Relation of asymmetrical dimethylarginine levels with renal outcomes in hypertensive patients with and without type 2 diabetes mellitus

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.

Nitric Oxide Synthesis Metabolites-As Potential Markers in Chronic Kidney Disease in Children

Nitric oxide (NO) is an important signaling molecule for many physiological and pathological processes. Diseases associated with abnormal NO synthesis include cardiovascular diseases, insulin-dependent diabetes, or chronic kidney disease (CKD). The aim of the paper was to evaluate NO synthesis metabolites, i.e., asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), dimethylamine (DMA), arginine, citrulline in plasma of patients with different severity of CKD and to seek possible links between these parameters and the development of this disease. Forty-eight CKD children and thirty-three age-matched controls were examined. Patients were divided into groups depending on the CKD stages (Group II-stage II, Group III-stage III, Group IV-stage IV, and Group RRT children on dialysis). To determine the concentrations of the above-mentioned metabolites in plasma liquid chromatography-mass spectrometry was used. There were significant differences observed in levels of ADMA, SDMA, DMA, and citrulline between control vis CKD groups (p values ranging from <0.001 to 0.029). Plasma arginine concentration was also higher in CKD patients compared to the control group but statistically insignificant. ADMA levels in CKD children were statistically significantly higher in relation to particular stages of CKD (RRT vis II stage of CKD: p = 0.01; RRT vis III-IV stages of CKD: p < 0.046). Citrulline levels in CKD children were statistically significantly higher in RRT group vis control (p < 0.001). Children with CKD develop disturbances in most metabolites of NO synthesis. Dialysis children treated show the greatest disturbances of plasma ADMA and citrulline levels. ADMA seems to be a good indicator of the gradual progression of the CKD, which is proved by the negative correlation with eGFR.

Scoring model to predict risk of chronic kidney disease in Chinese health screening examinees with type 2 diabetes

PURPOSE

As health screening continues to increase in China, there is an opportunity to integrate a large number of demographic as well as subjective and objective clinical data into risk prediction modeling. The aim of this study was to develop and validate a prediction model for chronic kidney disease (CKD) in Chinese health screening examinees with type 2 diabetes mellitus (T2DM).

METHODS

We conducted a retrospective cohort study consisting of 2051 Chinese T2DM patients between 35 and 78 years old who were enrolled in the XY3CKD Follow-up Program between 2009 and 2010. All participants were randomly assigned into a derivation set or a validation set at a 2:1 ratio. Cox proportional hazards regression model was selected for the analysis of risk factors for the development of the proposed risk model of CKD. We established a prediction model with a scoring system following the steps proposed by the Framingham Heart Study.

RESULTS

The mean follow-up was 8.52 years, with a total of 315 (23.20%) and 189 (27.27%) incident CKD cases in the derivation set and validation set, respectively. We identified the following risk factors: age, gender, body mass index, duration of type 2 diabetes, variation of fasting blood glucose, stroke, and hypertension. The points were summed to obtain individual scores (from 0 to 15). The areas under the curve of 3-, 5- and 10-year CKD risks were 0.843, 0.799 and 0.780 in the derivation set and 0.871, 0.803 and 0.785 in the validation set, respectively.

CONCLUSIONS

The proposed scoring system is a promising tool for further application of assisting Chinese medical staff for early prevention of T2DM complications among health screening examinees.

Anti-Inflammatory, Antioxidant, and Anti-Atherosclerotic Effects of Natural Supplements on Patients with FMF-Related AA Amyloidosis: A Non-Randomized 24-Week Open-Label Interventional Study

We aimed to evaluate the effect of a combination of natural products on parameters related to inflammation, endothelial dysfunction, and oxidative stress in a cohort of familial Mediterranean fever (FMF) patients with Serum Amyloid A amyloidosis, in a non-randomized, 24-week open-label interventional study. Morinda citrifolia (anti-atherosclerotic-AAL), omega-3 (anti-inflammatory-AIC), and extract with Alaskan blueberry (antioxidant-AOL) were given to patients with FMF-related biopsy-proven AA amyloidosis. Patients were >18 years and had proteinuria (>3500 mg/day) but a normal estimated glomerular filtration rate (eGFR). Arterial flow-mediated dilatation (FMD), carotid intima media thickness (CIMT), and serum biomarkers asymmetric dimethylarginine (ADMA), high sensitivity C-reactive protein (hs-CRP), pentraxin (PTX3), malondialdehyde (MDA), Cu/Zn-superoxide dismutase (Cu/Zn-SOD), and glutathione peroxidase (GSH-Px) were studied at baseline and after 24 weeks of treatment. A total of 67 FMF-related amyloidosis patients (52 male (77.6%); median age 36 years (range 21−66)) were enrolled. At the end of a 24-week treatment period with AAL, AIC, and AOL combination therapy, ADMA, MDA, PTX3, hsCRP, cholesterol, and proteinuria were significantly decreased compared to baseline, while CuZn-SOD, GSH-Px, and FMD levels were significantly increased. Changes in inflammatory markers PTX3, and hsCRP were negatively correlated with FMD change, and positively correlated with decreases in proteinuria, ADMA, MDA, cholesterol, and CIMT. Treatment with AAL, AIC and AOL combination for 24 weeks were significantly associated with reduction in inflammatory markers, improved endothelial functions, and oxidative state. Efficient control of these three mechanisms can have long term cardiovascular and renal benefits for patients with AA amyloidosis.

