Asymmetric dimethylarginine (ADMA) is associated with reduced myocardial mechano-energetic efficiency in hypertensive subjects

BACKGROUND AND AIMS

Our prior study showed that endothelial dysfunction contributed to reduced myocardial mechano-energetics efficiency (MEEi) independently of several confounders. Reduced activity of endothelial nitric oxide synthase may be due to increased levels of the endogenous inhibitor asymmetric dimethylarginine (ADMA). The impact of ADMA on myocardial MEEi has not been determined yet. This study aims to investigate the association between plasma ADMA levels and MEEi in drug-naïve hypertensive individuals.

METHODS AND RESULTS

63 hypertensive individuals participating in the CATAnzaro MEtabolic RIsk factors (CATAMERI) study were included. All participants underwent to an echocardiogram for myocardial MEEi measurement. ADMA plasma concentrations were measured by high-performance liquid chromatography. A multivariate linear regression analysis was conducted to investigate the independent association between ADMA levels and MEEi. In a univariate analysis, ADMA levels were significantly associated with myocardial MEEi (r = 0.438; P < 0.001). In a multivariate regression analysis, plasma ADMA levels were associated to decreased myocardial MEEi (β = 0.458, P < 0.001) independently of well-established cardiovascular risk factors including age, sex, BMI, waist circumference, smoking status, total cholesterol and HDL, triglycerides, glucose tolerance status, and HOMA-IR index of insulin resistance.

CONCLUSIONS

ADMA may contribute to reduced myocardial MEEi by reducing nitric oxide bioavailability.

Value of Serum Asymmetric Dimethylarginine (ADMA) As a Novel Biomarker for Uveitis in Behçet's Disease

PURPOSE

To evaluate the serum asymmetric dimethylarginine (ADMA) level as a biomarker for uveitis in Behçet's Disease (BD).

METHODS

In this cross-sectional study, two groups of BD patients were examined: 33 with uveitis and 27 without uveitis. All patients were clinically evaluated, with disease activity measured by Behçet's Disease Current Activity Form (BDCAF) score. They also underwent thorough ophthalmic evaluation, and routine laboratory investigations, including serum ADMA.

RESULTS

Patients with BD who experienced active or inactive uveitis had higher levels of serum ADMA compared to those without uveitis. Anterior (ρ = 0.34, p < 0.01), posterior (ρ = 0.3, p < 0.05), and pan uveitis (ρ = 0.35, p < 0.01) were significantly correlated with serum ADMA levels. However, there was no significant correlation between ADMA and other BD manifestations. ROC curve analysis showed that increased serum ADMA levels in BD patients predicted uveitis with a sensitivity of 61.8%, specificity of 96.2%, and AUC of 0.78(95% CI: 0.66-0.9, p < 0.001).

CONCLUSION

Serum ADMA level can serve as a novel biomarker of uveitis in BD and its severity with good diagnostic accuracy, regardless of its site or activity.

DDAH1 recruits peroxiredoxin 1 and sulfiredoxin 1 to preserve its activity and regulate intracellular redox homeostasis

Growing evidence suggests that dimethylarginine dimethylaminohydrolase 1 (DDAH1), a crucial enzyme for the degradation of asymmetric dimethylarginine (ADMA), is closely related to oxidative stress during the development of multiple diseases. However, the underlying mechanism by which DDAH1 regulates the intracellular redox state remains unclear. In the present study, DDAH1 was shown to interact with peroxiredoxin 1 (PRDX1) and sulfiredoxin 1 (SRXN1), and these interactions could be enhanced by oxidative stress. In HepG2 cells, H2O2-induced downregulation of DDAH1 and accumulation of ADMA were attenuated by overexpression of PRDX1 or SRXN1 but exacerbated by knockdown of PRDX1 or SRXN1. On the other hand, DDAH1 also maintained the expression of PRDX1 and SRXN1 in H2O2-treated cells. Furthermore, global knockout of Ddah1 (Ddah1-/-) or liver-specific knockout of Ddah1 (Ddah1HKO) exacerbated, while overexpression of DDAH1 alleviated liver dysfunction, hepatic oxidative stress and downregulation of PRDX1 and SRXN1 in CCl4-treated mice. Overexpression of liver PRDX1 improved liver function, attenuated hepatic oxidative stress and DDAH1 downregulation, and diminished the differences between wild type and Ddah1-/- mice after CCl4 treatment. Collectively, our results suggest that the regulatory effect of DDAH1 on cellular redox homeostasis under stress conditions is due, at least in part, to the interaction with PRDX1 and SRXN1.

Arginine metabolomics in mood disorders

Alterations of nitric oxide (NO) homeostasis have been described in mood disorders. However, the analytical challenges associated with the direct measurement of NO have prompted the search for alternative biomarkers of NO synthesis. We investigated the published evidence of the association between these alternative biomarkers and mood disorders (depressive disorder or bipolar disorder). Electronic databases were searched from inception to the June 30, 2023. In 20 studies, there was a trend towards significantly higher asymmetric dimethylarginine (ADMA) in mood disorders vs. controls (p = 0.072), and non-significant differences in arginine (p = 0.29), citrulline (p = 0.35), symmetric dimethylarginine (SDMA; p = 0.23), and ornithine (p = 0.42). In subgroup analyses, the SMD for ADMA was significant in bipolar disorder (p < 0.001) and European studies (p = 0.02), the SMDs for SDMA (p = 0.001) and citrulline (p = 0.038) in European studies, and the SMD for ornithine in bipolar disorder (p = 0.007), Asian (p = 0.001) and American studies (p = 0.005), and patients treated with antidepressants (p = 0.029). The abnormal concentrations of ADMA, SDMA, citrulline, and ornithine in subgroups of mood disorders, particularly bipolar disorder, warrant further research to unravel their pathophysiological role and identify novel treatments in this group (The protocol was registered in PROSPERO: CRD42023445962).

Asymmetric Dimethylarginine and NT-proBNP Levels Provide Synergistic Information in Pulmonary Arterial Hypertension

BACKGROUND

Plasma asymmetric dimethylarginine (ADMA) is elevated in pulmonary arterial hypertension (PAH) and is associated with unfavorable outcomes.

OBJECTIVES

The aim of this study was to assess changes in ADMA plasma levels for monitoring disease progression and outcomes during PAH-specific therapy.

METHODS

ADMA was measured at baseline and after at least 6 months of follow-up using enzyme-linked immunosorbent assay and high-performance liquid chromatography. Changes in ADMA were analyzed in relation to changes in established PAH markers, including hemodynamic status, N-terminal pro-brain natriuretic peptide (NT-proBNP) and risk assessment scores. Impact on survival was assessed using Kaplan-Meier curves and Cox proportional hazards models.

RESULTS

Between 2008 and 2019, ADMA samples were collected prospectively from 215 patients with PAH. Change in ADMA plasma level was a predictor of disease progression and survival. ΔADMA (median -0.03 μmol/L; 95% CI: -0.145 to 0.0135) was correlated with change in mean pulmonary arterial pressure (P < 0.005; rS = 0.287) but was not significantly correlated with ΔNT-proBNP (P = 0.056; rS = 0.135). Patients with decreased ADMA plasma levels at follow-up had better 3-year and 5-year survival rates (88% and 80%, respectively, vs 72% and 53% in those without decreases in ADMA) (P < 0.005; pulmonary hypertension-related mortality or lung transplantation). Patients with decreases in both ADMA and NT-proBNP had better survival rates compared with patients in whom only 1 parameter improved (P < 0.005). ΔADMA was a significant predictor of survival in Cox regression analysis and also when corrected for ΔNT-proBNP (HRs: 1.27 and 1.35, respectively; P < 0.005).

CONCLUSIONS

ADMA and NT-proBNP provide synergistic prognostic information for patients with PAH. ADMA could be used as an objective and distinct biomarker for monitoring treatment response in PAH.

Do arginine metabolites have a role in periodontitis due to smoking? A new perspective

OBJECTIVES

Cigarette consumption is common around the world and besides its negative effects on health, and its effects on periodontitis draw attention. Arginine metabolites are involved in the pathogenesis of several systemic inflammatory diseases' including cardiovascular diseases. Our aim was to determine periodontitis and healthy individuals' arginine metabolites and IL-6 levels in saliva and serum and to evaluate those according to smoking status.

MATERIALS AND METHODS

The study consisted of four groups: healthy individuals (control [C]; n = 20), smokers with healthy periodontium (S-C; n = 20), nonsmokers with Stage-III Grade-B generalized periodontitis (P; n = 20) and smokers with Stage-III Grade-C generalized periodontitis (S-P; n = 18). Periodontal parameters were measured. Analysis of methylated arginine metabolites was performed by LC-MS/MS, and IL-6 levels were determined by ELISA kits.

RESULTS

In nonsmokers, salivary concentrations of asymmetric dimethylarginine (ADMA) and symmetrical dimethylarginine (SDMA) were higher in the periodontitis than control (p < 0.001, p = 0.010). Smokers with periodontitis exhibited higher ADMA (p = 0.033, p < 0.001) and arginine (p = 0.030, p = 0.001) saliva concentrations than smoking and nonsmoking controls.

CONCLUSIONS

Our results demonstrated that salivary concentrations of ADMA and SDMA were associated with periodontitis. Smoking increased ADMA, SDMA and NG -monomethyl L-arginine (L-NMMA) levels in serum only in periodontitis patients.

Strong Association of Metabolic Parameters with ADMA and VCAM-1 in Normo-Weight Subjects with Metabolic Syndrome

Background

Metabolic syndrome (MetS) is a risk factor for cardiovascular disease and is linked to obesity. Subjects with MetS who have normo-weight potentially show higher mortality and morbidity.

Purpose

This study aims to reveal the critical essential metabolic parameters associated with endothelial dysfunction in MetS subjects with normo-weight compared to obese.

Patients and Methods

The study was designed using a case-control approach. Ninety-nine MetS subjects (34 Normo-weight and 65 obese) from the urban population were enrolled in this study. The components of MetS are based on NCEP/ATP III criteria. Asymmetric dimethylarginine (ADMA) and vascular cell adhesion molecule 1 (VCAM-1) as markers for endothelial dysfunction were measured in both groups.

Results

Fasting blood glucose (FBG) levels were higher in the normo-weight group (143.38 ± 79.8 mg/dL) compared to the obese group (120.89 ± 46.5 mg/dL). High-density lipoprotein cholesterol (HDL-c) levels in the normo-weight group were lower (42.82 ± 10.1 mg/dL) compared to obesity (45.74 ± 9.3 mg/dL), while triacylglycerol (TAG) levels were higher in the obese (197.25 ± 110.5 mg/dL) compared to the normo-weight group (167.03 ± 98.4 mg/dL), although the differences were statistically not significant (all p > 0.05). The difference between ADMA and VCAM-1 levels was statistically not significant in both groups. Correlation between MetS components with endothelial dysfunction parameters shows that metabolic parameters correlate strongly. Interestingly, a stronger correlation between FBG and ADMA was observed in normo-weight (r = 0.519) compared to obese groups (r = 0.445). In addition, TAG consistently shows a significant correlation with ADMA and VCAM-1 in normo-weight groups.

