ADMA and arginine derivatives in relation to non-invasive vascular function in the general population

[Integrative assessment of the effectiveness and safety of outpatient use of Picamilon]

OBJECTIVE

To study the efficacy and safety of the use of the drug Picamilon with various therapy regimens in patients with stage I of chronic cerebral ischemia (CCI).

MATERIAL AND METHODS

Material and methods. An open randomized comparative clinical trial included 44 patients with stage CCI aged 46 to 67 years (average age 55.6±6.76 years). Patients were randomized into two groups, patients of group 1 (n=23) received Picamilon orally in tablets of 50 mg 3 times/day for 60 days; group 2 (n=21) received Picamilon first parenterally at 100 mg i/m for 10 days, then in tablets of 50 mg 3 times/day for 50 days. The total duration of therapy was 60 days. The study included 4 visits (before treatment, 10 days later, 60 days later, 1.5 months after completion of treatment). The dynamics of cognitive status were assessed according to the Montreal Cognitive Function Assessment Scale (MoCA), vegetative disorders on the A.M. Wayne scale, neurological disorders on the A.I. Fedin scale, and sleep quality on the Ya.I. Levin scale. The study of the state of cerebral blood flow (dopplerography of intracranial vessels) and endothelial function (assessment of the level of methylation.

RESULTS

During treatment, in the total sample of patients, there was a positive trend in the results of the MoCA scale, increasing in the delayed period (24.9/26.5/28.3 points, p=0.022 and p<0.001); improvement in sleep quality in 50% of patients by visit 3 and in 84% by visit 4, in the 2nd group the effect occurred in 28% of patients, in the 1st - in 11%, by the end of the study the effect was comparable (p=0.508). Improvement according to Fedin A.I. scale noted in 77% of patients, values decreased from 11.9±8.3 to 6±6.1 points (p<0.0001) and to 2.77±4.43 points by visit 4 (p<0.0001). Normalization of autonomic functions was observed in 29% of patients (p=0.024) without intergroup differences. Picamilon therapy showed high efficacy in terms of clinical outcomes (up to 89%), good tolerability (98% of patients) and a favorable safety profile (less than 8.6% of AEs). The use of Picamilon was accompanied by an increase in the linear velocity of blood flow, a decrease in the thickness of the intima-media complex and the resistance index; a decrease in elevated ADMA concentrations and ADMA/MMA and (ADMA+SDMA)/MMA ratios.

CONCLUSION

The use of Picamilon is effective in patients with stage I CCI, contributes to a significant regression of neurological deficits, cognitive impairment, improved sleep quality and autonomic function; improves vascular endothelial function, reduces the risk of atherosclerosis and cardiovascular complications in patients. The optimal duration of therapy with Picamilon in stage I of chronic cerebral ischemia is 2 months.

[Clinical efficacy and safety of Picamilon in patients with progressive chronic cerebral ischemia]

OBJECTIVE

To study the efficacy and safety of the drug Picamilon with various therapy regimens in patients with stage II chronic cerebral ischemia (CCI).

MATERIAL AND METHODS

An open cohort clinical study involved 50 patients diagnosed with stage II CCI aged 51 to 69 years (average age 62.2±8.98 years). Patients received Picamilon first parenterally 200 mg (100 mg/ml, 2 ml) intravenously for 10 days, then orally in 50 mg tablets 3 times a day for 60 days. The total duration of therapy in the group was 70 days. The study included 3 visits (before treatment, after completion of the course, 1.5 months after completion of treatment). The dynamics of cognitive status according to the Montreal Cognitive Assessment Scale, vegetative disorders according to the A.M. Vane scale, neurological disorders according to the A.I. Fedin scale, and sleep quality according to the Ya. I. Levin scale were compared. The state of cerebral blood flow and endothelium was studied before and after treatment: dopplerography of cranial vessels, assessment of the level of methylated forms of arginine (ADMA, MMA, SDMA) and their ratios. The registration of adverse events against the background of therapy and the tolerability of treatment by patients was also carried out.

