Liliana Legedz

N-Terminal Pro-Brain Natriuretic Peptide: A Powerful Predictor of Mortality in Hypertension

See Editorial Commentary, pp 670–671Natriuretic peptides are controregulatory hormones associated with cardiac remodeling, namely, left ventricular hypertrophy and systolic/diastolic dysfunction. We intended to address the prognostic value of N-terminal pro-brain natriuretic peptide (NT-proBNP) in hypertension. We prospectively studied the relationship between plasma NT-proBNP and all-cause mortality in 684 hypertensive patients with no history or symptoms of heart failure referred for hypertension workup in our institution from 1998 to 2008. After a mean duration of 5.7 years, we observed 40 deaths (1.04 deaths per 100 patients per year). After adjustment for traditional cardiovascular risk factors, including ambulatory blood pressure and serum creatinine, the risk for all-cause mortality more than doubled with each increment of 1 log NT-proBNP (hazard ratio: 2.33 [95% CI: 1.36 to 3.96]). The risk of death of patients with plasma NT-proBNP ≥133 pg/mL (third tertile of the distribution) was 3.3 times that of patients with values <50.8 pg/mL (first tertile; hazard ratio: 3.30 [95% CI: 0.90 to 12.29]). This predictive value was independent of, and superior to, that of 2 ECG indexes of left ventricular hypertrophy, the Sokolov-Lyon index and the amplitude of the R wave in lead aVL. In addition, it persisted in patients without ECG left ventricular hypertrophy, which allowed refining risk stratification in this relatively low-risk patient category. In this large sample of hypertensive patients, plasma NT-proBNP appeared as a strong prognostic marker. This performance, together with the ease of measurement, low cost, and widespread availability of NT-proBNP test kits, should prompt a wide use of this marker for risk stratification in hypertension.

Genes of Cholesterol Metabolism in Human Atheroma: Overexpression of Perilipin and Genes Promoting Cholesterol Storage and Repression of ABCA1 Expression

Objective—Accumulation of cholesterol in foam cells of atheroma plaques depends on the balance between uptake and efflux of cholesterol. It may also depend on proteins surrounding lipid droplets, adipophilin, and perilipins. They favor triglyceride storage in adipocytes and could play a similar role for cholesterol in atheroma. Methods and Results—We measured in human atheroma and nearby macroscopically intact tissue (MIT) the expression of perilipin, adipophilin, and regulatory factors of cholesterol metabolism. We identified perilipin A in human arterial wall. Its expression was largely increased in atheroma compared with MIT, and perilipin was present in macrophages and vascular smooth muscle cells. Adipophilin, ACAT1, and CD36 were also overexpressed in atheroma. mRNA levels of low-density lipoprotein receptor, 3-hydroxy-3-methylglutaryl coenzyme A reductase, and SREBP-2 were unchanged. With respect to efflux of cholesterol, the mRNA levels of NCEH and ABCA-1 were unchanged, whereas CLA-1 mRNA was slightly higher in atheroma. Importantly, immunoblotting of ABCA-1 showed a dramatic decrease of ABCA1 protein, the key molecule of cholesterol efflux, in atheroma compared with MIT. Conclusion—We show the presence and induction of perilipin in atheroma. This overexpression and the coordinated modifications of expression of key regulatory factors for cholesterol metabolism could favor cholesterol accumulation.

Effect of abdominal aortic grafts on aortic stiffness and central hemodynamics

Graft-prosthesis and stentgraft placements are effective modalities for treating abdominal aortic aneurysm, but related changes in arterial stiffness are not well established. The present study sought to assess aortic stiffness after aneurism repair by measuring pulse wave velocity (PWV). The graft-related variation of carotid–femoral PWV was compared with that of carotid–radial PWV, the latter being unaffected by vascular treatment. The secondary objective was to evaluate potential differences between graft-prosthesis and stentgraft in terms of aortic stiffness and augmentation index, a composite indicator integrating wave reflexion. Fifty patients were included (39 had a graft-prosthesis and 11 had a stentgraft). In the whole group and after a median postoperative follow-up of 47 days, carotid–femoral PWV increased by +1.0 m/s [−12.3, +10.3], while carotid–radial PWV slightly decreased by −0.3 m/s [−4.4; +3.5] (P = 0.001). The effect of the type of prosthesis on the PWV was not significant. Nevertheless, the augmentation index increased after stentgraft implantation (+4% [−10; +17]) and decreased after graft-prosthesis placement (−8.5% [−47; +17]) (P < 0.01). This difference was not explained by a heart rate or a treatment effect and was likely attributable to the prosthesis per se. This study demonstrates the impact of aortic grafts on aortic stiffness. Besides, it suggests that stentgraft increases reflected waves more than graft-prostheses. These changes of vascular properties may influence the outcomes after surgery.

Arterial stiffness is associated with left atrial size in hypertensive patients

BACKGROUND Arterial stiffness is a strong predictor of cardiovascular events and particularly of stroke. A likely explanation is the development of atherosclerotic lesions at the carotid level, favored by increased local stiffness. Another possibility involves cardiac consequences of aortic stiffness and particularly left atrial dilatation with its subsequent risk of atrial fibrillation (AF) and cerebral embolism. AIMS The present study investigated the link between arterial stiffness, pulse pressure and left atrial size, a determinant of AF risk. METHODS Arterial stiffness was determined from pulse wave velocity (PWV) and pulse pressure (PP). Left atrial size was also measured. Several potential confounders were taken into account including indices of ventricular remodeling and diastolic function (estimated by NT-Pro brain natriuretic peptide (NT-proBNP) levels). RESULTS Three-hundred and ten hypertensive patients, aged 53 +/- 13 years, were included. Mean 24-h blood pressure (BP) was 154 +/- 20 over 93 +/- 13 mmHg. Significant relationships were found between left atrial diameter (LAD) and PWV (r=0.27, P<0.001) and between LAD and 24-h PP (r=0.32, P<0.001). LAD was also correlated significantly, although not always tightly, with left ventricular dimensions, geometry and NT-proBNP. In two different multivariate models, LAD remained significantly correlated with PWV or with 24-h PP, independently of classical determinants like age, gender, body mass index, ventricular remodeling (i.e. dimensions and geometry) and filling pressure. CONCLUSION These results led us to propose AF as a new possible pathophysiological link between arterial stiffness and stroke. These results also emphasize the cardiac consequences of arterial stiffness which can fuel a new approach to AF prevention.