Conclusion

Metabolic parameters, especially FBG and TAG, correlate strongly with endothelial dysfunction parameters in normo-weight subjects with metabolic syndrome.

All That Glitters Is Not Gold: Assessment of Bee Pollen Supplementation Effects on Gastric Mucosa

The aim of this study was to assess the influence of bee pollen supplementation on the levels of enzymes important for gastric mucosal homeostasis, namely cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and a biomarker-asymmetric dimethylarginine (ADMA)-in the gastric mucosa of Wistar rats. The experimental phase divided the rats into four groups: two control groups, sedentary and active, both not supplemented, and two experimental groups, sedentary and active, supplemented with bee pollen. The results indicated that bee pollen supplementation reduced the levels of COX-1 and elevated iNOS levels, while showing no significant impact on COX-2 levels. These findings do not conclusively support the gastroprotective and anti-inflammatory effects of bee pollen on gastric mucosa. However, the supplementation could have resulted in reduced ADMA levels in the physically active supplemented group. Our study does not unequivocally demonstrate the positive effects of bee pollen supplementation on the gastric mucosa, which may be attributed to the specific metabolism and bioavailability of substances within unprocessed, dried bee pollen. Further research should explore the topic of potential therapeutic applications of bee pollen in gastrointestinal health and its interactions with ADMA signaling pathways.

Circulating arginine metabolites in Alzheimer's disease and vascular dementia: A systematic review and meta-analysis

BACKGROUND

Alterations in nitric oxide (NO) synthesis have been reported in Alzheimer's disease and vascular dementia. However, as the measurement of NO in biological samples is analytically challenging, alternative, stable circulatory biomarkers of NO synthesis may be useful to unravel new pathophysiological mechanisms and treatment targets in dementia.

METHODS

We conducted a systematic review and meta-analysis of the circulating concentrations of arginine metabolites linked to NO synthesis, arginine, citrulline, asymmetric (ADMA) and symmetric (SDMA) dimethylarginine, and ornithine, in Alzheimer's disease and vascular dementia. We searched for relevant studies in PubMed, Scopus, and Web of Science from inception to the 31st of May 2023. The JBI checklist and GRADE were used to assess the risk of bias and the certainty of evidence, respectively.

RESULTS

In 14 selected studies, there were no significant between-group differences in arginine and ornithine concentrations. By contrast, compared to controls, patients with dementia had significantly higher ADMA (standard mean difference, SMD=0.62, 95% CI 0.06-1.19, p = 0.029), SDMA (SMD=0.70, 95% CI 0.34-1.35, p<0.001), and citrulline concentrations (SMD=0.50, 95% CI 0.08-0.91, p = 0.018). In subgroup analysis, the effect size was significantly associated with treatment with cholinesterase inhibitors and/or antipsychotics for ADMA, and underlying disorder (Alzheimer's disease), study continent, and analytical method for citrulline.

CONCLUSION

Alterations in ADMA, SDMA, and citrulline, biomarkers of NO synthesis, may be useful to investigate the pathophysiology of different forms of dementia and identify novel therapeutic strategies. (PROSPERO registration number: CRD42023439528).

Klotho and lean mass as novel cardiovascular risk factors in hemodialysis patients

Background

Patients with chronic kidney disease (CKD) present a higher risk of cardiovascular (CV) morbidity and mortality compared with the general population. While there are several well-established traditional CV risk factors, few studies have addressed novel potential risk factors such as α-Klotho, asymmetric dimethylarginine (ADMA) and lean mass.

Methods

This was an observational, prospective, single-center, cohort study that included prevalent hemodialysis (online hemodiafiltration) adult patients. By univariate logistic regression models, univariate and multivariate Cox proportional hazards models, and Kaplan-Meier analysis, we evaluated the association between the levels of α-Klotho, ADMA and lean mass, with the risk of peripheral vascular disease (PVD), CV events and all-cause mortality in these patients.

Results

A total of 200 HD patients was included. We found that increased levels of log-α-Klotho were significantly associated with decreased odds of both PVD [odds ratio (OR) 0.521, 95% confidence interval (CI) 0.270-0.954, P = .034] and CV events (OR 0.415, 95% CI 0.203-0.790, P = .01), whereas increased levels of log-ADMA were only significantly associated with increased odds of PVD (OR 13.482, 95% CI 5.055-41.606, P < .001). We also found that the levels of log-α-Klotho (HR 0.357, 95% CI 0.140-0.906, P < .05) and lean mass (HR 0.187, 95% CI 0.042-0.829, P < .05), but not log-ADMA, were significantly associated with the risk of all-cause mortality, even after adjusting for possible confounding variables.

Conclusions

Novel long-term clinical associations were generated that support α-Klotho and lean mass as novel CV risk factors in hemodialysis patients.

Plasma arginine metabolites in health and chronic kidney disease

BACKGROUND

Elevated plasma asymmetric and symmetric dimethylarginine (ADMA and SDMA) are risk factors for chronic kidney disease (CKD) and cardiovascular disease. Using plasma cystatin C (pCYSC)-based estimated glomerular filtration rate (eGFR) trajectories, we identified a cohort at high risk of poor kidney-related health outcomes amongst members of the Dunedin Multidisciplinary Health and Development Study (DMHDS). We therefore examined associations between methylarginine metabolites and kidney function in this cohort.

METHODS

ADMA, SDMA, L-arginine and L-citrulline were measured in plasma samples from 45-year-olds in the DMHDS cohort by liquid chromatography-tandem mass spectrometry.

RESULTS

In a healthy DMHDS subset (n = 376), mean concentrations were: ADMA (0.40 ± 0.06 µmol/L), SDMA (0.42 ± 0.06 µmol/L), L-arginine (93.5 ± 23.1 µmol/L) and L-citrulline (24.0 ± 5.4 µmol/L). In the total cohort (n = 857), SDMA correlated positively with serum creatinine (Pearson's r = 0.55) and pCYSC (r = 0.55), and negatively with eGFR (r = 0.52). A separate cohort of 38 patients with stage 3-4 CKD (eGFR 15-60 mL/min/1.73 m2) confirmed significantly higher mean ADMA (0.61 ± 0.11 µmol/L), SDMA (0.65 ± 0.25 µmol/L) and L-citrulline (42.7 ± 11.8 µmol/L) concentrations. DMHDS members classified as high-risk of poor kidney health outcomes had significantly higher mean concentrations of all four metabolites compared with individuals not at risk. ADMA and SDMA individually predicted high-risk of poor kidney health outcomes with areas under the ROC curves (AUCs) of 0.83 and 0.84, and together with an AUC of 0.90.

CONCLUSIONS

Plasma methylarginine concentrations facilitate stratification for risk of CKD progression.

Human pulmonary microvascular endothelial cell DDAH1-mediated nitric oxide production promotes pulmonary smooth muscle cell apoptosis in co-culture

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in preterm infants, and pulmonary hypertension (PH) develops in 25%-40% of patients with BPD, increasing morbidity and mortality. BPD-PH is characterized by vasoconstriction and vascular remodeling. Nitric oxide (NO) is a pulmonary vasodilator and apoptotic mediator made in the pulmonary endothelium by NO synthase (eNOS). Asymmetric dimethylarginine (ADMA) is an endogenous eNOS inhibitor, primarily metabolized by dimethylarginine dimethylaminohydrolase-1 (DDAH1). Our hypothesis is that DDAH1 knockdown in human pulmonary microvascular endothelial cells (hPMVEC) will result in lower NO production, decreased apoptosis, and greater proliferation of human pulmonary arterial smooth muscle cells (hPASMC), whereas DDAH1 overexpression will have the opposite effect. hPMVECs were transfected with small interfering RNA targeting DDAH1 (siDDAH1)/scramble or adenoviral vector containing DDAH1 (AdDDAH1)/AdGFP for 24 h and co-cultured for 24 h with hPASMC. Analyses included Western blot for cleaved and total caspase-3, caspase-8, caspase-9, β-actin; trypan blue exclusion for viable cell numbers; terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL); and BrdU incorporation. Small interfering RNA targeting DDAH1 (siDDAH1) transfected into hPMVEC resulted in lower media nitrites, cleaved caspase-3 and caspase-8 protein expression, and TUNEL staining; and greater viable cell numbers and BrdU incorporation in co-cultured hPASMC. Adenoviral-mediated transfection of the DDAH1 gene (AdDDAH1) into hPMVEC resulted in greater cleaved caspase-3 and caspase-8 protein expression and lower viable cell numbers in co-cultured hPASMC. Partial recovery of hPASMC viable cell numbers after AdDDAH1-hPMVEC transfection was observed when media were treated with hemoglobin to sequester NO. In conclusion, hPMVEC-DDAH1-mediated NO production positively regulates hPASMC apoptosis, which may prevent/attenuate aberrant pulmonary vascular proliferation/remodeling in BPD-PH.NEW & NOTEWORTHY BPD-PH is characterized by vascular remodeling. NO is an apoptotic mediator made in the pulmonary endothelium by eNOS. ADMA is an endogenous eNOS inhibitor metabolized by DDAH1. EC-DDAH1 overexpression resulted in greater cleaved caspase-3 and caspase-8 protein expression and lower viable cell numbers in co-cultured SMC. After NO sequestration, SMC viable cell numbers partially recovered despite EC-DDAH1 overexpression. EC-DDAH1-mediated NO production positively regulates SMC apoptosis, which may prevent/attenuate aberrant pulmonary vascular proliferation/remodeling in BPD-PH.

Blood pressure response to exercise in unaffected relatives of autosomal dominant polycystic kidney disease patients: an observational study

INTRODUCTION

Hypertension is an early finding of autosomal dominant polycystic kidney disease (ADPKD) and is related to different mechanisms. Cyst expansion-related renin secretion or early endothelial dysfunctions are some of these hypotheses. In addition, the underlying genetic factor is thought to play a role in the inheritance of hypertension. The differential course of hypertension in ADPKD preoccupies that relatives of ADPKD patients may also be at risk for this underlying mechanisms with a genetically determined abnormal endothelial-vascular state. In this study, we aimed to evaluate blood pressure response to exercise as an initial vascular problem in unaffected and normotensive relatives of hypertensive ADPKD patients.

METHODS

This is an observational study including unaffected and normotensive relatives (siblings and children) of ADPKD patients (relative group) and healthy controls (control group) who performed an exercise stress test. A 6-lead electrocardiogram was recorded and blood pressure was measured automatically with a cuff worn on the right arm, immediately before the test and every 3 min during the exercise and the recovery phase. Participants continued the test until their age-specific target heart rate was reached or symptoms occurred that required discontinuation of the test. The highest blood pressure and pulse values during exercise were noted. In addition, as a marker for endothelial function, nitric oxide (NO) and asymmetric dimethylarginine (ADMA) levels were measured at baseline and post-exercise.