RESULTS

Against the background of Picamilon treatment, a significant positive dynamics of the MoCA scale results was observed in the general sample of patients, increasing in the delayed period (20.9, 24.6 and 25.9, p<0.0001 and p=0.0006); sleep normalization was observed in 55% of patients by Visit 2 and in 81% of patients by Visit 3 (p<0.0001 and p=0.0025). Improvement of neurological functions is noted in 84% of patients, the score on the Fedin A.I. scale significantly decreases after treatment from 17.4±9.34 to 8.06±6.84 (p<0.0001) and to 5.31±5.71 in the delayed period (p=0.0002). Normalization of vegetative status was observed in 38% of patients with stage II CCI, and in 60% of cases there was a decrease in the severity of vegetative dystonia syndrome (p=0.0001). Picamilon therapy has high efficacy in assessing clinical outcomes (100%), good tolerability in 98% of patients and is characterized by a favorable safety profile (in 92% of patients). Picamilon significantly affects the parameters of cerebral hemodynamics: increases the linear velocity of blood flow, reduces the thickness of the intima-media complex and the resistance index. It affects markers of NO metabolism and endothelial function: significantly reduces elevated levels of ADMA and ADMA/MMA and (ADMA+SDMA)/MMA ratios.

CONCLUSION

The use of Picamilon is effective in patients with stage II CCI in the form of step therapy contributes to a significant regression of neurological deficit, cognitive impairment, improvement of sleep quality and autonomic function; improves vascular endothelial function, reduces the risk of cardiovascular complications. Picamilon is a pathogenetic therapy agent that prevents the progression of CCI.

COVID-19 and its effects on endothelium in HIV-positive patients in sub-Saharan Africa: Cardiometabolic risk, thrombosis and vascular function (ENDOCOVID STUDY)

BACKGROUND

COVID-19 has affected almost every country in the world, especially in terms of health system capacity and economic burden. People from sub-Saharan Africa (SSA) often face interaction between human immunodeficiency virus (HIV) infection and non-communicable diseases such as cardiovascular disease. Role of HIV infection and anti-retroviral treatment (ART) in altered cardiovascular risk is questionable and there is still need to further carry out research in this field. However, thus far it is unclear, what impact the COVID-19 co-infection in people living with HIV (PLHIV), with or without therapy will have. The ENDOCOVID project aims to investigate whether and how HIV-infection in COVID-19 patients modulates the time course of the disease, alters cardiovascular risk, and changes vascular endothelial function and coagulation parameters/ thrombosis risk.

METHODS

A total of 1026 patients will be included into this study. Cardiovascular research PLHIV with (n = 114 in each of the three recruiting centers) - or without - ART (n = 114 in each of the three recruiting centers) with COVID-19 and HIV-negative with COVID-19 (n = 114 in each of the three recruiting centers) will be carried out via clinical and biochemical measurements for cardiovascular risk factors and biomarkers of cardiovascular disease (CVD). Vascular and endothelial function will be measured by brachial artery flow-mediated dilatation (FMD), carotid intima-media thickness (IMT) assessments, and retinal blood vessel analyses, along with vascular endothelial biomarkers and cogualation markers. The correlation between HIV-infection in COVID-19 PLHIV with or without ART and its role in enhancement of cardiovascular risk and endothelial dysfunction will be assessed at admission, weekly, at discharge and, 4 weeks post-discharge (if possible).

IMPACT OF PROJECT

The ENDOCOVID project aims to evaluate in the long-term the cardiovascular risk and vascular endothelial function in PLHIV thus revealing an important transitional cardiovascular phenotype in COVID-19. The study was registered under clinicaltrials.gov (NCT04709302).

[Asymmetric dimethylarginine (ADMA) in retinal vein occlusion-Results from the Gutenberg RVO study]

BACKGROUND

Asymmetric dimethylarginine (ADMA) is considered an independent cardiovascular risk factor (cvRF) and thus represents a potential new biomarker for retinal vein occlusion (RVO).

METHODS

Overall, 92 patients with RVO and the same number of matched controls were included in the Gutenberg RVO study. All patients underwent a standardized examination for cvRF at the study center of the population-based Gutenberg health study (GHS) as well as ophthalmological examinations and intensive laboratory tests. This article presents a substudy of patients (≤65 years old) and the controls in whom ADMA was additionally determined by high performance liquid chromatography (HPLC) at baseline and 4-6 weeks later.

