Associations of plasma endothelin concentration with carotid atherosclerosis and asymptomatic cerebrovascular lesions in patients with essential hypertension

Impaired dynamic cerebral autoregulation is associated with the severity of neuroimaging features of cerebral small vessel disease

Aims

Cerebral small vessel disease (CSVD) is characterized by functional and structural changes in small vessels. We aimed to elucidate the relationship between dynamic cerebral autoregulation (dCA) and neuroimaging characteristics of CSVD.

Methods

A case‐control study was performed. Cerebral blood flow velocity (CBFV) of bilateral middle cerebral arteries and spontaneous arterial blood pressure were simultaneously recorded. Transfer function analysis was used to calculate dCA parameters (phase, gain, and the rate of recovery of CBFV [RoRc]). Neuroimaging characteristics of CSVD patients were evaluated, including lacunes, white matter hyperintensities (WMH), cerebral microbleeds (CMBs), perivascular spaces (PVS), and the total CSVD burden.

Results

Overall, 113 patients and 83 controls were enrolled. Compared with the control group, the phase at low frequency and the RoRc in CSVD patients were lower, and the gain at very low and low frequencies were higher, indicating bilaterally impaired dCA. Total CSVD burden, WMH (total, periventricular and deep), severe PVS, and lobar CMBs were independently correlated with the phase at low frequency.

Conclusions

Our findings suggested that dCA was compromised in CSVD patients, and some specific neuroimaging characteristics (the total CSVD burden, WMH, severe PVS and lobar CMBs) might indicate more severe dCA impairment in CSVD patients.

IL-6 Plasma Levels Correlate With Cerebral Perfusion Deficits and Infarct Sizes in Stroke Patients Without Associated Infections

Introduction: We aimed to investigate several blood-based biomarkers related to inflammation, immunity, and stress response in a cohort of patients without stroke-associated infections regarding their predictive abilities for functional outcome and explore whether they correlate with MRI markers, such as infarct size or location. Methods: We combined the clinical and radiological data of patients participating in two observational acute stroke cohorts: the PREDICT and 1000Plus studies. The following blood-based biomarkers were measured in these patients: monocytic HLA-DR, IL-6, IL-8, IL-10, LBP, MRproANP, MRproADM, CTproET, Copeptin, and PCT. Multiparametric stroke MRI was performed including T2^*, DWI, FLAIR, TOF-MRA, and perfusion imaging. Standard descriptive sum statistics were used to describe the sample. Associations were analyzed using Fischer's exact test, independent samples t-test and Spearmans correlation, where appropriate. Results: Demographics and stroke characteristics were as follows: 94 patients without infections, mean age 68 years (SD 10.5), 32.2% of subjects were female, median NIHSS score at admission 3 (IQR 2-5), median mRS 3 months after stroke 1 (IQR 0-2), mean volume of DWI lesion at admission 5.7 ml (SD 12.8), mean FLAIR final infarct volume 10 ml (SD 14.9), cortical affection in 61% of infarctions. Acute DWI lesion volume on admission MRI was moderately correlated to admission/maximum IL-6 as well as maximum LBP. Extent of perfusion deficit and mismatch were moderately correlated to admission/maximum IL-6 levels. Final lesion volume on FLAIR was moderately correlated to admission IL-6 levels. Conclusion: We found IL-6 to be associated with several parameters from acute stroke MRI (acute DWI lesion, perfusion deficit, final infarct size, and affection of cortex) in a cohort of patients not influenced by infections. Clinical Trial Registration: www.ClinicalTrials.gov, identifiers NCT01079728 and NCT00715533.

Associations of genetic variants of endothelin with cardiovascular complications in patients with renal failure

BACKGROUND

Cardiovascular (CV) complications are the main cause of death in end-stage renal disease (ESRD) patients. The high CV risks are attributable to the additive effects of multiple factors. Endothelin (EDN) is a potent vasoconstrictor and plays a role in regulating vascular homeostasis. However, whether variants of the EDN gene are associated with risks of CV events is not known. We conducted a study to investigate associations of variants of the EDN gene with CV events in ESRD patients.