RESULTS

There were 24 participants in the relative group (16 female, mean age 38.45 years) and 30 participants in the control group (15 female, mean age 37.96 years). Two groups were similar in terms of age, gender, body mass index (BMI), smoking status, resting systolic blood pressure (SBP)/diastolic blood pressure (DBP) and biochemical parameters. Mean SBP and DBP were similar in both groups during 1st, 3rd and 9th minutes of exercise (1st minute: 136.25 ± 19.71 mmHg vs 140.36 ± 30.79 mmHg for SBP, p = 0.607, 84.05 ± 14.75 mmHg vs 82.60 ± 21.60 mmHg for DBP, p = 0.799; 3rd minute: 150.75 ± 30.39 mmHg vs 148.54 ± 27.30 mmHg for SBP, p = 0.801, 98.95 ± 26.92 mmHg vs 85.92 ± 17.93 mmHg for DBP, p = 0.062; 9th minute: 156.35 ± 30.84 mmHg vs 166.43 ± 31.90 mmHg for SBP, p = 0.300, 96.25 ± 21.99 mmHg vs 101.78 ± 33.11 mmHg for DBP, p = 0.529 for control and relatives, respectively). During the recovery phase, SBP decreased in both groups in 6th minute (119.85 ± 14.06 mmHg vs 122.86 ± 16.76 mmHg, p = 0.538 for control and relatives respectively); however, in the relatives of ADPKD patients DBP remained high at the end of the 6th minute (78.95 ± 11.29 mmHg vs 86.67 ± 9.81 mmHg p = 0.025 for control and relatives, respectively). Baseline and post-exercise NO and ADMA levels were similar in both groups (Baseline p = 0.214 and p = 0.818, post-exercise p = 0.652 and p = 0.918 for NO and ADMA, respectively).

CONCLUSION

Abnormal blood pressure response to exercise was observed in unaffected normotensive relatives of ADPKD. Although its clinical significance needs to be demonstrated by additional research, it is an important finding that unaffected relatives of ADPKD may be at risk for an altered arterial vascular network. Furthermore, these data are the first to demonstrate that relatives of ADPKD patients may also be under risk with a genetically determined abnormal vascular state.

Vitamin D Supplementation Influences Ultramarathon-Induced Changes in Serum Amino Acid Levels, Tryptophan/Branched-Chain Amino Acid Ratio, and Arginine/Asymmetric Dimethylarginine Ratio

Exercise affects serum levels of amino acids and their metabolites, with important metabolic consequences. Since vitamin D impacts skeletal muscle protein degradation, we hypothesised that it would also impact exercise-induced changes in serum amino acid levels and the serum levels of arginine metabolites, influencing the body's ability to synthesise NO. Accordingly, we analysed the effect of a single high-dose vitamin D supplementation on the serum levels of various amino acids in ultramarathon runners. Thirty-five male amateur runners were assigned to the supplemented group, administered 150,000 IU vitamin D in vegetable oil 24 h before the run (n = 16), or the control (placebo) group (n = 19). Blood was sampled 24 h before, immediately after, and 24 h after the run. Changes in the serum levels of some amino acids were distinct in the two groups. The asymmetric dimethyl arginine levels were significantly decreased immediately after the run and increased 24 h later and were not affected by the supplementation. The symmetric dimethyl arginine levels were increased after the run in both groups but were lower in the supplemented group than in the placebo group 24 h after the run. The dimethylamine levels increased significantly in the supplemented group as compared to the placebo group. In conclusion, vitamin D impacts exercise-induced changes in serum amino acids and methylated arginine metabolites.

Biomarkers of the L-Arginine/Dimethylarginine/Nitric Oxide Pathway in People with Chronic Airflow Obstruction and Obstructive Sleep Apnoea

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea (OSA) are common chronic diseases that are associated with chronic and intermittent hypoxemia, respectively. Patients affected by the overlap of COPD and OSA have a particularly unfavourable prognosis. The L-arginine/nitric oxide (NO) pathway plays an important role in regulating pulmonary vascular function. Asymmetric (ADMA) and symmetric dimethylarginine (SDMA) interfere with NO production.

METHODS

We analysed the serum concentrations of ADMA, SDMA, L-arginine, L-citrulline, and L-ornithine in a large sample of the Icelandic general population together with chronic airflow obstruction (CAO), a key physiological marker of COPD that was assessed by post-bronchodilator spirometry (FEV1/FVC < LLN). OSA risk was determined by the multivariable apnoea prediction (MAP) index.

RESULTS

713 individuals were analysed, of whom 78 (10.9%) showed CAO and 215 (30%) had MAP > 0.5. SDMA was significantly higher in individuals with CAO (0.518 [0.461-0.616] vs. 0.494 [0.441-0.565] µmol/L; p = 0.005), but ADMA was not. However, ADMA was significantly associated with decreasing FEV1 percent predicted among those with CAO (p = 0.002). ADMA was 0.50 (0.44-0.56) µmol/L in MAP ≤ 0.5 versus 0.52 (0.46-0.58) µmol/L in MAP > 0.5 (p = 0.008). SDMA was 0.49 (0.44-0.56) µmol/L versus 0.51 (0.46-0.60) µmol/L, respectively (p = 0.004). The highest values for ADMA and SDMA were observed in individuals with overlap of CAO and MAP > 0.5, which was accompanied by lower L-citrulline levels.

CONCLUSIONS

The plasma concentrations of ADMA and SDMA are elevated in COPD patients with concomitant intermittent hypoxaemia. This may account for impaired pulmonary NO production, enhanced pulmonary vasoconstriction, and disease progression.

Vascular nitrosative stress in hypertension induced by fetal undernutrition in rats

Fetal undernutrition predisposes to hypertension development. Since nitric oxide (NO) is a key factor in blood pressure control, we aimed to investigate the role of NO alterations in hypertension induced by fetal undernutrition in rats. Male and female offspring from dams exposed to undernutrition during the second half of gestation (MUN) were studied at 21 days (normotensive) and 6 months of age (hypertension developed only in males). In aorta, we analyzed total and phosphorylated endothelial NO synthase (eNOS, p-eNOS), 3-nitrotyrosine (3-NT), and Nrf2 (Western blot). In plasma we assessed L-arginine, asymmetric and symmetric dimethylarginine (ADMA, SDMA; LC-MS/MS), nitrates (NOx, Griess reaction), carbonyl groups, and lipid peroxidation (spectrophotometry). In iliac arteries, we studied superoxide anion production (DHE staining, confocal microscopy) and vasodilatation to acetylcholine (isometric tension). Twenty-one-day-old MUN offspring did not show alterations in vascular e-NOS or 3NT expression, plasma L-Arg/ADMA ratio, or NOx. Compared to control group, 6-month-old MUN rats showed increased aortic expression of p-eNOS/eNOS and 3-NT, being Nrf2 expression lower, elevated plasma L-arginine/ADMA, NOx and carbonyl levels, increased iliac artery DHE staining and reduced acetylcholine-mediated relaxations. These alterations in MUN rats were sex-dependent, affecting males. However, females showed some signs of endothelial dysfunction. We conclude that increased NO production in the context of a pro-oxidative environment, leads to vascular nitrosative damage and dysfunction, which can participate in hypertension development in MUN males. Females show a better adaptation, but signs of endothelial dysfunction, which can explain hypertension in ageing.

Hepatic DDAH1 mitigates hepatic steatosis and insulin resistance in obese mice: Involvement of reduced S100A11 expression

Dimethylarginine dimethylaminohydrolase 1 (DDAH1) is an important regulator of plasma asymmetric dimethylarginine (ADMA) levels, which are associated with insulin resistance in patients with nonalcoholic fatty liver disease (NAFLD). To elucidate the role of hepatic DDAH1 in the pathogenesis of NAFLD, we used hepatocyte-specific Ddah1-knockout mice (Ddah1HKO) to examine the progress of high-fat diet (HFD)-induced NAFLD. Compared to diet-matched flox/flox littermates (Ddah1f/f), Ddah1HKO mice exhibited higher serum ADMA levels. After HFD feeding for 16 weeks, Ddah1HKO mice developed more severe liver steatosis and worse insulin resistance than Ddah1f/f mice. On the contrary, overexpression of DDAH1 attenuated the NAFLD-like phenotype in HFD-fed mice and ob/ob mice. RNA-seq analysis showed that DDAH1 affects NF-κB signaling, lipid metabolic processes, and immune system processes in fatty livers. Furthermore, DDAH1 reduces S100 calcium-binding protein A11 (S100A11) possibly via NF-κB, JNK and oxidative stress-dependent manner in fatty livers. Knockdown of hepatic S100a11 by an AAV8-shS100a11 vector alleviated hepatic steatosis and insulin resistance in HFD-fed Ddah1HKO mice. In summary, our results suggested that the liver DDAH1/S100A11 axis has a marked effect on liver lipid metabolism in obese mice. Strategies to increase liver DDAH1 activity or decrease S100A11 expression could be a valuable approach for NAFLD therapy.

Comparison of BTP, NGAL, KIM-1, & ADMA biomarkers in CKD and non-CKD subjects

INTRODUCTION

New biomarkers, such as neutrophil gelatinase-associated lipocalin (NGAL), a member of the lipocalin family, and kidney injury molecule-1 (KIM-1) have been utilised in recent years to identify the development of chronic kidney disease (CKD). However, attempts to use them as broad markers to check for renal injury in patients and to pinpoint the kidney injury site have been unsuccessful. Therefore the search for an ideal panel of biomarkers predicting progression of CKD is still ongoing. The present study is designed to evaluate the biomarkers for CKD from NGAL, KIM-1, Beta trace protein (BTP) and Asymmetric dimethylarginine (ADMA).

MATERIALS AND METHODS

For this case-control study, 100 participants were selected on the basis of inclusion and exclusion criteria at the Index Medical College Hospital and Research Centre, Madhya Pradesh, there were 67 male subjects and 33 female CKD subjects and 100 non-CKD subjects (60 male and 40 female) matched for age and sex were taken from the hospital.

RESULTS

Between the CKD and non-CKD participants, the levels of BTP, plasma NGAL, KIM-1, and ADMA were compared and found to be substantially higher than those in the controls.

CONCLUSION

Abnormal renal function is linked to disturbed blood levels of BTP, NGAL, KIM-1, and ADMA. Strong correlations exist between increased blood levels of BTP, NGAL, KIM-1, and ADMA and reduced kidney function. They might thus be used to estimate the decline of renal function and the progression of CKD.

The effect of exenatide (a GLP-1 analogue) and sitagliptin (a DPP-4 inhibitor) on asymmetric dimethylarginine (ADMA) metabolism and selected biomarkers of cardiac fibrosis in rats with fructose-induced metabolic syndrome

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis, is a risk factor for endothelial dysfunction, a common pathophysiological denominator for both atherogenesis and cardiac fibrosis. We aimed to investigate whether the cardioprotective and antifibrotic effects of incretin drugs, exenatide and sitagliptin, may be associated with their ability to affect circulating and cardiac ADMA metabolism. Normal and fructose-fed rats were treated with sitagliptin (5.0/10 mg/kg) or exenatide (5/10 µg/kg) for 4 weeks. The following methods were used: LC-MS/MS, ELISA, Real-Time-PCR, colorimetry, IHC and H&E staining, PCA and OPLS-DA projections. Eight-week fructose feeding resulted in an increase in plasma ADMA and a decrease in NO concentration. Exenatide administration into fructose-fed rats reduced the plasma ADMA level and increased NO level. In the heart of these animals exenatide administration increased NO and PRMT1 level, reduced TGF-ß1, α-SMA levels and COL1A1 expression. In the exenatide treated rats renal DDAH activity positively correlated with plasma NO level and negatively with plasma ADMA level and cardiac α-SMA concentration. Sitagliptin treatment of fructose-fed rats increased plasma NO concentration, reduced circulating SDMA level, increased renal DDAH activity and reduced myocardial DDAH activity. Both drugs attenuated the myocardial immunoexpression of Smad2/3/P and perivascular fibrosis. In the metabolic syndrome condition both sitagliptin and exenatide positively modulated cardiac fibrotic remodeling and circulating level of endogenous NOS inhibitors but had no effects on ADMA levels in the myocardium.