RESULTS

Out of 44 patients with RVO 22 had central retinal vein occlusion (CRVO), 15 had branch retinal vein occlusion (BRVO) and 7 had hemiretinal vein occlusion (hemi-RVO). The ADMA levels were 0.383 ± 0.094 µM (mean ± standard deviation) in RVO patients at baseline and 0.380 ± 0.093 µM (p = 0.514, initial vs. follow-up) after the follow-up period versus 0.360 ± 0.077 µM (p = 0.175, controls vs. RVO) in controls (n = 44). Arterial hypertension was the most prevalent risk factor in 22 (50%) of the patients and in 11 (25%) of the controls (odds ratio, OR 2.77, 95% confidence interval, CI 0.97-7.95; p = 0.058). The ADMA values above the 95th percentile (>0.530 µM) were detected in 4 patients with RVO (9.1%) but not in any of the controls (p = 0.041, RVO vs. controls).

CONCLUSION

Hypertension is the most important risk factor for RVO. Due to the high number of hypertensive patients in the cohort, the relevance of ADMA as an independent risk factor could neither be confirmed nor disproved.

Metabolic Pathways Fueling the Endothelial Cell Drive

Endothelial cell (EC) metabolism is important for health and disease. Metabolic pathways, such as glycolysis, fatty acid oxidation, and amino acid metabolism, determine vasculature formation. These metabolic pathways have different roles in securing the production of energy and biomass and the maintenance of redox homeostasis in vascular migratory tip cells, proliferating stalk cells, and quiescent phalanx cells, respectively. Emerging evidence demonstrates that perturbation of EC metabolism results in EC dysfunction and vascular pathologies. Here, we summarize recent insights into EC metabolic pathways and their deregulation in vascular diseases. We further discuss the therapeutic implications of targeting EC metabolism in various pathologies.

Increased symmetric dimethylarginine, but not asymmetric dimethylarginine, concentrations are associated with transient myocardial ischemia and predict outcome

Objective

Asymmetric and symmetric dimethylarginines (ADMA and SDMA) are endothelial dysfunction markers. ADMA inhibits synthesis of nitric oxide. We aimed to analyze both markers in patients with coronary artery disease (CAD) who were referred for stress/rest myocardial perfusion scintigraphy (MPS).

Methods

All patients underwent a 2-day dipyridamole (DP) stress/rest protocol. Thereafter, patients with transient myocardial perfusion abnormality were followed up and their coronary blood flow was quantitatively assessed. Venous blood was taken before and after DP stress to measure markers.

Results

Baseline ADMA and SDMA concentrations were significantly higher in patients with CAD compared with healthy subjects. Pre- and post-stress SDMA concentrations were significantly higher in patients with transient myocardial perfusion abnormality compared with those with negative MPS results. However, ADMA and L-arginine concentrations were not significantly different between the two groups. None of the markers were significantly different between patients with angiographically proven low coronary flow and those with normal coronary flow. Pre-stress SDMA concentrations were an independent predictor of cardiovascular mortality during a 8-year follow-up.

Conclusions

Elevated serum SDMA concentrations may be helpful for selecting high-risk patients with CAD if there is any doubt in interpreting MPS. SDMA concentrations may also predict cardiovascular outcome.

Arginine Derivatives in Cerebrovascular Diseases: Mechanisms and Clinical Implications

The amino acid L-arginine serves as substrate for the nitric oxide synthase which is crucial in vascular function and disease. Derivatives of arginine, such as asymmetric (ADMA) and symmetric dimethylarginine (SDMA), are regarded as markers of endothelial dysfunction and have been implicated in vascular disorders. While there is a variety of studies consolidating ADMA as biomarker of cerebrovascular risk, morbidity and mortality, SDMA is currently emerging as an interesting metabolite with distinct characteristics in ischemic stroke. In contrast to dimethylarginines, homoarginine is inversely associated with adverse events and mortality in cerebrovascular diseases and might constitute a modifiable protective risk factor. This review aims to provide an overview of the current evidence for the pathophysiological role of arginine derivatives in cerebrovascular ischemic diseases. We discuss the complex mechanisms of arginine metabolism in health and disease and its potential clinical implications in diverse aspects of ischemic stroke.

