Effect of iloprost on plasma asymmetric dimethylarginine and plasma and platelet serotonin in patients with peripheral arterial occlusive disease

Subclinical atherosclerosis in systemic sclerosis: Different risk profiles among patients according to clinical manifestations

INTRODUCTION

Like other autoimmune diseases, systemic sclerosis (SSc) has been described to be associated with accelerated atherosclerosis (ATS). Before clinical manifestations of cardiovascular disease (CVD) occur, subclinical ATS can be investigated in different ways.

AIM

To evaluate the presence of subclinical ATS in a group of patients with SSc, and to identify different risk profiles among patients.

METHODS

Subclinical ATS was reviewed in 43 SSc patients and 27 healthy controls, using 2 methods: carotid ultrasound and flow mediated dilation (FMD) of the brachial artery.

RESULTS

Plaques were statistically more frequent in SSc patients than in controls (65% vs 30%, P = .006); intima-media thickness of common carotid artery (CCA-IMT) resulted in statistically higher (median value 0.8 mm vs 0.55 mm; P < .0001) while FMD was significantly lower (median value 9% vs 14%; P = .0086) in patients compared to healthy controls. Among the SSc patients, thickening of CCA-IMT was significantly associated with the presence of diastolic dysfunction of left ventricle (absence of diastolic dysfunction: odds ratio [OR] 0.2, 95% CI 0.04-0.92, P = .038) and with a higher Framingham score (OR 1.3, 95% CI 1.03-1.6], P = .024). The diffuse cutaneous form was slightly protective against pathological FMD (OR 0.12, 95% CI 0.022-0.71, P = .019).

CONCLUSIONS

This study confirms the involvement of macrocirculation in SSc patients, detecting the presence of subclinical ATS markers more frequently in patients compared to healthy controls. Framingham score, diastolic dysfunction of left ventricle and limited cutaneous form of the disease appeared to be associated with a higher risk of developing ATS.

Prostanoids for Critical Limb Ischemia: A Clinical Review and Consideration of Current Guideline Recommendations

For many years, the only pharmacological option for patients with critical limb ischemia (CLI) unsuitable for revascularization has been prostanoids; however, some recent guidelines have become very restrictive regarding their use. We review the available evidence on the use of prostanoids and analyze the guideline positions as well as the possible reasons for changes over time. In most placebo-controlled trials and meta-analyses, prostanoids showed a significant effect in improving rest pain, promoting ulcer healing and reducing major amputations. Results for iloprost were especially consistent. Different prostanoid drugs have different evidence of efficacy, thus using a generic term "prostanoids" is misleading. Unfortunately, the available evidence is often of low quality and probably not sufficient to support an extensive use of prostanoids in all patients, and further high-quality randomized trials are needed. Consequently, some recent guidelines do not recommend treatment with prostanoids in this setting. However, in our opinion, pending definitive evidence, patients with CLI who have a viable limb in whom revascularization is unfeasible or has a poor chance of success, without alternative to amputation, may benefit from treatment with iloprost, balancing harms and benefits in each case.

Plasma L-arginine levels distinguish pulmonary arterial hypertension from left ventricular systolic dysfunction

Pulmonary arterial hypertension (PAH) is a life-threatening condition, characterized by an imbalance of vasoactive substances and remodeling of pulmonary vasculature. Nitric oxide, formed from L-arginine, is essential for homeostasis and smooth muscle cell relaxation in PAH. Our aim was to compare plasma concentrations of L-arginine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) in PAH compared to left ventricular systolic dysfunction (LVSD) and healthy subjects. This was an observational, multicenter study comparing 21 patients with PAH to 14 patients with LVSD and 27 healthy subjects. Physical examinations were obtained and blood samples were collected. Plasma levels of ADMA, SDMA, L-arginine, L-ornithine, and L-citrulline were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Plasma levels of ADMA and SDMA were higher, whereas L-arginine and L-arginine/ADMA ratio were lower in PAH patients compared to healthy subjects (p < 0.001). Patients with PAH also had lower levels of L-arginine than patients with LVSD (p < 0.05). L-Arginine correlated to 6 min walking distance (6MWD) (r _s = 0.58, p = 0.006) and L-arginine/ADMA correlated to WHO functional class (r _s = -0.46, p = 0.043) in PAH. In conclusion, L-arginine levels were significantly lower in treatment naïve PAH patients compared to patients with LVSD. Furthermore, L-arginine correlated with 6MWD in PAH. L-arginine may provide useful information in differentiating PAH from LVSD.