Renal Function Underpins the Cyclooxygenase-2: Asymmetric Dimethylarginine Axis in Mouse and Man

Introduction

Through the production of prostacyclin, cyclooxygenase (COX)-2 protects the cardiorenal system. Asymmetric dimethylarginine (ADMA), is a biomarker of cardiovascular and renal disease. Here we determined the relationship between COX-2/prostacyclin, ADMA, and renal function in mouse and human models.

Methods

We used plasma from COX-2 or prostacyclin synthase knockout mice and from a unique individual lacking COX-derived prostaglandins (PGs) because of a loss of function mutation in cytosolic phospholipase A2 (cPLA2), before and after receiving a cPLA2-replete transplanted donor kidney. ADMA, arginine, and citrulline were measured using ultra-high performance liquid-chromatography tandem mass spectrometry. ADMA and arginine were also measured by enzyme-linked immunosorbent assay (ELISA). Renal function was assessed by measuring cystatin C by ELISA. ADMA and prostacyclin release from organotypic kidney slices were also measured by ELISA.

Results

Loss of COX-2 or prostacyclin synthase in mice increased plasma levels of ADMA, citrulline, arginine, and cystatin C. ADMA, citrulline, and arginine positively correlated with cystatin C. Plasma ADMA, citrulline, and cystatin C, but not arginine, were elevated in samples from the patient lacking COX/prostacyclin capacity compared to levels in healthy volunteers. Renal function, ADMA, and citrulline were returned toward normal range when the patient received a genetically normal kidney, capable of COX/prostacyclin activity; and cystatin C positively correlated with ADMA and citrulline. Levels of ADMA and prostacyclin in conditioned media of kidney slices were not altered in tissue from COX-2 knockout mice compared to wildtype controls.

Conclusion

In human and mouse models, where renal function is compromised because of loss of COX-2/PGI2 signaling, ADMA levels are increased.

The effects of melatonin against atherosclerosis-induced endothelial dysfunction and inflammation in hypercholesterolemic rats

The aim of this study was to investigate the effects of melatonin on the serum asymmetric dimethylarginine (ADMA) levels and the expressions of vaspin, visfatin, dimethylarginine dimethylaminohydrolase (DDAH), and signal transducer and activator of transcription-3 (STAT-3) for evaluation of endothelial function and inflammation in the hypercholesterolemic rats. Rats were divided into 5 groups: (1) control, (2) hypercholesterolaemia, (3) melatonin administrated concurrently with cholesterol diet, (4) melatonin administrated only last 2 weeks and fed with cholesterol diet, (5) atorvastatin administered only last 2 weeks fed with cholesterol diet. Although an increase was observed in the expressions of visfatin and STAT-3 and the serum ADMA levels, the vaspin and DDAH protein expressions were found to decrease with hypercholesterolemic diets. Melatonin was determined to restore all the parameters to the normal levels. In conclusion, melatonin may have protective and therapeutic effects on hypercholesterolaemia by regulating vaspin, STAT-3, DDAH, and ADMA signalling pathways and create similar effects with atorvastatin.

The role of asymmetric dimethylarginine in endothelial dysfunction and abnormal nitric oxide metabolism in systemic sclerosis: results from a pilot study

INTRODUCTION/OBJECTIVES

Systemic sclerosis (SSc) is characterized by generalized vasculopathy affecting mainly small vessels while macrovascular involvement is less investigated. The aim of this study was to examine associations between asymmetric dimethylarginine (ADMA) - a biomarker of atherosclerosis - and assessments of macrovascular endothelial function in patients with SSc.

METHODS

This was a cross-sectional study including consecutive SSc patients attending the Scleroderma Outpatient Clinic. ADMA measurement in serum samples was based on an enzyme immunoassay technique. Participants underwent blood pressure measurement according to 2018 ESC/ESH Guidelines, applanation tonometry for the evaluation of arterial stiffness, and carotid ultrasound for the measurement of the intima-media thickness (cIMT).

RESULTS

Eighty-one Caucasians (82.3% female) SSc individuals with mean age 55.44 ± 13.4 years were included in this analysis. The correlation analysis of ADMA levels (unadjusted and adjusted values) with functional and morphological parameters of atherosclerosis revealed no statistically significant associations. Subgroup analysis based on disease duration (≤ 4 years), immunologic profile (SCL-70 and ACA antibodies), disease type (limited, diffuse), and inflammatory status (erythrocyte sedimentation rate [ESR] > 25 mm/h and C-reactive protein [CRP] > 5 mg/L) showed no associations, except from a significant positive correlation between ADMA levels and cΙΜΤ_mean (r = 0.370, p = 0.044) in individuals with early SSc.

CONCLUSIONS

The results of the study suggest that ADMA may be related with accelerated atherosclerosis in early stages of the disease. However, the lack of association between other morphological and functional parameters of endothelial dysfunction may suggest that other regulators of nitric oxide metabolism may contribute to macrovascular injury in SSc in various phases of the disease. Key Points • ADMA is a biomarker of atherosclerosis and has been linked with microvascular complications of SSc. •ADMA was not correlated with morphological and functional parameters of atherosclerosis in the population of the study. •The demonstrated association between ADMA and cIMT in patients with early SSc may suggest a role of NO/ADMA pathway in the initiation of macrovascular injury in SSc.

High-throughput quantitation of serological dimethylarginines by LC/MS/MS: Potential cardiovascular biomarkers for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by systemic inflammation of the joints and extra-articular tissues. The incidence of cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with RA. Despite the development of new therapeutics targeting the articular manifestations, the relief of the cardiovascular burden is still an unmet medical need during the management of RA. So, the early prognosis of RA-associated CVD plays a crucial role in improving the clinical outcomes of RA patients. Recently, circulating dimethylarginines have gained attention as potential biomarkers for CVDs. Here, we present the development and validation of a high-throughput liquid chromatography-tandem mass spectrometric (LC/MS/MS) method for simultaneous quantification of creatinine, arginine, and dimethylarginines in human serum within 2 mins by isotope dilution mass spectrometry. This method employed a protein precipitation method for rapid sample preparation, trichloroacetic acid (TCA)-based ion pairing chromatography for fast analyte separation, and multiple reaction monitoring (MRM) with stable isotope-labeled internal standards (ISs) for simultaneous quantitation. To assure the quality, our method was validated against the FDA guidelines for lower limit of quantitation (0.2 µM), linearity (square of coefficient correlation>0.99), precision (intra-&inter-assay imprecision < 10 %), accuracy (intra-&inter-assay inaccuracy < 10 %), sample preparation recovery (recovery ≥ 90 %), stability (instability < 10 %), matrix effect (signal suppression < 55 %), and carryover ( < 0.01 %). Afterward, we applied the validated method to a retrospective cross-sectional study. We aimed to evaluate the utility of serological dimethylarginines as potential cardiovascular biomarkers in the development of RA-associated CVD. Our results revealed that the serological ratio of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA), an indicator of physiological arginine methylation status, was significantly elevated in patients with RA. This finding might provide value in detecting CVD to improve clinical outcomes in RA management.

Endothelial dysfunction due to eNOS uncoupling: molecular mechanisms as potential therapeutic targets

Nitric oxide (NO) is one of the most important molecules released by endothelial cells, and its antiatherogenic properties support cardiovascular homeostasis. Diminished NO bioavailability is a common hallmark of endothelial dysfunction underlying the pathogenesis of the cardiovascular disease. Vascular NO is synthesized by endothelial nitric oxide synthase (eNOS) from the substrate L-arginine (L-Arg), with tetrahydrobiopterin (BH₄) as an essential cofactor. Cardiovascular risk factors such as diabetes, dyslipidemia, hypertension, aging, or smoking increase vascular oxidative stress that strongly affects eNOS activity and leads to eNOS uncoupling. Uncoupled eNOS produces superoxide anion (O₂^-) instead of NO, thus becoming a source of harmful free radicals exacerbating the oxidative stress further. eNOS uncoupling is thought to be one of the major underlying causes of endothelial dysfunction observed in the pathogenesis of vascular diseases. Here, we discuss the main mechanisms of eNOS uncoupling, including oxidative depletion of the critical eNOS cofactor BH₄, deficiency of eNOS substrate L-Arg, or accumulation of its analog asymmetrical dimethylarginine (ADMA), and eNOS S-glutathionylation. Moreover, potential therapeutic approaches that prevent eNOS uncoupling by improving cofactor availability, restoration of L-Arg/ADMA ratio, or modulation of eNOS S-glutathionylation are briefly outlined.

Effect of cigarette smoking on serum methylarginine and α-klotho levels

BACKGROUND AND AIMS

Smoking causes many diseases such as cardiovascular, lung diseases, stroke and premature aging. However, the role of smoking in the pathogenesis of these diseases is unclear. Increasing evidence suggests that methylarginine pathway metabolites and α-klotho may be strong markers for pathologies such as premature aging, endothelial dysfunction, and oxidant damage. Therefore, the study aimed to measure the serum levels of arginine, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), N-monomethyl-l-arginine (L-NMMA), and α-klotho levels in smokers.

METHODS AND RESULTS

This case-control analytical study included 65 smokers and 71 non-smokers. Sociodemographic characteristics, routine biochemistry parameters, Framingham risk scores and Fagerström Nicotine Dependence Test (FTND) were recorded. Serum methylarginine and α-klotho levels were analyzed by tandem mass spectrometry and enzyme-linked immunosorbent assay (ELISA), respectively. Serum ADMA (p < 0.001), L-NMMA (p = 0.024), SDMA (p < 0.001) levels of smokers were higher than non-smokers, and serum α-klotho (p < 0.001) and arginine levels (p < 0.001) were lower. There was a positive correlation between serum ADMA levels with FNDT, age and pack/year in smokers, while there was a negative correlation between klotho levels and age. A positive correlation was found between serum ADMA levels, Framingham risk score and age in non-smokers.

CONCLUSION

Smoking is related to premature aging and is a strong risk factor for various diseases such as cardiovascular, inflammatory, and renal diseases. Elevated serum methylarginine and decreased serum klotho levels were found in smokers. Therefore, our findings suggest that smoking may be involved in the pathogenesis of these diseases by affecting α-klotho and methylarginine-related pathways.

Metabolomic markers mediate erythrocyte anisocytosis in older adults: Results from three independent aging cohorts

BACKGROUND

Anisocytosis reflects unequal-sized red blood cells and is quantified using red blood cell distribution width (RDW). RDW increases with age and has been consistently associated with adverse health outcomes, such as cardiovascular disease and mortality. Why RDW increases with age is not understood. We aimed to identify plasma metabolomic markers mediating anisocytosis with aging.