Sources of Vascular Nitric Oxide and Reactive Oxygen Species and Their Regulation

Nitric oxide (NO) is a small free radical with critical signaling roles in physiology and pathophysiology. The generation of sufficient NO levels to regulate the resistance of the blood vessels and hence the maintenance of adequate blood flow is critical to the healthy performance of the vasculature. A novel paradigm indicates that classical NO synthesis by dedicated NO synthases is supplemented by nitrite reduction pathways under hypoxia. At the same time, reactive oxygen species (ROS), which include superoxide and hydrogen peroxide, are produced in the vascular system for signaling purposes, as effectors of the immune response, or as byproducts of cellular metabolism. NO and ROS can be generated by distinct enzymes or by the same enzyme through alternate reduction and oxidation processes. The latter oxidoreductase systems include NO synthases, molybdopterin enzymes, and hemoglobins, which can form superoxide by reduction of molecular oxygen or NO by reduction of inorganic nitrite. Enzymatic uncoupling, changes in oxygen tension, and the concentration of coenzymes and reductants can modulate the NO/ROS production from these oxidoreductases and determine the redox balance in health and disease. The dysregulation of the mechanisms involved in the generation of NO and ROS is an important cause of cardiovascular disease and target for therapy. In this review we will present the biology of NO and ROS in the cardiovascular system, with special emphasis on their routes of formation and regulation, as well as the therapeutic challenges and opportunities for the management of NO and ROS in cardiovascular disease.

Homoarginine/ADMA ratio and homoarginine/SDMA ratio as independent predictors of cardiovascular mortality and cardiovascular events in lower extremity arterial disease

Endothelial dysfunction plays a key role in development of atherosclerosis and lower extremity arterial disease (LEAD). Homoarginine, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) are sensitive markers for endothelial dysfunction and independent risk factors for cardiovascular death. However, homoarginine may influence the proatherogenic effects of ADMA and SDMA suggesting homoarginine/ADMA ratio or homoarginine/SDMA ratio as further predictors for cardiovascular mortality. Therefore, we investigated the predictive value of homoarginine/ADMA ratio and homoarginine/SDMA ratio related to cardiovascular mortality and cardiovascular events in claudicant patients with LEAD. 151 patients with intermittent claudication were included in a prospective observational study (observation time 7.7 ± 2.5 years) with cardiovascular mortality as main outcome parameter and the occurrence of cardiovascular events as secondary outcome parameter. Homoarginine, ADMA and SDMA were measured by high-performance liquid chromatography at baseline. Low homoarginine/ADMA ratio and homoarginine/SDMA ratio were independently associated with higher cardiovascular mortality (HR 2.803 [95% CI 1.178–6.674], p = 0.020; HR 2.782 [95% CI 1.061–7.290], p = 0.037, respectively) and higher incidence of cardiovascular events (HR 1.938 [95% CI 1.015–3.700], p = 0.045; HR 2.397 [95% CI 1.243–4.623], p = 0.009, respectively). We observed that homoarginine/ADMA ratio and homoarginine/SDMA ratio are independent predictors for long-term cardiovascular mortality and events in claudicant patients with LEAD.

Impaired Endothelial Function in Hereditary Angioedema During the Symptom-Free Period

Introduction: The presence of coronary endothelial dysfunction was previously shown in Hereditary Angioedema (HAE) patients. The aim of our study was to evaluate the effect of HAE on systemic endothelial function and whether there was a relationship among endothelial function, asymmetric dimethylarginine (ADMA) -which is a strong inhibitor of nitric oxide synthesis-, and disease severity scores.

Methods: Twenty-four HAE patients (18 females, aged 47.9 ± 2 years) without factors known to interfere with endothelial function were studied and compared with 24 healthy peers age- and gender-matched. Endothelial function was assessed by means of non-invasive finger plethysmography (reactive hyperaemia index: RHI) and ADMA levels by high-performance liquid chromatography. HAE severity scores have been calculated according to published literature.