Altered expression of eNOS, prostacyclin synthase, prostaglandin G/H synthase, and thromboxane synthase in porcine aortic endothelial cells after exposure to human serum-relevance to xenotransplantation

Under normal conditions, the activity of platelets is stringently and precisely balanced between activation and quiescent state. This guarantees rapid hemostasis and avoids uncontrolled thrombosis. However, excessive platelet activation and resulting thrombotic microangiopathy are frequently observed in pig-to-primate xenotransplantation models. Endothelium-derived inhibitory mechanisms play an important role in regulation of platelet activation. These mainly include nitric oxide (NO), prostacyclin PGI₂ , and adenosine, which are synthesized by endothelial NO synthases (eNOS), prostacyclin synthase, and CD39/CD73, respectively. We investigated whether endothelium-derived regulatory mechanisms are affected in porcine aortic endothelial cells (PAECs) after exposure to human serum. In the present study, exposure of PAECs or porcine iliac arteries to human serum suppressed gene expression of eNOS and prostacyclin synthase, while induced gene expression of prostaglandin G/H synthase and thromboxane synthase. Simultaneously, exposure to human serum reduced NO and PGI₂ production in PAEC culture supernatants. Thus, human serum altered the balance of endothelium-derived inhibitory mechanisms in PAECs, which may indicate a regulatory mechanism of excessive platelet activation in pig-to-primate xenotransplantation.

Investigation of Asymmetric and Symmetric Dimethylarginine Levels after Iloprost Treatment in Patients with Buerger's Disease

OBJECTIVE

The aim of this study was to compare the levels of acetyl-dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and the l-arginine/ADMA ratio before and after iloprost treatment in patients with Buerger's disease.

METHODS

Between January 2011 and December 2015, data from 44 patients (36 males, 8 females, mean age 48.7 ± 18.1 years) with the diagnosis of Fontaine Stage III-IV Buerger's disease were included. Iloprost infusion was administered intravenously through the forearm veins for 7 days at a dose of 0.5-1.5 ng/kg/min over 16 h. Blood samples were collected before and after treatment for measurement of ADMA, SDMA, and l-arginine. ADMA, SDMA, l-arginine levels were measured using high performance liquid chromatography (HPLC).

RESULTS

After iloprost treatment, ADMA and SDMA levels significantly decreased (p = .001). The increase in the l-arginine levels was not significant (p = .16). However, the l-arginine/ADMA ratio increased significantly (p = .001).

CONCLUSION

Iloprost treatment decreases ADMA and SDMA, which are associated with endothelial dysfunctions in patients with Buerger's disease. Of note, the still higher than normal range of SDMA levels after iloprost treatment suggests that treatment should continue until SDMA levels are within the normal range in this patient population.

The role of asymmetric and symmetric dimethylarginine in acute deep vein thrombosis

BACKGROUND

In this study, we aimed to determine the importance of asymmetric dimethylarginine (ADMA), symmetric dimethyl arginine (SDMA), and l-arginine levels which are influenced by the endothelial dysfunction in acute deep vein thrombosis (DVT), and compare their pretreatment and post-treatment levels.