METHODS

We performed mediation analyses of plasma metabolomics on the association between age and RDW using resampling techniques after covariate adjustment. We analyzed data from adults aged 70 or older from the main discovery cohort of the Baltimore Longitudinal Study of Aging (BLSA, n = 477, 46% women) and validation cohorts of the Health, Aging and Body Composition Study (Health ABC, n = 620, 52% women) and Invecchiare in Chianti, Aging in the Chianti Area (InCHIANTI) study (n = 735, 57% women). Plasma metabolomics was assayed using the Biocrates MxP Quant 500 kit in BLSA and Health ABC and liquid chromatography with tandem mass spectrometry in InCHIANTI.

RESULTS

In all three cohorts, symmetric dimethylarginine (SDMA) significantly mediated the association between age and RDW. Asymmetric dimethylarginine (ADMA) and 1-methylhistidine were also significant mediators in the discovery cohort and one validation cohort. In the discovery cohort, we also found choline, homoarginine, and several long-chain triglycerides significantly mediated the association between age and RDW.

CONCLUSIONS AND RELEVANCE

This metabolomics study of three independent aging cohorts identified a specific set of metabolites mediating anisocytosis with aging. Whether SDMA, ADMA, and 1-methylhistidine are released by the damaged erythrocytes with high RDW or they affect the physiology of erythrocytes causing high RDW should be further investigated.

Asymmetric dimethylarginine correlates with worsening peripheral microangiopathy in systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a connective tissue disease characterized primarily by micro-angiopathy and endothelial dysfunction which stimulate a fibrotic process. Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide (NO) inhibitor and represents a novel biomarker for vascular dysfunction. Nailfold video capillaroscopy (NVC) represents a non-invasive and reliable technique for the evaluation of microvasculopathy in SSc.

OBJECTIVES

The aim of this study was to examine the possible association between ADMA and microvascular involvement in patients with SSc.

METHODS

This was a cross-sectional study including consecutive SSc patients attending the Scleroderma Outpatient Clinic. ADMA was measured in serum samples using a commercial enzyme immunoassay. Participants underwent NVC with qualitative and semi-quantitative assessment and all NVC parameters were measured in the distal row of each finger. The findings were classified in one of the three qualitative NVC patterns: early, active, and late.

RESULTS

Eighty-one (92,6 % women) SSc individuals with mean age 55.44 ± 13.4 years were included in this analysis. Within-groups comparisons revealed a trend between higher ADMA levels and progressive micro-vasculopathy (1,29 [2,1] vs 1,57 [1,95] vs 2,41 [3,87]; for early, active and late patterns respectively, p = 0.039). Furthermore, ADMA concentration was significantly associated with the number of capillaries/mm (r = -0.235; p = 0.035).

CONCLUSIONS

Serum ADMA levels were significantly associated with advancing stages of microcirculatory abnormalities suggesting that ADMA may have a role in promoting microvascular endothelial dysfunction in SSc individuals.

The ADMA-DDAH1 axis in ovarian apoptosis of polycystic ovary syndrome

Dimethylarginine dimethylaminohydrolase 1 (DDAH1) mainly degrades asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor. Emerging evidence suggested that plasma ADMA is accumulated in patients with polycystic ovary syndrome (PCOS). However, ADMA-DDAH1 involvement in PCOS pathogenesis is unclear. Here, we used dehydroepiandrosterone (DHEA)-induced PCOS rats and the ovarian granulosa cell line KGN to investigate the effect of the ADMA-DDAH1 pathway on ovarian apoptosis. Moreover, we also quantified the ADMA levels and redox status in human serum specimens, Sprague Dawley rats and KGN cells to investigate the effect of ADMA-DDAH1 on redox status and ovarian apoptosis in PCOS. We enrolled 19 women with PCOS and 17 healthy women (controls) in this study. The women with PCOS had increased serum ADMA levels and decreased glutathione peroxidase (GSH-PX) compared with the controls. In Sprague Dawley rats, 21-day DHEA treatment established PCOS and the rat contained higher ADMA levels in serum and lower DDAH1 expression in ovaries. Moreover, the PCOS rat serum and ovaries exhibited increased levels of the oxidative stress marker malondialdehyde (MDA). ADMA treatment of the KGN cells induced reactive oxygen species accumulation and led to apoptosis. Contrastingly, overexpressing DDAH1 in the KGN cells significantly decreased ADMA levels, enhanced cell viability, and inhibited oxidative stress, while the effect was inverse in DDAH1 knockdown cells. Overall, our results demonstrated that PCOS involves elevated ADMA levels and redox imbalance. The ADMA-DDAH1 pathway exerted a marked effect on oxidative stress and ovarian apoptosis in PCOS. Our findings suggested that strategies for increasing DDAH1 activity in ovarian cells may provide a novel approach for ameliorating PCOS.

Elevated VCAM-1, MCP-1 and ADMA serum levels related to pulmonary fibrosis of interstitial lung disease associated with rheumatoid arthritis

Introduction: Early diagnosis of interstitial lung disease (ILD) associated with rheumatoid arthritis (RA) constitutes a challenge for the clinicians. Pulmonary vasculopathy is relevant in the development of interstitial lung disease. Accordingly, we aimed to explore the role of vascular cell adhesion molecule-1 (VCAM-1), monocyte chemoattractant protein-1 (MCP-1) and asymmetric dimethylarginine (ADMA), key molecules in the vasculopathy, as potential biomarkers of pulmonary fibrosis in RA-ILD⁺. Methods: We included 21 RA-ILD⁺ patients and two comparative groups: 25 RA-ILD^- patients and 21 idiopathic pulmonary fibrosis (IPF) patients. Serum levels of the molecules were determined by ELISA, and mRNA expression was quantified by qPCR. Results: VCAM-1, MCP-1 and ADMA serum levels were increased in RA-ILD⁺ patients in relation to RA-ILD^- and IPF patients. Additionally, RA-ILD⁺ patients exhibited increased CCL2 (gene encoding MCP-1) and decreased PRMT1 (gene related to ADMA synthesis) mRNA expression in relation to RA-ILD^- patients. A lower expression of VCAM1, CCL2, and PRMT1 was observed in RA-ILD⁺ patients when compared with those with IPF. Furthermore, MCP-1 serum levels and PRMT1 mRNA expression were positively correlated with RA duration, and ADMA serum levels were positively associated with C-reactive protein in RA-ILD⁺ patients. Conclusion: Our study suggests that VCAM-1, MCP-1 and ADMA could be considered as useful biomarkers to identify ILD in RA patients, as well as to discriminate RA-ILD⁺ from IPF, contributing to the early diagnosis of RA-ILD⁺.

Increased Plasma L-Arginine Levels and L-Arginine/ADMA Ratios after Twelve Weeks of Omega-3 Fatty Acid Supplementation in Amateur Male Endurance Runners

It is not fully understood how supplementation with omega-3 fatty acids affects the metabolism of amino acids required for the bioavailability/synthesis of NO, i.e., L-arginine (L-arg), asymmetric dimethylarginine (ADMA), their metabolites, and the L-arg/ADMA ratio and their impact on running economy (RE) in runners. Thus, 26 male amateur endurance runners completed a twelve-week study in which they were divided into two supplemented groups: the OMEGA group (n = 14; 2234 mg and 916 mg of eicosapentaenoic and docosahexaenoic acid daily) or the MCT group (n = 12; 4000 mg of medium-chain triglycerides daily). At the same time, all participants followed an endurance training program. Before and after the 12-week intervention, blood was collected from participants at two time points (at rest and immediately post-exercise) to determine EPA and DHA in red blood cells (RBCs) and plasma levels of L-arg, ADMA, and their metabolites. RBC EPA and DHA significantly increased in the OMEGA group (p < 0.001), which was related to the resting increase in L-arg (p = 0.001) and in the L-arg/ADMA ratio (p = 0.005) with no changes in the MCT group. No differences were found in post-exercise amino acid levels. A total of 12 weeks of omega-3 fatty acid supplementation at a dose of 2234 mg of EPA and 916 mg of DHA daily increased levels of L-arg and the L-arg/ADMA ratio, which indirectly indicates increased bioavailability/NO synthesis. However, these changes were not associated with improved RE in male amateur endurance runners.

The Presence of Hyperhomocysteinemia Does Not Aggravate the Cardiometabolic Risk Imposed by Hyperuricemia in Young Individuals: A Retrospective Analysis of a Cross-Sectional Study

BACKGROUND

Little research has been conducted into the effects of the combined manifestation of hyperuricemia and hyperhomocysteinemia on cardiometabolic risk factors and markers in young subjects.

METHODS

1298 males and 1402 females, 14-to-20-year-olds, were classified into four groups: 1/normouricemic/normohomocysteinemic, 2/normouricemic/hyperhormohomocysteinemic, 3/hyperuricemic/normohomocysteinemic, and 4/hyperuricemic/hyperhomocysteinemic. Anthropometric measures, blood pressure, plasma glucose, insulin, lipids, markers of renal function, C-reactive protein, asymmetric dimethylarginine, and blood counts were determined.

RESULTS

Hyperuricemic males (but not females) had higher odds for hyperhomocysteinemia than normouricemic ones (OR: 1.8; 95% CI: 1.4-2.3; p < 0.001). Homocysteine and uric acid levels correlated directly (males: r = 0.076, females: r = 0.120; p < 0.01, both). Two-factor analysis of variance did not reveal a significant impact of hyperhomocysteinemia on any of the investigated cardiometabolic variables in females; in males, hyperuricemia and hyperhomocysteinemia showed a synergic effect on asymmetric dimethylarginine levels. Among four groups, subjects concurrently manifesting hyperuricemia and hyperhomocysteinemia did not presented the highest continuous metabolic syndrome score-a proxy measure of cardiometabolic risk; neither the multivariate regression model indicated a concurrent significant effect of uric acid and homocysteine on continuous metabolic syndrome score in either sex.

CONCLUSION

In young healthy subjects, hyperhomocysteinemia does not aggravate the negative health effects imposed by hyperuricemia.

The impact of probiotic yogurt versus ordinary yogurt on serum sTWEAK, sCD163, ADMA, LCAT and BUN in patients with chronic heart failure: a randomized, triple-blind, controlled trial

BACKGROUND

To date, no study has investigated the effects of probiotic yogurt as a functional food in patients with chronic heart failure (CHF). Therefore, the aim of this study was to compare the impact of probiotic yogurt versus ordinary yogurt on inflammatory, endothelial, lipid and renal indices in CHF patients. In this randomized, triple-blind clinical trial, 90 patients with CHF were randomly allocated into two groups to take either probiotic or ordinary yogurt for 10 weeks. Serum levels of soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK), soluble cluster of differentiation 163 (sCD163), asymmetric dimethylarginine (ADMA), and lecithin cholesterol acyltransferase (LCAT) were measured by using ELISA kits, and blood urea nitrogen (BUN) was measured by calorimetry method at baseline and at the end of trial. The P-value <0.05 was defined as statistically significant.

RESULTS

Seventy-eight patients completed the study. At the end of the intervention, the levels of sTWEAK in both groups increased significantly, and this increase was greater in the probiotic yogurt group [691.84 (335.60, 866.95)] compared to control group [581.96 (444.99, 929.40)], and the difference between the groups was statistically significant after adjusting for confounders (P-value: 0.257, adjusted P-value: 0.038). However, no significant differences were found between the groups in the cases of other study indices.