New Potential Biomarkers for Chronic Kidney Disease Management-A Review of the Literature

The prevalence of chronic kidney disease (CKD) is increasing worldwide, and the mortality rate continues to be unacceptably high. The biomarkers currently used in clinical practice are considered relevant when there is already significant renal impairment compromising the early use of potentially successful therapeutic interventions. More sensitive and specific biomarkers to detect CKD earlier on and improve patients' prognoses are an important unmet medical need. The aim of this review is to summarize the recent literature on new promising early CKD biomarkers of renal function, tubular lesions, endothelial dysfunction and inflammation, and on the auspicious findings from metabolomic studies in this field. Most of the studied biomarkers require further validation in large studies and in a broad range of populations in order to be implemented into routine CKD management. A panel of biomarkers, including earlier biomarkers of renal damage, seems to be a reasonable approach to be applied in clinical practice to allow earlier diagnosis and better disease characterization based on the underlying etiologic process.

Specific Lowering of Asymmetric Dimethylarginine by Pharmacological Dimethylarginine Dimethylaminohydrolase Improves Endothelial Function, Reduces Blood Pressure and Ischemia-Reperfusion Injury

Multiple clinical and preclinical studies have demonstrated that plasma levels of asymmetric dimethylarginine (ADMA) are strongly associated with hypertension, diabetes, and cardiovascular and renal disease. Genetic studies in rodents have provided evidence that ADMA metabolizing dimethylarginine dimethylaminohydrolase (DDAH)-1 plays a role in hypertension and cardiovascular disease. However, it remains to be established whether ADMA is a bystander, biomarker, or sufficient contributor to the pathogenesis of hypertension and cardiovascular and renal disease. The goal of the present investigation was to develop a pharmacological molecule to specifically lower ADMA and determine the physiologic consequences of ADMA lowering in animal models. Further, we sought to determine whether ADMA lowering will produce therapeutic benefits in vascular disease in which high ADMA levels are produced. A novel long-acting recombinant DDAH (M-DDAH) was produced by post-translational modification, which effectively lowered ADMA in vitro and in vivo. Treatment with M-DDAH improved endothelial function as measured by increase in cGMP and in vitro angiogenesis. In a rat model of hypertension, M-DDAH significantly reduced blood pressure (vehicle: 187 ± 19 mm Hg vs. M-DDAH: 157 ± 23 mm Hg; P < 0.05). Similarly, in a rat model of ischemia-reperfusion injury, M-DDAH significantly improved renal function as measured by reduction in serum creatinine (vehicle: 3.14 ± 0.74 mg/dl vs. M-DDAH: 1.1 ± 0.75 mg/dl; P < 0.01), inflammation, and injured tubules (vehicle: 73.1 ± 11.1% vs. M-DDAH: 22.1 ± 18.4%; P < 0.001). These pharmacological studies have provided direct evidence for a pathologic role of ADMA and the therapeutic benefits of ADMA lowering in preclinical models of endothelial dysfunction, hypertension, and ischemia-reperfusion injury. SIGNIFICANCE STATEMENT: High levels of ADMA occur in patients with cardiovascular and renal disease. A novel modified dimethylarginine dimethylaminohydrolase by PEGylation effectively lowers ADMA, improves endothelial function, reduces blood pressure and protects from ischemia-reperfusion renal injury.