METHODS

A cohort of 190 ESRD patients was recruited, and 19 tagged single-nucleotide polymorphisms within the EDN gene family were selected for genotyping through a TaqMan assay. Data on clinical characteristics and hospitalizations for CV events were collected. Associations of genetic variants of the EDN gene with CV events were analyzed.

RESULTS

In this cohort, 62% (n = 118) of patients were hospitalized for a CV event. The EDN1 rs4714384 (CC/TC vs. TT) polymorphism was associated with an increased risk of a CV event after multiple testing (p < 0.001). Further functional exploration showed that it was a quantitative trait locus which may significantly alter gene expression in the tibial artery.

CONCLUSIONS

EDN1 rs4714384 is very likely an important biomarker of CV events in ESRD patients.

Endothelin-1 Gene Polymorphism and Its Level Predict the Risk of Venous Thromboembolism in Male Indian Population

Objectives:

Genes related to endothelial function are responsible for the regulation of vascular functions.

Aim:

The aim of this study is to investigate whether endothelial gene-associated polymorphism and their plasma levels can be used to predict the risk for venous thromboembolism (VTE).

Methods:

We studied 133 patients with VTE and 164 healthy controls. Endothelin (EDN) G8002A, EDN T1370G, EDN 3A/4A, eNOSG894T, angiotensin-converting enzyme I/D, vascular endothelial growth factor C936T, and endothelial cell protein C receptor A6936G polymorphism was genotyped by restriction fragment length polymorphism. Plasma levels of endothelin 1 (EDN1), endothelial nitric oxide synthase, and angiotensin-converting enzyme were measured by enzyme-linked immunoassay kit.

Results:

The genotype and allele frequency between control and patients with VTE were significantly altered only for EDN T1370G polymorphism. The plasma EDN1 concentration was relatively higher in patients with VTE ( P = .0017) compared to healthy controls and showed an association with the EDN1 gene polymorphism in male Indian population. Logistic regression model analysis for EDN T1370G indicated a significant association between EDN G allele and occurrence of VTE.

Conclusion:

The EDN1 gene polymorphism may play a significant role in predicting individual’s susceptibility toward VTE and its clinical progression.

Genetic Polymorphisms in Endothelin-1 as Predictors for Long-Term Survival and the Cardiac Index in Patients Undergoing On-Pump Cardiac Surgery

Genetic variants within the endothelin-1 gene (EDN1) have been associated with several cardiovascular diseases and may act as genetic prognostic markers. Here, we explored the overall relevance of EDN1 polymorphisms for long-term survival in patients undergoing on-pump cardiac surgery. A prospectively collected cohort of 455 Caucasian patients who underwent cardiac surgery with cardiopulmonary bypass was followed up for 5 years. The obtained genotypes and inferred haplotypes were analyzed for their associations with the five-year mortality rate (primary endpoint). The EDN1 T-1370G and K198N genotype distributions did not deviate from Hardy–Weinberg equilibrium and the major allele frequencies were 83% and 77%, respectively. The cardiovascular risk factors were equally distributed in terms of the different genotypes and haplotypes associated with the two polymorphisms. The five-year mortality rate did not differ among the different EDN1 T-1370G and K198N genotypes and haplotypes. Haplotype analysis revealed that carriers of the G-T (compound EDN1 T-1370G G/K198N T) haplotype had a higher cardiac index than did non-carriers (p = 0.0008); however, this difference did not reach significance after adjusting for multiple testing. The results indicate that common variations in EDN1 do not act as prognostic markers for long-term survival in patients undergoing on-pump cardiac surgery.

Impact of endothelin-1 Lys198Asn polymorphism on coronary artery disease and endorgan damage in hypertensives

OBJECTIVE

Endothelin is the most potent endogenous vasoconstrictor and is involved in several vascular disorders such as arterial hypertension. Its intense interaction with other vasoactive hormone systems revealed the consideration about the endothelin gene as an interesting candidate for influencing the development of essential hypertension and hypertensive endorgan damage. The purpose of this study was to investigate the role of endothelin-1 Lys198Asn polymorphism in patients with severe arterial hypertension as well as associated endorgan damages.