CONCLUSION

Probiotic yogurt may be useful for improving the inflammatory status in patients with CHF through increasing sTWEAK levels, however, further studies are needed in this area. © 2022 Society of Chemical Industry.

Predictive markers in chronic kidney disease

Chronic kidney disease (CKD) is defined by gradual deterioration of the renal parenchyma and decline of functioning nephrons. CKD is now recognized as a distinct risk factor for cardiovascular disease (CVD). This risk rises in tandem with the decline in kidney function and peaks at the end-stage. It is important to identify individuals with CKD who are at a higher risk of advancing to end-stage renal disease (ESRD) and the beginning of CVD. This will enhance the clinical benefits and so that evidence-based therapy may be started at the initial stages for those individuals. A promising biomarker must represent tissue damage, and be easy to detect using non-invasive methods. Current CKD progression indicators have difficulties in reaching this aim. Hence this review presents an update on markers studied in the last decade, which help in the prediction of CKD progression such as neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, urinary liver-type fatty acid-binding protein, cystatin-C, asymmetric dimethylarginine, symmetric dimethylarginine, endotrophin, methylglyoxal, sclerostin, uric acid, and miRNA-196a. Additional research is needed to determine the predictive usefulness of these indicators in clinical samples for disease development. Their utility as surrogate markers need to be explored further for the early identification of CKD progression.

Periodontal Treatment Reduces Circulating Pro-Inflammatory Cytokine and Chemokine Levels in African American HIV+ Individuals with Virological Suppression

INTRODUCTION

Periodontal Disease (PD), a chronic inflammatory disease, is highly prevalent among Persons Living With HIV (PLWH) and is characterized by microbial symbiosis and oxidative stress. Our hypothesis stipulates that periodontal therapy attenuates systemic inflammatory and bacterial burden while improving periodontal status in PLWH.

METHODS

Sixteen African Americans (AA) with suppressed HIV viremia on long-term Antiretroviral Therapy (ART) were recruited to this study. Participants were placed into two groups, based on their dental care status: group 1 (In-Care, IC) and group 2 (Out of Care, OC). Periodontal health was investigated at baseline, 3 months, 6 months, and 12 months. Cytokine/chemokines, microbial phyla, and Asymmetric Dimethylarginine (ADMA, a marker for endothelial cell dysfunction) levels were assessed in the serum. Statistical comparisons between groups and at different visits were performed using multiple comparison tests.

RESULTS

Across longitudinal visits, periodontal treatment significantly reduced the levels of several cytokines and chemokines. At baseline, the out of care group had significantly higher blood levels of ADMA and actinobacteria than the IC group. Periodontal treatment significantly altered the abundance of circulating genomic bacterial DNA for various phyla in out of care group.

CONCLUSIONS

Periodontal treatment interventions effectively attenuated circulating pro-inflammatory cytokines and altered microbial translocation, both critical drivers of systemic inflammation in PLWH.

TNF-α Inhibitors in Combination with MTX Reduce Circulating Levels of Heparan Sulfate/Heparin and Endothelial Dysfunction Biomarkers (sVCAM-1, MCP-1, MMP-9 and ADMA) in Women with Rheumatoid Arthritis

Sulfated glycosaminoglycans (sGAGs) are likely to play an important role in the development and progression of rheumatoid arthritis (RA)-associated atherosclerosis. The present study investigated the effect of anti-tumor necrosis factor-α (anti-TNF-α) therapy in combination with methotrexate on plasma sGAG levels and serum markers of endothelial dysfunction. Among sGAG types, plasma chondroitin/dermatan sulfate (CS/DS) and heparan sulfate/heparin (HS/H) were characterized using electrophoretic fractionation. Serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1), monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase-9 (MMP-9) and asymmetric dimethylarginine (ADMA) were measured by immunoassays. The measurements were carried out four times: at baseline and after 3, 9 and 15 months of anti-TNF-α therapy. All analyzed parameters, excluding ADMA, were significantly elevated in patients with RA before the implementation of biological therapy compared to healthy subjects. Performed anti-TNF-α treatment led to a successive decrease in HS/H levels toward normal values, without any effect on CS/DS levels in female RA patients. The treatment was also effective at lowering the serum levels of sVCAM-1, MCP-1, MMP-9 and ADMA. Moreover, a significant positive correlation was found between the circulating HS/H and the 28 joint disease activity score based on the erythrocyte sedimentation rate (DAS28-ESR, r = 0.408; p <0.05), MCP-1 (r = 0.398; p <0.05) and ADMA (r = 0.396; p <0.05) in patients before the first dose of TNF-α inhibitor. In conclusion, a beneficial effect of anti-TNF-α therapy on cell-surface heparan sulfate proteoglycans (HSPGs)/HS turnover and endothelial dysfunction was observed in this study. This was manifested by a decrease in blood HS/H levels and markers of endothelial activation, respectively. Moreover, the decrease in the concentration of HS/H in the blood of patients during treatment, progressing with the decline in disease activity, indicates that the plasma HS/H profile may be useful for monitoring the efficacy of anti-TNF-α treatment in patients with RA.

The interplay between exposure to PAHs and MTHFR C677T polymorphism on cardiovascular risk biomarkers in Mexican women

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Environmental and genetic factors are recognized as risk determinants in the onset and development of CVDs. However, the interaction between both factors on CVDs risk is not still completely clarified. Therefore, the objective of this study was to evaluate the effect of the interaction between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and polycyclic aromatic hydrocarbon (PAH) exposure (gene-environment interaction) on cardiovascular risk biomarkers in Mexican women. A cross-sectional study was completed with the participation of 390 healthy women. For all enrolled women, anthropometric measurements, serum biochemical analyses, atherogenic indexes, and serum concentrations of biomolecules used as CVD risk biomarkers were obtained. 1-Hydroxypyrene (1-OHP) was measured in urine, as an exposure biomarker of PAHs. The mean urinary level of 1-OHP in the assessed population was 1.23 ± 1.40 μmol/mol creatinine. The allelic frequency (MTHFR C677T polymorphism) identified in the registered individuals was 68.0% for the mutant allele (T-allele). Significant positive associations were detected between urinary 1-OHP levels and serum asymmetric dimethylarginine (ADMA) concentrations (p < 0.05) and atherogenic index of plasma (AIP) values (p < 0.05). Also, women with the TT genotype of the MTHFR C677T enzyme have the highest serum ADMA levels (p < 0.05) and AIP values (p < 0.05) compared to women grouped as CC genotype and CT genotype. Besides, the findings in this study suggest an interaction between environmental (PAHs exposure) and genetic (MTHFR C677T polymorphism) factors on cardiovascular risk markers (ADMA and AIP). According to the usefulness of AIP and ADMA, an increased cardiovascular risk is notable in highly exposed individuals to PAHs with the polymorphic genotype (TT) of the MTHFR enzyme. Therefore, intervention programs in the target communities are required to diminish the cardiovascular risk of the assessed individuals.

Role of ADMA/DDAH-1 and iNOS/eNOS signaling in the gastroprotective effect of tadalafil against indomethacin-induced gastric injury

Non-steroidal anti-inflammatory drugs (NSAIDs)-induced gastric ulcers represent a significant clinical concern and adversely affect the quality of life. Inducible nitric oxide synthase/endothelial nitric oxide synthase (iNOS/eNOS) and asymmetric dimethylarginine/ dimethylarginine dimethylaminohydrolase-1 (ADMA/DDAH-1) signaling are key players in gastric ulcer pathogenesis. This work was planned to explore the role of iNOS/eNOS and ADMA/DDAH-1 signaling in rats with indomethacin-induced gastric ulcer, as potential pathways for the gastro-protective effect of tadalafil. Split into 5 separate groups, rats were assigned to control, tadalafil (10 mg/kg, p.o), indomethacin (single oral dose of 60 mg/kg), indomethacin + pantoprazole (40 mg/kg, p.o), and indomethacin + tadalafil (10 mg/kg, p.o). The results indicated that pretreatment with tadalafil significantly reduced ulcer index (UI), increased preventive index (PI), and counteracted indomethacin-induced histopathological aberrations. Tadalafil significantly reduced the gastric content of NO while it significantly elevated that of GSH and enhanced SOD activity. It significantly reduced the gastric expression of TNF-α and ADMA while it significantly elevated that of COX-2, PGE-2, and DDAH-1. Western blot analysis revealed that pretreatment with tadalafil significantly reduced iNOS protein expression while it significantly elevated that of eNOS. Collectively, these data suggest that tadalafil exerts potential protective effect against indomethacin-induced ulcer through suppression of inflammation, attenuation of oxidative stress, and boosting of antioxidants. Moreover, tadalafil protective effects are mediated via upregulation of PGE-2 with modulating the signaling pathways of ADMA/DDAH-1, and iNOS/eNOS. As a result, the current evidence corroborates the use of tadalafil in controlling gastric ulcers and preventing NSAID gastric side effects.

Screening of commonly prescribed drugs for effects on the CAT1-mediated transport of L-arginine and arginine derivatives

The cationic amino acid transporter 1 (CAT1/SLC7A1) plays a key role in the cellular uptake or export of l-arginine and some of its derivatives. This study investigated the effect of 113 chemically diverse and commonly used drugs (at 20 and 200 µM) on the CAT1-mediated cellular uptake of l-arginine, l-homoarginine, and asymmetric dimethylarginine (ADMA). Twenty-three (20%) of the tested substances showed weak inhibitory or stimulatory effects, but only verapamil showed consistent inhibitory effects on CAT1-mediated transport of all tested substrates.

Lean insulin-resistant young adults display increased cardiometabolic risk: A retrospective cross-sectional study

AIM

We investigated whether lean insulin-resistant individuals manifest increased cardiometabolic risk.

METHODS

2,341 (51.8% females) healthy 16-23-year-old subjects were categorized as lean or overweight/obese; and insulin-sensitive or insulin-resistant, and compared.

RESULTS

In both sexes, lean insulin-sensitive and insulin-resistant subjects displayed similar measures of obesity (e.g., males, waist-to-height ratio: lean insulin-sensitive: 0.42 ± 0.03, lean insulin-resistant: 0.43 ± 0.03, overweight/obese insulin-sensitive: 0.49 ± 0.05, overweight/obese insulin-resistant: 0.53 ± 0.06). Lean insulin-sensitive individuals were more insulin-sensitive compared with their overweight/obese peers; insulin-resistant groups presented similar insulin-sensitivity (males, the Quantitative insulin-sensitivity check index (QUICKI): lean insulin-sensitive: 0.354 ± 0.022, lean insulin-resistant: 0.304 ± 0.013, overweight/obese insulin-sensitive: 0.343 ± 0.019, overweight/obese insulin-resistant: 0.299 ± 0.015). The two-factor analysis of variance indicated an independent effect of insulin sensitivity, overweight/obesity, and their interaction on the continuous metabolic syndrome score (p < 0.001, all; males, lean insulin-sensitive: 1.87 ± 0.35, lean insulin-resistant: 2.14 ± 0.42, overweight/obese insulin-sensitive: 2.15 ± 0.40, overweight/obese insulin-resistant: 2.75 ± 0.69). C-reactive protein, leukocyte count, and glomerular filtration rate in both sexes; uric acid, asymmetric dimethyl-arginine, and soluble vascular adhesion protein-1 in males; and soluble receptor for advanced glycation end-products in females were independently associated with insulin resistance. Among phenotypes associated with low QUICKI, the distribution of insulin-resistant individuals was random.