Results: In HAE patients RHI was lower (2.03 ± 0.46 vs. 2.82 ± 0.34, p < 0.0001) and ADMA higher (0.636 ± 7 vs. 585 ± 5 micromol/L, p < 0.01) than in controls. A statistically significant inverse correlation was revealed between RHI and patients' ADMA levels (r = −0.516, p = 0.009) as well as between RHI and patients' chronological age (r = −0.49, p = 0.015). A statistically significant correlation between RHI and ADMA was confirmed even when excluding the possible influence of cholesterol (r = −0.408, p = 0.048). No other significant correlations were found with the examined laboratory and clinical parameters (chronological age, age at disease onset, disease duration, severity scores, and gender).

Conclusion: The dysfunction previously shown in HAE patients at the coronary arteries seems to involve the peripheral vessels as well, without a correlation with disease severity.

Serum Concentrations of New Predictive Cardiovascular Disease Biomarkers in Mexican Women Exposed to Lead

The purpose of this study was to evaluate lead exposure and its relationship with serum levels of predictive CVD biomarkers [asymmetric dimethylarginine (ADMA), adipocyte fatty acid-binding protein (FABP4), adiponectin, and chemerin] in women living in San Luis Potosi, Mexico. A mean blood lead level (BLL) of 11.5 ± 9.00 μg/dL (mean ± standard deviation) was found after all blood samples were analyzed. Regarding serum predictive CVD biomarkers, mean serum level of 0.68 ± 0.38 μmol/L, 20.5 ± 16.5 ng/mL, 12.5 ± 3.30 μg/mL, and 255 ± 130 ng/mL were found for ADMA, FABP4, adiponectin, and chemerin, respectively. Simple significant associations (Pearson´s correlations) between BLL and ADMA (r = 0.17; p = 0.04) and FABP4 (r = 0.23; p = 0.03) were found. Furthermore, a multivariate linear regression model showed that BLL was a significant predictor of serum ADMA (β = 0.06; p = 0.001) and FABP4 (β = 1.75; p = 0.0004) concentrations after adjusting by confounders. For serum chemerin and adiponectin levels, no associations were found with BLL. In conclusion, high serum ADMA and FABP4 (predictive CVD biomarkers) levels were found in women exposed to lead. Consequently, this research can be used as a point of departure for the prevention of CVD events in populations living in sites environmentally impacted with lead.

Endothelial Cell Metabolism

Endothelial cells (ECs) are more than inert blood vessel lining material. Instead, they are active players in the formation of new blood vessels (angiogenesis) both in health and (life-threatening) diseases. Recently, a new concept arose by which EC metabolism drives angiogenesis in parallel to well-established angiogenic growth factors (e.g., vascular endothelial growth factor). 6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3-driven glycolysis generates energy to sustain competitive behavior of the ECs at the tip of a growing vessel sprout, whereas carnitine palmitoyltransferase 1a-controlled fatty acid oxidation regulates nucleotide synthesis and proliferation of ECs in the stalk of the sprout. To maintain vascular homeostasis, ECs rely on an intricate metabolic wiring characterized by intracellular compartmentalization, use metabolites for epigenetic regulation of EC subtype differentiation, crosstalk through metabolite release with other cell types, and exhibit EC subtype-specific metabolic traits. Importantly, maladaptation of EC metabolism contributes to vascular disorders, through EC dysfunction or excess angiogenesis, and presents new opportunities for anti-angiogenic strategies. Here we provide a comprehensive overview of established as well as newly uncovered aspects of EC metabolism.

Endothelial cell metabolism: A novel player in atherosclerosis? Basic principles and therapeutic opportunities

Atherosclerosis is a leading cause of morbidity and mortality in Western society. Despite improved insight into disease pathogenesis and therapeutic options, additional treatment strategies are required. Emerging evidence highlights the relevance of endothelial cell (EC) metabolism for angiogenesis, and indicates that EC metabolism is perturbed when ECs become dysfunctional to promote atherogenesis. In this review, we overview the latest insights on EC metabolism and discuss current knowledge on how atherosclerosis deregulates EC metabolism, and how maladaptation of deregulated EC metabolism can contribute to atherosclerosis progression. We will also highlight possible therapeutic avenues, based on targeting EC metabolism.