METHODS

A total of 34 cases (19 men and 15 women, age range 42 ± 14 years) diagnosed with acute DVT and 34 control subjects (22 men and 12 women, age range 45 ± 11 years) without any vascular disorders were included in the study. The patients were administered low-molecular-weight heparin subcutaneously. Blood samples were obtained to measure ADMA, SDMA, and arginine levels before treatment and during the treatment (on 10th day). ADMA, SDMA, and l-arginine levels were measured using high performance liquid chromatography method.

RESULTS

The ADMA and SDMA levels were significantly higher in acute DVT patients when compared with the controls (P = 0.001). Post-treatment decrease of ADMA and SDMA levels when compared with the pretreatment levels were found as statistically significant (P = 0.001). Increase in l-arginine levels were not found significant when compared with the control group (P = 0.12) or post-treatment levels (P = 0.16).

CONCLUSIONS

We concluded that ADMA and SDMA levels can be used as parameters in clinical follow-up for determining the efficacy of treatment in acute DVT patients, and further studies are needed to further clarify the subject.

Intravenous iloprost for treatment of critical limb ischemia in patients unsuitable for revascularization

Introduction

Whether medical therapy alone may reduce the amputation rates in patients with chronic limb ischemia and who are unsuitable for revascularization is a controversial topic. In this study, we aimed to investigate the effects of 1 week infusion of iloprost in the treatment of patients with chronic limb ischemia.

Materials and methods

Twenty-seven consecutive patients were included in the study. There were 23 men (85.2%) and 4 women (14.8%) with a mean age of 68.93 ± 14.84 years. Patients were considered eligible if they were unsuitable for surgical and endovascular revascularization. Follow-up was made on 10th day and 6th month and included ankle brachial index and clinical assessment.

Results

Minor side effects occurred in four patients (16.0%), but the treatment was continued. In-hospital mortality occurred in one patient (4.0%). Another two patients died and four patients received amputation until follow-up (overall mortality 11.1%). There was significant increase in mean ankle-brachial index values between 1st day and 10th day ( p < 0.001), between 1st day and 6th month ( p < 0.001), and between 10th day and 6th month ( p < 0.001).

Conclusion

One-week treatment with iloprost may provide both long lasting symptomatic benefit and may improve hemodynamic parameters, which were shown to predict future amputation.

Asymmetric dimethylarginine as a surrogate marker of endothelial dysfunction and cardiovascular risk in patients with systemic rheumatic diseases

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.

Molecular mechanisms regulating the vascular prostacyclin pathways and their adaptation during pregnancy and in the newborn

Prostacyclin (PGI(2)) is a member of the prostanoid group of eicosanoids that regulate homeostasis, hemostasis, smooth muscle function and inflammation. Prostanoids are derived from arachidonic acid by the sequential actions of phospholipase A(2), cyclooxygenase (COX), and specific prostaglandin (PG) synthases. There are two major COX enzymes, COX1 and COX2, that differ in structure, tissue distribution, subcellular localization, and function. COX1 is largely constitutively expressed, whereas COX2 is induced at sites of inflammation and vascular injury. PGI(2) is produced by endothelial cells and influences many cardiovascular processes. PGI(2) acts mainly on the prostacyclin (IP) receptor, but because of receptor homology, PGI(2) analogs such as iloprost may act on other prostanoid receptors with variable affinities. PGI(2)/IP interaction stimulates G protein-coupled increase in cAMP and protein kinase A, resulting in decreased [Ca(2+)](i), and could also cause inhibition of Rho kinase, leading to vascular smooth muscle relaxation. In addition, PGI(2) intracrine signaling may target nuclear peroxisome proliferator-activated receptors and regulate gene transcription. PGI(2) counteracts the vasoconstrictor and platelet aggregation effects of thromboxane A(2) (TXA(2)), and both prostanoids create an important balance in cardiovascular homeostasis. The PGI(2)/TXA(2) balance is particularly critical in the regulation of maternal and fetal vascular function during pregnancy and in the newborn. A decrease in PGI(2)/TXA(2) ratio in the maternal, fetal, and neonatal circulation may contribute to preeclampsia, intrauterine growth restriction, and persistent pulmonary hypertension of the newborn (PPHN), respectively. On the other hand, increased PGI(2) activity may contribute to patent ductus arteriosus (PDA) and intraventricular hemorrhage in premature newborns. These observations have raised interest in the use of COX inhibitors and PGI(2) analogs in the management of pregnancy-associated and neonatal vascular disorders. The use of aspirin to decrease TXA(2) synthesis has shown little benefit in preeclampsia, whereas indomethacin and ibuprofen are used effectively to close PDA in the premature newborn. PGI(2) analogs have been used effectively in primary pulmonary hypertension in adults and have shown promise in PPHN. Careful examination of PGI(2) metabolism and the complex interplay with other prostanoids will help design specific modulators of the PGI(2)-dependent pathways for the management of pregnancy-related and neonatal vascular disorders.