CONCLUSION

Later clinical consequences of insulin resistance in lean subjects remain to be elucidated in longitudinal studies.

Plasma Arginine and Citrulline are Elevated in Diabetic Retinopathy

PURPOSE

To determine if plasma levels of six arginine-related and citrulline-related metabolites (arginine, citrulline, asymmetric dimethylarginine [ADMA], ornithine, proline, and argininosuccinate) differ between patients with type 2 diabetes and diabetic retinopathy (DR) and type 2 diabetic controls or between patients with proliferative DR (PDR) and non-proliferative DR (NPDR).

DESIGN

Cross-sectional study.

METHODS

Adults with type 2 diabetes were recruited from the Vanderbilt Eye Institute. Exclusion criteria included non-diabetic retinal disease. Plasma metabolite levels were quantified in 159 diabetic controls and 156 DR patients (92 NPDR, 64 PDR) using isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). Metabolite levels were compared using Wilcoxon Rank Sum test and logistic regressions adjusting for age, sex, hemoglobin A1c, diabetes duration, statin use, and angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker use. A secondary analysis that included creatinine in the regression model was performed for the subset of patients with available creatinine values (135 diabetic controls, 100 DR patients [58 NPDR, 42 PDR]).

RESULTS

Multivariable logistic regression analyses determined that arginine (OR = 1.20, [1.06-1.38], P = .0067) and citrulline (OR = 1.53, [1.20-1.98], P = .0025) were significantly elevated in DR patients compared to diabetic controls. While ADMA differed between NPDR and PDR patients in the primary analysis (OR = 1.56, [1.15-2.16], P = .0051), it was not significantly different when adjusting for creatinine (OR = 1.30, [0.90-1.91], P = .15).

CONCLUSIONS

Plasma arginine and citrulline were significantly elevated in type 2 diabetic patients with DR compared to diabetic controls. None of the tested metabolites significantly differed between NPDR and PDR patients in the adjusted analysis.

Effects of treatment with SGLT-2 inhibitors on arginine-related cardiovascular and renal biomarkers

BACKGROUND

In patients with type 2 diabetes (T2D) sodium-glucose cotransporter 2 (SGLT-2) inhibitors improve glycaemic control as well as cardiovascular and renal outcomes. Their effects on L-arginine (Arg) related risk markers asymmetric and symmetric dimethylarginine (ADMA and SDMA) and the protective biomarker L-homoarginine (hArg) linking T2D to cardiovascular and renal disease have not yet been reported.

METHODS

Plasma and 24-h urine samples taken before and after 6 weeks of treatment were available from two prospective, randomized, double-blind, placebo-controlled, cross-over trials with empagliflozin (71 patients analyzed, NCT02471963) and dapagliflozin (59 patients analyzed, NCT02383238). In these samples, concentrations of hArg, Arg, ADMA, SDMA, and creatinine were determined by liquid-chromatography coupled to tandem mass-spectrometry. Additionally, intraindividual changes of the biomarkers in plasma were correlated with intraindividual changes of clinical parameters.

RESULTS

Treatment with empagliflozin and dapagliflozin was associated with a reduction of plasma hArg by 17.5% and 13.7% (both p < 0.001), respectively, and increase in plasma SDMA concentration of 6.7% and 3.6%, respectively (p < 0.001 and p < 0.05), while plasma Arg and ADMA concentrations were not significantly altered. 24-h urinary excretion of ADMA was reduced by 15.2% after treatment with empagliflozin (p < 0.001) but not after dapagliflozin treatment, while excretion of the other markers was not significantly altered. Renal clearance of SDMA was reduced by 9.1% and 3.9% for both drugs (both p < 0.05). A reduction in ADMA clearance was observable after empagliflozin treatment only (- 15.5%, p < 0.001), but not after dapagliflozin. Renal clearance of hArg and Arg was not significantly altered. Treatment effects on L-arginine related biomarkers were not constantly correlated with effects on glycated hemoglobin, fasting plasma glucose, body mass index, and systolic blood pressure.

CONCLUSIONS

Treatment with SGLT-2 inhibitors has divergent effects on Arg-related biomarkers and could affect risk estimates associated with these markers. The observed effects are unlikely to explain the known cardiovascular and renal benefits of treatment with empagliflozin or dapagliflozin but still may indicate new therapeutic approaches in patients treated with SGLT-2 inhibitors. Trial registration http://www.clinicaltrials.gov : NCT02471963 (registered 15th June 2015, retrospectively registered) and NCT02383238.

Metabolites of L-ARG in Exhaled Breath Condensate and Serum Are Not Biomarkers of Bronchial Asthma in Children

(1) Background: L-arginine (L-ARG) and its metabolites are involved in some aspects of asthma pathogenesis (airway inflammation, oxidative stress, bronchial responsiveness, collagen deposition). Published data indicate that lungs are a critical organ for the regulation of L-ARG metabolism and that alterations in L-ARG metabolism may be significant for asthma. The aim of this study was to assess the levels of L-ARG and its metabolites in pediatric patients with asthma in serum and exhaled breath condensate (EBC) by mass spectrometric analysis and compare them with non-asthmatic children. (2) Methods: Sixty-five children (37 pediatric patients with bronchial asthma and 28 healthy control subjects) aged 6–17 participated in the study. All participants underwent a clinical visit, lung tests, allergy tests with common aeroallergens, and serum and EBC collection. The levels of biomarkers were determined in both serum and EBC. Analytical chromatography was conducted using an Acquity UPLC system equipped with a cooled autosampler and an Acquity HSS T3 column. Mass spectrometric analysis was conducted using the Xevo G2 QTOF MS with electrospray ionization (ESI) in positive ion mode. (3) Results: Asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) levels in serum and EBC did not differ significantly in asthmatic children and healthy control subjects. We found no correlation between forced expiratory volume in one second (FEV1) and L-ARG and its metabolites, as well as between interleukin-4 (IL-4) serum level and L-ARG and its metabolites. Concentrations of ADMA, SDMA, citrulline (CIT), and ornithine (ORN) were higher in serum than EBC in asthmatics and non-asthmatics. By contrast, concentrations of dimethylarginine (DMA) were higher in EBC than serum. ADMA/L-ARG, SDMA/L-ARG, and DMA/L-ARG ratios were significantly higher in EBC than in serum in asthmatics and in non-asthmatics. (4) Conclusions: Serum and EBC concentrations of L-ARG and its metabolites were not an indicator of pediatric bronchial asthma in our study.

Inhibition of miR-21 improves pulmonary vascular responses in bronchopulmonary dysplasia by targeting the DDAH1/ADMA/NO pathway

miR-21 has been confirmed to be overexpressed in neonatal rat lungs with hyperoxia-mediated bronchopulmonary dysplasia (BPD). The specific function of miR-21 in BPD is still unclear. We established the hyperoxia-induced BPD rat model in vivo and the hyperoxia-induced pulmonary microvascular endothelial cells (PMVECs) model in vitro. Transwell assay was utilized to detect the migratory capability of PMVECs. Tube formation assay was utilized to measure angiogenesis ability. ELISA was utilized to test nitric oxide (NO) production and the intracellular and extracellular Asymmetric Dimethylarginine (ADMA) concentration. Furthermore, the interaction between miR-21 and dimethylarginine dimethylaminohydrolase 1 (DDAH1) was evaluated using luciferase reporter assay. We found that miR-21 expression in PMVECs was increased by hyperoxia stimulation. Inhibition of miR-21 improved the migratory and angiogenic activities of PMVECs and overexpression of miR-21 exerted the opposite effects. Furthermore, knockdown of miR-21 increased NO production and decreased intracellular and extracellular ADMA concentration in hyperoxia-treated PMVECs. Next we proved that miR-21 could bind to DDAH1 and negatively regulate its expression. Rescues assays showed that DDAH1 knockdown reversed the effects of miR-21 depletion on hyperoxia-mediated PMVEC functions, NO production, and ADMA concentration. Importantly, miR-21 downregulation restored alveolarization and vascular density in BPD rats. This study demonstrates that inhibition of miR-21 improves pulmonary vascular responses in BPD by targeting the DDAH1/ADMA/NO pathway.

Developing a robust, fast and reliable measurement method for the analysis of methylarginine derivatives and related metabolites

Background

Nitric oxide (NO) plays an important role in endothelial homeostasis. Asymmetric dimethyl arginine (ADMA), L-N monomethyl arginine (L-NMMA) and symmetric dimethyl arginine (SDMA), which are derivatives of methylarginine, directly or indirectly reduce NO production. Therefore, these metabolites are an important risk factor for various diseases, including cardiovascular diseases. Numerous methods have been developed for the measurement of methylarginine derivatives, but various difficulties have been encountered. This study aimed to develop a reliable, fast and cost-effective method for the analysis and measurement of methylarginine derivatives (ADMA, SDMA, L-NMMA) and related metabolites (arginine, citrulline, homoarginine, ornithine), and to validate this method according to Clinical and Laboratory Standards Institute (CLSI) protocols.

Methods

For the analysis of ADMA, SDMA, L-NMMA, arginine, homoarginine, citrulline, ornithine, 200 Âµl of serum were precipitated with methanol, and subsequently derivatized with a butanol solution containing 5% acetyl chloride. Butyl derivatives were separated using a C18 reverse phase column with a 5 min run time. Detection of analytes was achieved by utilising the specific fragmentation patterns identified through tandem mass spectrometry.

Results

The method was linear for ADMA, SDMA, L-NMMA, ornithine, arginine, homoarginine and citrulline in the ranges of 0.023–6.0, 0.021–5.5, 0.019–5.0, 0.015–250, 0.015–250, 0.019–5 and 0.015–250 µM, respectively. The inter-assay CV% values for all analytes was less than 9.8%.

Conclusions

Data obtained from method validation studies shows that the developed method is highly sensitive, precise and accurate. Short analysis time, cost-effectiveness, and multiplexed analysis of these metabolites, with the same pretreatment steps, are the main advantages of the method.

Effect of Hyperbaric Oxygenation on Blood Cytokines and Arginine Derivatives; No Evidence for Induction of Inflammation or Endothelial Injury

(1) Background: Hyperbaric oxygen therapy (HBOT) uses 100% oxygen delivered at 1.5-3 times the atmospheric pressure in a specialised chamber to achieve supraphysiological oxygen tension in blood and tissues. Besides its target, HBOT may affect inflammation, endothelial function or angiogenesis. This study analysed the effect of HBOT on blood concentrations of factors that may affect these processes in patients with necrotizing soft-tissue infections (NSTI), aseptic bone necrosis (ABN) and idiopathic sudden sensory neural hearing loss (ISSNHL). (2) Methods: Concentrations asymmetric dimethylarginine (ADMA) and other arginine derivatives were measured with liquid chromatography/mass spectrometry, whereas ELISA was used to quantitate vascular endothelial growth factor (VEGF) and cytokines (IL-1, IL-4, IL-6, IL-10, TGF-β) before and after HBOT in 80 patients (NSTI n = 21, ISSNHL n = 53, ABN n = 6). (3) Results: While some differences were noted between patient groups in ADMA and other arginine derivatives as well as in cytokine concentrations, HBOT did not affect any of these parameters. (4) Conclusions: While cytokines and arginine derivatives concentrations were modified by underlying pathology, hyperbaric oxygenation did not immediately modify it suggesting that it is neutral for inflammation and is not inducing endothelial injury.