METHODS

In 400 hypertensive patients and 150 normotensive controls we examined the endothelin-1 Lys198Asn polymorphism by DNA sequencing and patients were divided according to their genotype (GG, GT, and TT). Moreover, the frequency of endothelin-1 Lys198Asn polymorphism was investigated with respect to the prevalence of several actual or historical endorgan damages (renal disorder, coronary artery disease, vascular events, vascular damage, and congestive heart failure) in hypertensive patients.

RESULTS

Genotype distribution for endothelin-1 Lys198Asn polymorphism was 57.3% (GG), 41.3% (GT), and 1.43% (TT) in normotensive individuals; and in hypertensive individuals was 54.75% (GG), 43% (GT) and 2.25% (TT). Genotype distribution was unaffected in patients with severe hypertension, renal disorder, vascular events, vascular damage, and congestive heart failure. We, however, found a significant difference in hypertensive individuals with coronary artery disease and TT genotype (P=0.004).

CONCLUSION

Homozygous TT carrier contributes to a higher prevalence of coronary artery disease, especially for three-vessel disease in hypertensive individuals. Thus, the polymorphism at position 198 could serve as a possibility to differentiate high-risk subgroups in the heterogeneous population of hypertensive patients.

Endothelin

In humans, the endothelins (ETs) comprise a family of three 21-amino-acid peptides, ET-1, ET-2 and ET-3. ET-1 is synthesised from a biologically inactive precursor, Big ET-1, by an unusual hydrolysis of the Trp21 -Val22 bond by the endothelin converting enzyme (ECE-1). In humans, there are four isoforms (ECE-1a-d) derived from a single gene by the action of alternative promoters. Structurally, they differ only in the amino acid sequence of the extreme N-terminus. A second enzyme, ECE-2, also exists as four isoforms and differs from ECE-1 in requiring an acidic pH for optimal activity. Human chymase can also cleave Big ET-1 to ET-1, which is cleaved, in turn, to the mature peptide as an alternative pathway. ET-1 is the principal isoform in the human cardiovascular system and remains one of the most potent constrictors of human vessels discovered. ET-1 is unusual in being released from a dual secretory pathway. The peptide is continuously released from vascular endothelial cells by the constitutive pathway, producing intense constriction of the underlying smooth muscle and contributing to the maintenance of endogenous vascular tone. ET-1 is also released from endothelial cell-specific storage granules (Weibel-Palade bodies) in response to external stimuli. ETs mediate their action by activating two G protein-coupled receptor sub-types, ETA and ET(B). Two therapeutic strategies have emerged to oppose the actions of ET-1, namely inhibition of the synthetic enzyme by combined ECE/neutral endopeptidase inhibitors such as SLV306, and receptor antagonists such as bosentan. The ET system is up-regulated in atherosclerosis, and ET antagonists may be of benefit in reducing blood pressure in essential hypertension. Bosentan, the first ET antagonist approved for clinical use, represents a significant new therapeutic strategy in the treatment of pulmonary arterial hypertension (PAH).

Both Nitric Oxide and Endothelin-1 Influence Cerebral Blood Flow Velocity at Rest and after Hyper- and Hypocapnic Stimuli in Hypertensive and Healthy Adolescents

BACKGROUND AND PURPOSE

Nitric oxide (NO)/endothelin imbalance may play a role in the regulation of cerebral blood flow. The aim of the present study was to assess whether these endothelial factors influence middle cerebral artery blood flow velocities (MCAV) and cerebrovascular reactivity (CVR) in healthy and hypertensive adolescents.

SUBJECTS AND METHODS

106 adolescents (61 hypertensive and 45 normotensive) underwent transcranial Doppler measurements of the middle cerebral artery at rest and after 30 s of breath-holding (BH) and 60 s of hyperventilation (HV). Additionally, NO and endothelin-1 (ET-1) concentrations of the serum were assessed. The correlation between NO and ET-1 levels as well as MCAV and CVR values was analyzed.

RESULTS

Resting MCAVs were higher among hypertensive teenagers (76.5 +/- 24 vs. 62.8 +/- 15.6 cm/s, respectively, p < 0.001). CVR values did not differ between hypertensive and healthy adolescents after the BH and HV procedure. A significant negative correlation was found between absolute MCAV values and NO concentrations. ET-1 was positively related to MCAV.

