the development of type 2 DM. This study confirms the association of high plasma ADMA levels and the presence of cardiovascular risk factors in patients with hypertension and suggests a positive predictive value of high plasma ADMA levels for cardiovascular death in patients with hypertension and also for the development of type 2 DM in a subgroup of patients with hypertension free from metabolic abnormalities.

The role of increased glucose on neurovascular dysfunction in patients with the metabolic syndrome

Metabolic syndrome (MetS) causes autonomic alteration and vascular dysfunction. The authors investigated whether impaired fasting glucose (IFG) is the main cause of vascular dysfunction via elevated sympathetic tone in nondiabetic patients with MetS. Pulse wave velocity, muscle sympathetic nerve activity (MSNA), and forearm vascular resistance was measured in patients with MetS divided according to fasting glucose levels: (1) MetS+IFG (blood glucose ≥100 mg/dL) and (2) MetS-IFG (<100 mg/dL) compared with healthy controls. Patients with MetS+IFG had higher pulse wave velocity than patients with MetS-IFG and controls (median 8.0 [interquartile range, 7.2-8.6], 7.3 [interquartile range, 6.9-7.9], and 6.9 [interquartile range, 6.6-7.2] m/s, P=.001). Patients with MetS+IFG had higher MSNA than patients with MetS-IFG and controls, and patients with MetS-IFG had higher MSNA than controls (31±1, 26±1, and 19±1 bursts per minute; P<.001). Patients with MetS+IFG were similar to patients with MetS-IFG but had higher forearm vascular resistance than controls (P=.008). IFG was the only predictor variable of MSNA. MSNA was associated with pulse wave velocity (R=.39, P=.002) and forearm vascular resistance (R=.30, P=.034). In patients with MetS, increased plasma glucose levels leads to an adrenergic burden that can explain vascular dysfunction.

E-selectin and sICAM-1, biomarkers of endothelial function, predict recurrence of venous thromboembolism

BACKGROUND

Risk factors for atherosclerosis and venous thromboembolism (VTE) overlap and are mostly associated with endothelial dysfunction (ED). We hypothesized that ED is present in patients after the first episode of acute pulmonary embolism (APE) and predicts the risk of VTE recurrence.

DESIGN AND METHODS

Patients, at least 6months after the first episode of symptomatic, confirmed APE were included in this case-control study. The exclusion criteria were risk factors for cardiovascular diseases and other conditions associated with endothelial dysfunction. Eighty two patients (aged 38±11years; 44 M; 38 F) were enrolled in the study, 39 after provoked APE, 43 after unprovoked APE, and 30 controls (C) (aged 38±12years; 15 M, 15 F). In order to evaluate the endothelial function in patients with a history of APE flow-mediated dilation (FMD) of the brachial artery and biomarkers of endothelial dysfunction (sVCAM-1, sICAM-1, ADMA, E-selectin) were measured. Subsequently all patients were followed up in an outpatient clinic for VTE recurrence.

RESULTS

FMD was more often impaired in APE patients than in controls (5.3% (0.8-20.3) vs. 13.8% (4.1-24.3); p<0.0001). Biomarker levels differed between APE and C groups: sVCAM-1 (631ng/ml (105-2382) vs. 495ng/ml (348-934); p=0.04) and sICAM-1 (679ng/ml (279-1006) vs. 600ng/ml (394-766); p=0.002). There were 19 recurrences of VTE during the at least 12-month follow-up (15 with history of unprovoked-APE and 4 after provoked-APE). E-selectin ≥39ng/ml and sICAM-1≤655ng/ml indicated the group without recurrence of VTE. In a group of 43 unprovoked APE patients both E-selectin<39ng/ml and sICAM-1>655ng/ml were found in 17 subjects. Eleven of them (65%) were diagnosed with recurrent VTE.

CONCLUSIONS

Endothelial function is significantly impaired in patients after an episode of APE as indicated by FMD assessment and biomarker levels. Low concentrations of E-selectin and high levels of sICAM-1 are associated with a high risk of recurrent thromboembolism.