Decreased nitric oxide content mediated by asymmetrical dimethylarginine and protein l-arginine methyltransferase 3 in macrophages induces trophoblast apoptosis: a potential cause of recurrent miscarriage

STUDY QUESTION

Is the protein l-arginine methyltransferase 3 (PRMT3)/asymmetrical dimethylarginine (ADMA)/nitric oxide (NO) pathway involved in the development of recurrent miscarriage (RM), and what is the potential mechanism?

SUMMARY ANSWER

Elevated levels of PRMT3 and ADMA inhibit NO formation in the decidua, thereby impairing the functions of trophoblast cells at the maternal-foetal interface.

WHAT IS KNOWN ALREADY

Decreased NO bioavailability is associated with RM. ADMA, an endogenous inhibitor of nitric oxide synthase (NOS), is derived from the methylation of protein arginine residues by PRMTs and serves as a predictor of mortality in critical illness.

STUDY DESIGN, SIZE, DURATION

A total of 145 women with RM and 149 healthy women undergoing elective termination of an early normal pregnancy were enrolled. Ninety-six female CBA/J, 24 male DBA/2 and 24 male BALB/c mice were included. CBA/J × DBA/2 matings represent the abortion group, while CBA/J × BALB/c matings represent the normal control group. The CBA/J pregnant mice were then categorised into four groups: (i) normal + vehicle group (n = 28), (ii) abortion + vehicle group (n = 28), (iii) normal + SGC707 (a PRMT3 inhibitor) group (n = 20) and (iv) abortion + SGC707 group (n = 20). All injections were made intraperitoneally on Days 0.5, 3.5 and 6.5 of pregnancy. Decidual tissues were collected on Days 8.5, 9.5 and 10.5 of gestation. The embryo resorption rates were calculated on Day 9.5 and Day 10.5 of gestation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

NO concentration, ADMA content, NOS activity, expression levels of NOS and PRMTs in decidual tissues were determined using conventional assay kits or western blotting. PRMT3 expression was further analysed in decidual stromal cells, macrophages and natural killer cells. A co-culture system between decidual macrophages (DMs) and HTR-8/SVneo trophoblasts was constructed to study the roles of the PRMT3/ADMA/NO signalling pathway. Trophoblast apoptosis was analysed via Annexin V-fluorescein isothiocyanate/propidium iodide staining. CBA/J × DBA/2 mouse models were used to investigate the effects of SGC707 on embryo resorption rates.

MAIN RESULTS AND THE ROLE OF CHANCE

Our results show that NO concentration and NOS activity were decreased, but ADMA content and PRMT3 expression were increased in the decidua of RM patients. Moreover, compared with the normal control subjects, PRMT3 expression was significantly up-regulated in the macrophages but not in the natural killer cells or stromal cells of the decidua from RM patients. The inhibition of PRMT3 results in a significant decrease in ADMA accumulation and an increase in NO concentration in macrophages. When co-cultured with DMs, which were treated with SGC707 and ADMA, trophoblast apoptosis was suppressed and induced, respectively. In vivo experiments revealed that the administration of SGC707 reduced the embryo resorption rate of CBA/J × DBA/2 mice.

LIMITATIONS, REASONS FOR CAUTION

All sets of experiments were not performed with the same samples. The main reason is that each tissue needs to be reserved for clinical diagnosis and only a small piece of each tissue can be cut and collected for this study.

WIDER IMPLICATIONS OF THE FINDINGS

Our results indicate that the PRMT3/ADMA/NO pathway is a potential marker and target for the clinical diagnosis and therapy of RM.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Key Research and Development Program of China (2017YFC1001401), National Natural Science Foundation of China (81730039, 82071653, 81671460, 81971384 and 82171657) and Shanghai Municipal Medical and Health Discipline Construction Projects (2017ZZ02015). The authors have declared no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Nitric Oxide-Dependent Mechanisms Underlying MK-801- or Scopolamine-Induced Memory Dysfunction in Animals: Mechanistic Studies

MK-801, an NMDA receptor antagonist, and scopolamine, a cholinergic receptor blocker, are widely used as tool compounds to induce learning and memory deficits in animal models to study schizophrenia or Alzheimer-type dementia (AD), respectively. Memory impairments are observed after either acute or chronic administration of either compound. The present experiments were performed to study the nitric oxide (NO)-related mechanisms underlying memory dysfunction induced by acute or chronic (14 days) administration of MK-801 (0.3 mg/kg, i.p.) or scopolamine (1 mg/kg, i.p.). The levels of L-arginine and its derivatives, L-citrulline, L-glutamate, L-glutamine and L-ornithine, were measured. The expression of constitutive nitric oxide synthases (cNOS), dimethylaminohydrolase (DDAH1) and protein arginine N-methyltransferases (PMRTs) 1 and 5 was evaluated, and the impact of the studied tool compounds on cGMP production and NMDA receptors was measured. The studies were performed in both the cortex and hippocampus of mice. S-nitrosylation of selected proteins, such as GLT-1, APP and tau, was also investigated. Our results indicate that the availability of L-arginine decreased after chronic administration of MK-801 or scopolamine, as both the amino acid itself as well as its level in proportion to its derivatives (SDMA and NMMA) were decreased. Additionally, among all three methylamines, SDMA was the most abundant in the brain (~70%). Administration of either compound impaired eNOS-derived NO production, increasing the monomer levels, and had no significant impact on nNOS. Both compounds elevated DDAH1 expression, and slight decreases in PMRT1 and PMRT5 in the cortex after scopolamine (acute) and MK-801 (chronic) administration were observed in the PFC, respectively. Administration of MK-801 induced a decrease in the cGMP level in the hippocampus, accompanied by decreased NMDA expression, while increased cGMP production and decreased NMDA receptor expression were observed after scopolamine administration. Chronic MK-801 and scopolamine administration affected S-nitrosylation of GLT-1 transport protein. Our results indicate that the analyzed tool compounds used in pharmacological models of schizophrenia or AD induce changes in NO-related pathways in the brain structures involved in cognition. To some extent, the changes resemble those observed in human samples.

Bariatric Surgery Improves the Atherogenic Profile of Circulating Methylarginines in Obese Patients: Results from a Pilot Study

Bariatric surgery improves obesity-related comorbidities. Methylarginines are biomarkers of cardiometabolic risk, liver steatosis, and insulin resistance. Here, we aimed to investigate methylarginines in obese patients undergoing bariatric surgery and compared them to age- and sex-matched healthy subjects. Thirty-one obese patients who underwent bariatric surgery and 31 healthy individuals were used for this retrospective study. The basal serum methylarginine levels were determined in the healthy individuals and the obese patients, before surgery and 6 and 12 months after surgery, by mass spectrometry. Compared with the healthy individuals, the obese patients displayed elevated monomethylarginine (mean change: +95%, p < 0.001), asymmetric-dimethylarginine (+105%, p < 0.001), symmetric-dimethylarginine (+25%, p = 0.003), and dimethylguanidino valerate (+32%, p = 0.008) concentrations. Bariatric surgery durably reduced the body mass index by 28% (12 months, 95%CI: 24–33, p = 0.002) and improved plasma lipids, insulin resistance, and liver function. Bariatric surgery reduced the serum levels of monomethylarginine and asymmetric-dimethylarginine by 12% (95%CI: 6–17) and 36% (95%CI: 27–45) (12 months, p = 0.003), respectively, but not symmetric-dimethylarginine or dimethylguanidino valerate. The monomethylarginine and asymmetric-dimethylarginine concentrations were strongly correlated with markers of dyslipidemia, insulin resistance, and a fatty liver. Serum dimethylguanidino valerate was primarily correlated with glycemia and renal function, whereas serum symmetric-dimethylarginine was almost exclusively associated with renal function. In conclusion, the monomethylarginine and asymmetric-dimethylarginine levels are efficiently decreased by bariatric surgery, leading to a reduced atherogenic profile in obese patients. Methylarginines follow different metabolic patterns, which could help for the stratification of cardiometabolic disorders in obese patients.

Study of arginine metabolism in medication overuse chronic migraine: possible defect in NO synthesis

BACKGROUND AND AIM

The pathogenesis of the pain that occurs in episodic migraine attack is due to the activation of the trigeminal system's first neuron receptors located on vessel wall. The release from the endothelium of nitric oxide, a product of arginine metabolism, causes vasodilation and stretching of the vascular trigeminal system and promotes pain. It is unknown whether this same metabolic event is involved in the pain accompanying chronic migraine. To understand the possible role of arginine in the pathogenesis of chronic migraine patients, we evaluated the metabolism of arginine in plasma of chronic migraine and control subjects.

METHODS

We evaluated the metabolism of arginine in a group of patients affected by chronic migraine. Quantification of arginine, ornithine, citrulline, monomethyl arginine (NMMA), dimethylarginines (ADMA, SDMA), and tyramine was performed by ultra-performance liquid chromatography coupled with a triple quadrupole mass spectrometer.

RESULTS

Chronic migraine patients showed low plasma levels of arginine, significantly elevated levels of ornithine, ADMA, and NMMA whereas the levels of citrulline and SDMA were in the range of controls.

CONCLUSIONS

The elevated levels of ADMA and NMMA, inhibitors of nitric oxide synthase, suggest that the metabolism of arginine may be inhibited with a possible reduction of NO release in the circulation of chronic patients. This suggests that the origin of pain may not be related to the vasodilation of trigeminal vascular system that occurs in episodic migraine patients.

Endothelial dysfunction biomarkers in sickle cell disease: is there a role for ADMA and PAI-1?

Within the spectrum of sickle cell disease (SCD) are sickle cell anemia (SCA), presence of hemoglobin SS (HbSS), hemoglobin SC disease (HbSC), and sickle cell β-thalassemia (Sβ-thal). Asymmetric dimethylarginine (ADMA) competitively inhibits the binding of arginine to NOS, reducing NO production. In patients with HbSS, increased levels of ADMA have been reported, as well as changes in many hemostatic biomarkers, including the plasminogen activator inhibitor type 1 (PAI-1). We hypothesized that high levels of ADMA and PAI-1 may be associated with more severe SCD. Thus, ADMA and PAI-1 levels were determined in 78 individuals including 38 adult patients with SCD and 40 control subjects. Higher levels of ADMA were shown in HbSS and Sβ-thal patients compared to controls. Concerning PAI-1, all patients showed high levels of PAI-1 compared to controls. As a role of NO in the pathogenesis of SCD has already been established, we concluded that high levels of ADMA should compromise, at least in part, NO synthesis, resulting in endothelial dysfunction. Elevated plasma levels of PAI-1 in all patients may indicate not only endothelial dysfunction but also a hypofibrinolytic state favoring thrombotic complications. Finally, high levels of ADMA and PAI-1 may be associated with more severe SCD.