Asymmetric dimethylarginine (ADMA), a potent endogenous nitric oxide synthase (NOS) inhibitor, is increased in idiopathic pulmonary arterial hypertension and associated with unfavorable outcome.
Chronic thromboembolic pulmonary hypertension (CTEPH), although principally amenable to surgical removal of major pulmonary arterial obstructions by pulmonary endarterectomy, may show a small-vessel pulmonary arteriopathy similar to idiopathic pulmonary arterial hypertension. We hypothesized that ADMA plasma levels are increased in patients with CTEPH.
We measured ADMA by high-performance liquid chromatography at the time of diagnosis in 135 patients with CTEPH. Inoperability in 66 patients was based on an imbalance between severity of pulmonary hypertension and morphologic lesions.
ADMA plasma levels were significantly elevated in patients, compared with 40 matched control subjects (0.62 [0.51-0.73] vs. 0.51 [0.45-0.6] micromol/L, P = 0.0002). At baseline, ADMA plasma concentrations correlated with mixed venous saturation (r = -0.25, P = 0.005), right atrial pressure (r = 0.35, P < 0.0001), and cardiac index (r = -0.21, P = 0.01). Patients who underwent surgery demonstrated lower ADMA levels at baseline than inoperable patients (0.60 [0.5-0.68] vs. 0.63 [0.53-0.85] micromol/L, P = 0.02), with a further decrease 12 +/- 1 months after pulmonary endarterectomy (P = 0.02). Endothelial NOS expression in endothelial cells was low in patients with elevated ADMA plasma levels. Survival of patients with ADMA plasma levels >/= 0.64 micromol/L was worse than in patients with ADMA plasma levels < 0.64 micromol/L.
ADMA plasma levels correlate with the severity of pulmonary vascular disease and predict outcome in patients with CTEPH. Measurement of ADMA plasma levels may be useful for estimating the degree of small-vessel arteriopathy in CTEPH.
"Indeed, a distinct class of emerging therapies for PH is based upon the antagonistic actions of asymmetric dimethylarginine (ADMA) regulating NO production (137). Elevated plasma ADMA has been shown to correlate to severity of idiopathic (138) and chronic thromboembolic PH in adults (139), and in children with congenital heart disease (140) and sickle cell disease with PH (141). Moreover, in one study of systemic heart failure associated with pulmonary venous hypertension, exhaled NO levels were in higher in hypertensives, but NO did not correlate to increased plasma ADMA (142). "
[Show abstract][Hide abstract] ABSTRACT: Therapeutic approaches in pediatric pulmonary arterial hypertension (PAH) are based primarily on clinician experience, in contrast to the evidence-based approach in adults with pulmonary hypertension. There is a clear and present need for non-invasive and objective biomarkers to guide the accurate diagnosis, treatment, and prognosis of this disease in children. The multifaceted spectrum of disease, clinical presentation, and association with other diseases makes this a formidable challenge. However, as more progress is being made in the understanding and management of adult PAH, the potential to apply this knowledge to children has never been greater. This review explores the state of the art with regard to non-invasive biomarkers in PAH, with an eye toward those adult PAH biomarkers potentially suitable for application in pediatric PAH.
Frontiers in Pediatrics 02/2014; 2:7. DOI:10.3389/fped.2014.00007
"A product of protein arginine methylation, ADMA, is a naturally occurring nitric oxide synthase (NOS) inhibitor . Elevated ADMA concentrations have been detected in the plasma of patients with idiopathic (i) PAH [109–111], CTEPH , PAH-related sickle cell disease  and systemic sclerosis , suggesting a strong association of circulating dimethylarginine levels with PH pathogenesis. It remains unclear which DDAH or PRMT isoforms control ADMA tissue and plasma levels under those pathological conditions. "
[Show abstract][Hide abstract] ABSTRACT: Protein arginine methylation is a novel posttranslational modification that plays a pivotal role in a variety of intracellular events, such as signal transduction, protein-protein interaction and transcriptional regulation, either by the direct regulation of protein function or by metabolic products originating from protein arginine methylation that influence nitric oxide (NO)-dependent processes. A growing body of evidence suggests that both mechanisms are implicated in cardiovascular and pulmonary diseases. This review will present and discuss recent research on PRMTs and the methylation of non-histone proteins and its consequences for the pathogenesis of various lung disorders, including lung cancer, pulmonary fibrosis, pulmonary hypertension, chronic obstructive pulmonary disease and asthma. This article will also highlight novel directions for possible future investigations to evaluate the functional contribution of arginine methylation in lung homeostasis and disease.
International Journal of Molecular Sciences 12/2012; 13(10):12383-400. DOI:10.3390/ijms131012383 · 2.86 Impact Factor
"Abnormal NO metabolism accompanied by administration of ADMA has been described in patients with pulmonary hypertension associated with advanced systolic heart failure  and Down syndrome . Elevated ADMA concentrations are also associated with hemodynamic parameters and prognosis in idiopathic  and chronic thromboembolic pulmonary hypertension . With regards to SSc, it has been reported that ADMA is increased in patients with echocardiographically defined pulmonary hypertension  and it is correlated with systolic pulmonary artery pressure and functional capacity . "
[Show abstract][Hide abstract] ABSTRACT: The last few decades have witnessed an increased life expectancy of patients suffering with systemic rheumatic diseases, mainly due to improved management, advanced therapies and preventative measures. However, autoimmune disorders are associated with significantly enhanced cardiovascular morbidity and mortality not fully explained by traditional cardiovascular disease (CVD) risk factors. It has been suggested that interactions between high-grade systemic inflammation and the vasculature lead to endothelial dysfunction and atherosclerosis, which may account for the excess risk for CVD events in this population. Diminished nitric oxide synthesis-due to down regulation of endothelial nitric oxide synthase-appears to play a prominent role in the imbalance between vasoactive factors, the consequent impairment of the endothelial hemostasis and the early development of atherosclerosis. Asymmetric dimethylarginine (ADMA) is one of the most potent endogenous inhibitors of the three isoforms of nitric oxide synthase and it is a newly discovered risk factor in the setting of diseases associated with endothelial dysfunction and adverse cardiovascular events. In the context of systemic inflammatory disorders there is increasing evidence that ADMA contributes to the vascular changes and to endothelial cell abnormalities, as several studies have revealed derangement of nitric oxide/ADMA pathway in different disease subsets. In this article we discuss the role of endothelial dysfunction in patients with rheumatic diseases, with a specific focus on the nitric oxide/ADMA system and we provide an overview on the literature pertaining to ADMA as a surrogate marker of subclinical vascular disease.
International Journal of Molecular Sciences 12/2012; 13(10):12315-35. DOI:10.3390/ijms131012315 · 2.86 Impact Factor
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