Atorvastatin modulates the DDAH1/ADMA system in high-fat diet-induced insulin-resistant rats with endothelial dysfunction

Dimethylarginine dimethyl-aminohydrolase 1 (DDAH1) is a metabolic enzyme for asymmetric dimethylarginine (ADMA), both of which are closely related to endothelial function. Endothelial dysfunction, a main risk factor of cardiovascular diseases, can be attributed to insulin resistance. We aimed to determine the effects of atorvastatin, an endothelium-protective drug, on DDAH1/ADMA in insulin-resistant rats. Insulin resistance in male Sprague-Dawley rats was induced with a high-fat diet for 8 weeks. Some rats received atorvastatin (30 mg/kg/day) for an additional 8 weeks. Insulin-resistant rats exhibited not only decreases in the DDAH activity and aortic expression of DDAH1 and sterol regulatory element-binding protein 1 (SREBP1) but also increases in plasma ADMA levels, all of which were inhibited by atorvastatin. Insulin sensitivity and DDAH activity showed a significant positive correlation. In conclusion, our results suggest that atorvastatin may modulate DDAH1/ADMA to improve endothelial function in insulin-resistant rats; SREBP1 may also play a role in this.

Improved blood pressure, nitric oxide and asymmetric dimethylarginine are independent after bariatric surgery

Background

Obesity is associated with hypertension, but the exact mechanism is not fully understood. Bariatric surgery significantly decreases weight and blood pressure (BP). Low plasma nitric oxide (NO) and raised asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO, concentrations are associated with both obesity and hypertension. Correlations between the changes in these parameters were studied after bariatric surgery.

Methods

Weight, BP, plasma ADMA and NO were measured in 29 obese patients (24 female, 5 male) before and six weeks after bariatric surgery.

Results

Patients were 39.2 ± 1.2 (mean ± SEM) years old and weighed 126 ± 3 kg. Six weeks after the surgery, patients had lost 10 ± 0.7 kg ( P < 0.0001) and mean arterial pressure (MAP) decreased by 11 ± 1.0 mmHg ( P < 0.0001). The plasma ADMA concentration decreased by 24 ± 2% from 5 ± 0.4 to 4.0 ± 0.3 μmol/L ( P < 0.0001). The plasma total nitrite concentration increased by 15 ± 1% from 51.4 ± 2.6 to 60 ± 3 μmol/L ( P < 0.0001). The correlation between the decrease of ADMA and increase of NO subsequent to weight loss was significant ( P < 0.0001). However, MAP was not correlated to the changes in ADMA or NO.

Conclusions

After bariatric surgery, beneficial changes in BP, NO and ADMA occur, but our findings suggest that these BP changes are independent of changes in the NO–ADMA axis. Other causes for the changes in BP should therefore be considered.

The dual behavior of heat shock protein 70 and asymmetric dimethylarginine in relation to serum CRP levels in type 2 diabetes

BACKGROUND

Experimental evidence suggests that heat shock proteins (HSP) and asymmetric dimethylarginine (ADMA) are induced in the state of chronic inflammation and stress conditions. They are both inhibitors of nitric oxide synthase (NOS). The aim of this study was to evaluate the correlation between ADMA and HSP70, in patients with type 2 diabetes with respect to serum levels of C reactive protein (CRP).

METHODS

We quantified serum HSP70, ADMA and CRP in 80 newly-diagnosed patients with type 2 diabetes plus 80 age-, sex and BMI-matched healthy controls. The patients and controls were also stratified into groups of high and low CRP levels (cut-point: 2.5mg/ml).

RESULTS

Patients with type 2 diabetes had significantly higher serum HSP70 (0.52 [0.51-0.66] vs. 0.27 [0.26-0.36], p<0.001), ADMA (0.86 [0.81-0.92] vs. 0.72 [0.71-0.85], p<0.05) and CRP (2.9 [1.7-3.4] vs. 1.6[1.2-2.3], p<0.05) compared with healthy controls. Serum HSP70 and ADMA levels were significantly correlated in patients with high CRP levels (r=0.89, p<0.01), whereas there were no correlation in patients with low CRP (r=-0.37, p=0.07) and controls. This correlation was significant (r=0.77, p<0.001) in patients with high CRP and also in patients with low CRP levels (r=-0.51, p<0.05), after multiple adjustments for LDL and HDL levels.

DISCUSSION

We showed that, in a state of high inflammation; serum levels of ADMA parallel the HSP70 levels. However in low inflammation, they are negatively correlated. The duality in HSP70 and ADMA correlation may be related to the duality of NOS function in low and high CRP levels.