CONCLUSIONS

Cerebral blood flow velocities, but not CVR values, are associated with serum NO and ET-1 concentrations in adolescents.

Target-organ damage in adolescent hypertension. Analysis of potential influencing factors, especially nitric oxide and endothelin-1

BACKGROUND AND PURPOSE

To assess the role of the nitric oxide-endothelin imbalance in the development of target-organ damages (carotid intima-media thickness and left ventricular mass index) in adolescent hypertension.

METHODS

125 adolescents--67 hypertensive and 58 normotensive--underwent routine anthropology (height, weight) and blood pressure measurements, and laboratory (glucose, cholesterol and triglyceride levels) testing as well as sampling blood for determination of the plasma concentrations of nitric oxide (NOx) and endothelin-1 (ET-1), followed by measurement of the carotid intima-media thickness (IMT) and left ventricular mass index (LVMI).

RESULTS

Plasma concentration of NOx was significantly lower (27.7+/-13.7 vs. 35.8+/-7.0 micromol/l, respectively, p<0.001) and ET-1 was higher (3.11+/-3.9 vs. 1.09+/-1.07 fmol/ml, respectively, p<0.001) in hypertensive adolescents than that of controls. NOx negatively, endothelin positively correlated with blood pressure values, especially with systolic BP. An inverse relationship has been found between NOx and ET-1 concentrations (r=-0.29, p<0.003). In this adolescent population body weight, systolic blood pressure and plasma ET-1 were the most important factors influencing IMT, whereas LVMI correlated with height and weight and systolic BP of the teenagers.

CONCLUSIONS

NO/endothelin imbalance seems to play a role in the development of hypertension and target-organ damages in adolescence. Further studies are encouraged in order to clarify the pathophysiological role of NO/endothelin imbalance in adolescent hypertension.

A functional biological marker is needed for diagnosing magnesium deficiency

Functional biological markers or biomarkers are now available for many nutrients which are used as nutritional status markers. Most sources of these biomarkers are products or precursors of enzymatic processes that can be measured in serum and plasma. At this time measurements of total or ionized magnesium (Mg) in serum, plasma, cellular components, urine or Mg retention from a load test are performed, but they may not always reflect Mg nutritional status. Biomarkers for Mg are needed which would reflect changes in biochemical processes where Mg is involved. Biomarkers for Mg need to be identified and evaluated in both animals and humans, with a determination of possible factors that may affect the reaction and biomarker concentrations. Some possible biomarkers for Mg include the following: Na/K ATPase, thromboxane B2, C-reactive protein, and endothelin-1. Other possible biomarkers for Mg need to be identified.

Evaluation of the Lys198Asn and -134delA Genetic Polymorphisms of the Endothelin-1 Gene

Endothelin-1 (ET-1) is a potent vasoconstrictor and shows various pharmacological responses. Two single nucleotide polymorphisms in the ET-1 gene (EDN1) have been reported to be associated with blood pressure (BP). One is the Lys198Asn polymorphism, which showed a positive association with BP in overweight people. Another is the 3A/4A polymorphism (-134delA) located in the 5'-untranslated region. In this study, we investigated the expression of the Lys198Asn polymorphism in ET-1 in vitro, as well as the association between either of the two polymorphisms and the plasma ET-1 level. We expressed both the major (Lys-type) and minor type (Asn-type) preproET-1 in three different cell lines, and measured the levels of ET-1 and big ET-1 in the culture supernatant. There was no significant difference in the levels of ET-1 or big ET-1 between the Asn-type and Lys-type transfectant. In the association study, the plasma levels of ET-1 in 54 hypertensive patients having an amino acid substitution from Lys to Asn at position 198 were not different from those of hypertensives without the substitution. However, we found a significant difference in ET-1 levels between individuals with the 3A/3A and 3A/4A genotypes. Our transient expression study indicates that the Lys198Asn polymorphism may not directly affect ET-1 and big ET-1 production. Another variant in the EDN1 gene in linkage disequilibrium with the Lys198Asn polymorphism may be responsible for the association with BP, or the interaction between the EDN1 Lys198Asn polymorphism and other factors such as obesity may be involved in the mechanisms elevating BP in vivo.