Serotonin levels in platelet-poor plasma and whole blood in people with type 2 diabetes with chronic kidney disease

AIMS

Patients with diabetes mellitus (DM) are prone to atherosclerosis. Atherosclerosis activates platelets; activated platelets release serotonin, and therefore, evaluation of serotonin levels in blood could be a valuable biomarker for future risk of cardiovascular events.

METHODS

Plasma serotonin levels obtained from patients with DM complicated with chronic kidney disease were measured using HPLC and were compared to serotonin levels of healthy control subjects. Patients with DM were classified into 2 subgroups of mildly (group 1) and moderately/severely (group 2) impaired renal function.

RESULTS

Serotonin concentration in platelet-poor plasma for group 1 was significantly higher than that of healthy control subjects (p < 0.01), and was significantly higher than that of patients from group 2 (p < 0.05). The concentration of serotonin in whole blood for group 2 patients was significantly lower than that measured from healthy control subjects (p < 0.01). The ratio of the plasma to whole blood level was significantly elevated in both groups 1 and 2 compared with healthy controls (p < 0.01).

CONCLUSIONS

Our results indicate that platelets are activated to release serotonin into plasma in diabetic patients with mildly impaired renal function. When renal damage is advanced, platelets are over-activated to release serotonin.

Asymmetric dimethylarginine correlates with measures of disease severity, major adverse cardiovascular events and all-cause mortality in patients with peripheral arterial disease

Peripheral arterial disease (PAD) is associated with major cardiovascular morbidity and mortality. Abnormalities in nitric oxide metabolism due to excess of the NO synthase inhibitor asymmetric dimethylarginine (ADMA) may be pathogenic in PAD. We explored the association between ADMA levels and markers of atherosclerosis, function, and prognosis. A total of 133 patients with symptomatic PAD were enrolled. Ankle-brachial index (ABI), walking time, vascular function measures (arterial compliance and flow-mediated vasodilatation) and plasma ADMA level were assessed for each patient at baseline. ADMA correlated inversely with ABI (r = -0.238, p = 0.003) and walking time (r = -0.255, p = 0.001), independent of other vascular risk factors. We followed up 125 (94%) of our 133 initial subjects with baseline measurements (mean 35 months). Subjects with ADMA levels in the highest quartile (> 0.84 mumol/l) showed a significantly greater occurrence of a major adverse cardiovascular event (MACE) compared to those with ADMA levels in the lower three quartiles (p = 0.001). Cox proportional-hazards regression analysis revealed that ADMA was a significant predictor of MACE, independent of other risk factors including age, sex, blood pressure, smoking history, diabetes and ABI (hazard ratio = 5.1, p < 0.001). Measures of vascular function, such as compliance, flow-mediated vasodilatation (FMVD) and blood pressure, as well as markers of PAD severity, including ABI and walking time, were not predictive. In conclusion, circulating levels of ADMA correlate independently with measures of disease severity and major adverse cardiovascular events. Agents that target this pathway may be useful for this patient population. Clinical Trial Registration - URL: http:// www.clinicaltrials.gov. Unique identifier: NCT00284076.