Enhancing kidney DDAH-1 expression by adenovirus delivery reduces ADMA and ameliorates diabetic nephropathy

Endothelial dysfunction, characterized by reduced bioavailability of nitric oxide and increased oxidative stress, is a hallmark characteristic in diabetes and diabetic nephropathy (DN). High levels of asymmetric dimethylarginine (ADMA) are observed in several diseases including DN and are a strong prognostic marker for cardiovascular events in patients with diabetes and end-stage renal disease. ADMA, an endogenous endothelial nitric oxide synthase (NOS3) inhibitor, is selectively metabolized by dimethylarginine dimethylaminohydrolase (DDAH). Low DDAH levels have been associated with cardiac and renal dysfunction, but its effects on DN are unknown. We hypothesized that enhanced renal DDAH-1 expression would improve DN by reducing ADMA and restoring NOS3 levels. DBA/2J mice injected with multiple low doses of vehicle or streptozotocin were subsequently injected intrarenally with adenovirus expressing DDAH-1 (Ad-h-DDAH-1) or vector control [Ad-green fluorescent protein (GFP)], and mice were followed for 6 wk. Diabetes was associated with increased kidney ADMA and reduced kidney DDAH activity and DDAH-1 expression but had no effect on kidney DDAH-2 expression. Ad-GFP-treated diabetic mice showed significant increases in albuminuria, histological changes, glomerular macrophage recruitment, inflammatory cytokine and fibrotic markers, kidney ADMA levels, and urinary thiobarbituric acid reactive substances excretion as an indicator of oxidative stress, along with a significant reduction in kidney DDAH activity and kidney NOS3 mRNA compared with normal mice. In contrast, Ad-h-DDAH-1 treatment of diabetic mice reversed these effects. These data indicate, for the first time, that DDAH-1 mediates renal tissue protection in DN via the ADMA-NOS3-interaction. Enhanced renal DDAH-1 activity could be a novel therapeutic tool for treating patients with diabetes.

Association between estimated glomerular filtration rate (eGFR) and asymmetric dimethylarginine (ADMA) concentrations among the elderly in a rural community: a cross-sectional study

Background

Reduced glomerular filtration rate and increased asymmetric dimethylarginine (ADMA) are prevalent in elderly people. However, most of the studies that have examined the association between the two conditions were performed in patients with renal dysfunction, but not in the general elderly population. Thus, we investigated an association between estimated glomerular filtration rate (eGFR) and ADMA concentration among community-dwelling older Koreans.

Methods

A cross-sectional study was conducted on 269 men and 382 women (mean age, 71.6 years) enrolled in the Korean Social Life, Health, and Aging Project (KSHAP), a population-based cohort study of health determinants in elderly Koreans. We calculated eGFR using chronic kidney disease- Epidemiology Collaboration Group (CKD-EPI) equation. ADMA concentration was measured by an enzyme-linked immunosorbent assay. The association between eGFR and ADMA concentrations was analyzed by multiple linear regression models.

Results

The mean ADMA was significantly higher in people with eGFR< 60 mL/min/1.73m² (0.691 μmol/L) than in those with eGFR≥60 mL/min/1.73m² (0.667 μmol/L, p = 0.013). The negative correlations between eGFR level and ADMA concentrations were significant in men and women after adjusted age. After adjusting for potential confounders which were sex, age, body surface, blood pressure, total and HDL cholesterol, diabetes, smoking, and drinking, eGFR levels were inversely associated with ADMA concentrations both in men (β = − 0.0015, p = 0.005) and women (β = − 0.001, p = 0.039).

Conclusion

Our findings suggest that an inverse association exists between eGFR and ADMA concentrations among the Korean elderly in a rural community.

Blood and urine biomarkers in chronic kidney disease: An update

INTRODUCTION

Chronic kidney disease (CKD) is a silent disease. Most CKD patients are unaware of their condition during the early stages of the disease which poses a challenge for healthcare professionals to institute treatment or start prevention. The trouble with the diagnosis of CKD is that in most parts of the world, it is still diagnosed based on measurements of serum creatinine and corresponding calculations of eGFR. There are controversies with the current staging system, especially in the methodology to diagnose and prognosticate CKD.

OBJECTIVE

The aim of this review is to examine studies that focused on the different types of samples which may serve as a good and promising biomarker for early diagnosis of CKD or to detect rapidly declining renal function among CKD patient.

METHOD

The review of international literature was made on paper and electronic databases Nature, PubMed, Springer Link and Science Direct. The Scopus index was used to verify the scientific relevance of the papers. Publications were selected based on the inclusion and exclusion criteria.

RESULT

63 publications were found to be compatible with the study objectives. Several biomarkers of interest with different sample types were taken for comparison.

CONCLUSION

Biomarkers from urine samples yield more significant outcome as compare to biomarkers from blood samples. But, validation and confirmation with a different type of study designed on a larger population is needed. More comparison studies on different types of samples are needed to further illuminate which biomarker is the better tool for the diagnosis and prognosis of CKD.