Smoking is Associated with Silent Cerebrovascular Disease in a High-Risk Japanese Community-Dwelling Population

We aimed to investigate the relationships between smoking and silent cerebrovascular damage. We performed brain MRI to evaluate silent cerebral infarct (SCI) and periventricular hyperintensity (PVH), and carotid-ultrasonography to investigate carotid atherosclerotic plaque in 170 high-risk community-dwelling subjects (mean age: 67.2 years; men: 28.7%) who met more than 3 of the following 9 criteria: 1) high blood pressure (BP); 2) hypercholesterolemia; 3) left ventricular hypertrophy; 4) high hemoglobin A1c; 5) proteinuria; 6) high waist-to-hip ratio; 7) smoking > or =30 cigarettes/day; 8) heavy alcohol intake; 9) family history of stroke. The subjects with SCI (SCI group) were older (70 years vs. 66 years, p=0.004) and had higher systolic BP (SBP) (160 vs. 148 mmHg, p <0.001) and higher carotid plaque score (2.3 vs. 1.5/person, p <0.05) than those without SCI. Among the variables, smoking status (r =0.34, p <0.001), SBP (r =0.28, p <0.001), male gender (r =0.29, p <0.001), left ventricular mass index (r =0.25, p =0.001), and serum creatinine (r =0.20, p =0.006) were significantly correlated with the number of SCIs. Among smokers, the number of SCIs was significantly higher in current smokers than in past smokers (1.9+/-2.2 vs. 0.5+/-0.8, p <0.01). In multiple regression analysis, smoking status (beta =0.183, p =0.045) and SBP (beta =0.196, p =0.011) were independent determinants of the increased number of SCIs. In conclusion, smoking status was an independent determinant of multiple SCIs in a high-risk Japanese community-dwelling population.

Olmesartan Improves Endothelin-Induced Hypertension and Oxidative Stress in Rats

Recent studies have indicated that both endothelin (ET) and angiotensin (Ang) II stimulate oxidative stress, which contributes to the development of hypertension. Here, we examined the effects of Ang II type 1 (AT1) receptor blockade on reactive oxygen species (ROS) formation in ET-dependent hypertension. Chronic ET-1 infusion (2.5 pmol/kg/min, i.v., n=7) into rats for 14 days increased systolic blood pressure from 113+/-1 to 141+/-2 mmHg. ET-1-infused rats showed greater plasma renin activity (8.1+/-0.8 Ang I/ml/h), and greater Ang I (122+/-28 fmol/ml) and Ang II levels (94+/-13 fmol/ml) than vehicle (0.9% NaCl)-infused rats (3.1+/-0.6 Ang I/ml/h, 45+/-8 and 47+/-7 fmol/ml, respectively, n=6). Angiotensin converting enzyme and AT1 receptor expression in aortic tissues were similar between the vehicle- and ET-1-infused rats. Vascular superoxide anion (O2-) production and plasma thiobarbituric acid-reactive substance (TBARS) levels were greater in ET-1-infused rats (27+/-1 counts per minutes [CPM]/mg dry tissue weight and 8.9+/-0.8 micromol/l, respectively) than vehicle-infused rats (16+/-1 CPM/mg and 5.1+/-0.1 micromol/l, respectively). The ET-1-induced hypertension was prevented by simultaneous treatment with a new AT1 receptor antagonist, olmesartan (0.01% in chow, 117+/-5 mmHg, n =7), or hydralazine (15 mg/kg/day in drinking water, 118+/-4 mmHg, n=6). Olmesartan prevented ET-1-induced increases in vascular O2- production (15+/-1 CPM/mg) and plasma TBARS (5.0+/-0.1 micromol/l). Vascular O2- production and plasma TBARS were also decreased by hydralazine (21+/-1 CPM/mg and 7.0+/-0.3 micromol/l, respectively), but these levels were significantly higher than in vehicle-infused rats. These data suggest that ET-dependent hypertension is associated with augmentation of Ang II levels and ROS formation. The combined effects of the elevations in circulating ET-1 and Ang II, as well as the associated ROS production, may contribute to the development of hypertension induced by chronic ET-1 infusion.