Cathepsin G is associated with atheroma formation in human carotid artery.

Objective To elucidate the organization of the tissue angiotensin system, we investigated the expression and cellular localization of angiotensin system components and cathepsins D and G, potentially involved in intraparietal angiotensin II formation and atheroma. Methods Total RNA was extracted from atheroma plaque, fatty streaks and macroscopically intact tissue obtained during carotid endarterectomy in 21 hypertensive patients. mRNA levels were compared between these tissues using a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). In situ hybridization and immunohistochemistry were used to define the cellular localization of the transcripts and their respective proteins. Results Apart from renin and angiotensin type 2 (AT2) receptors, which were never detected, the studied mRNAs could be measured in all patients. Angiotensin-converting enzyme (ACE) mRNA was increased five-fold in atheroma, and angiotensin type 1 receptor (AT1) mRNA decreased 2.5-fold in atheroma and 1.4-fold in fatty streaks compared to intact tissue. A two-fold increase in cathepsin G mRNA was observed in atheroma plaque. In atheroma and intact tissue, significant positive correlations were found between cathepsin G and angiotensinogen, AT1 receptor and ACE mRNAs. Angiotensinogen and cathepsin mRNAs and proteins were detected in both arterial layers. AT1 immunoreactivity was mainly associated with α-actin-positive cells. Conclusion All components required for angiotensin II formation are expressed locally in the arterial wall, where, in the absence of renin, cathepsin G could be a major angiotensin-generating enzyme. Overexpression of ACE and cathepsin G may lead to angiotensin II overproduction and contribute, with decreased number of differentiated smooth muscle cells, to the lower amount of AT1 receptor in atheroma.

Increased Insulin-Stimulated Expression of Arterial Angiotensinogen and Angiotensin Type 1 Receptor in Patients With Type 2 Diabetes Mellitus and Atheroma

Objective—Because inhibition of the renin–angiotensin system (RAS) reduces the onset of type 2 diabetes (T2D) and prevents atherosclerosis, we investigated the expression of RAS in the arterial wall of T2D and nondiabetic (CTR) patients. Methods and Results—mRNA and protein levels of angiotensinogen (AGT), angiotensin-converting enzyme (ACE) and AT1 receptor (AT1R) were determined in carotid atheroma plaque, nearby macroscopically intact tissue (MIT), and in vascular smooth muscle cells (VSMCs) before and after insulin stimulation from 21 T2D and 22 CTR patients. AGT and ACE mRNA and their protein levels were 2- to 3-fold higher in atheroma and in MIT of T2D patients. VSMCs from T2D patients had respectively 2.5- and 5-fold higher AGT and AT1R mRNA and protein contents. Insulin induced an increase in AGT and AT1R mRNA with similar ED50. These responses were blocked by PD98059, an inhibitor of MAP-kinase in the two groups whereas wortmannin, an inhibitor of PI3-kinase, partially prevented the response in CTR patients. Phosphorylated ERK1–2 was 4-fold higher in MIT from T2D than from CTR patients. Conclusions—The arterial RAS is upregulated in T2D patients, which can be partly explained by an hyperactivation of the ERK1–2 pathway by insulin.

Outcome Associations of Carotid-Femoral Pulse Wave Velocity Vary With Different Measurement Methods

BACKGROUND The impact of various methods of travel distance estimation on the prognostic value of pulse wave velocity (PWV) and on the adequacy of cut-offs has never been addressed within a single population of hypertensive patients. METHODS Four carotid-femoral PWVs were calculated from four different travel distances (Direct, Real, Subtracted, and Estimated) divided by the same travel time in 426 hypertensives (mean age 51.2 ± 13.8 years, mean systolic blood pressure 155.6 ± 21.1 mm Hg). The incidence of death from any cause and major cardiovascular events was studied. PWV predictive accuracies were determined using C-index analysis. Hazard ratios (HRs) associated with specific values of PWV were determined with Cox model analyses using cubic splines. RESULTS Mean PWV ranged from 8.3 ± 2.3 m/s for the Subtracted one to 11.6 ± 3.0 m/s for the Direct one (P < 0.001). When included as continuous variables in a Cox model, the four PWVs were significantly associated with outcome (all P < 0.001), and had similar C-index (0.608-0.617). In multivariable analysis, the HR calculated for a Direct PWV of 12 m/s was neutral (HR = 1.02). In contrast, the same analysis provided HR ranging from 1.79 to 2.90 with the other PWVs. CONCLUSIONS Different travel distances markedly impact PWV values and prognostic cut-offs. PWV cut-offs should consequently be ascertained jointly with the method of measurement used. There is an urgent need for standardization of PWV assessment before implementing this parameter in the routine management of hypertensives.

Significance of urinary angiotensinogen in essential hypertension as a function of plasma renin and aldosterone status.

Objective This study was performed to test the significance of urinary angiotensinogen (UAGT) in essential hypertensive patients stratified as a function of plasma renin and aldosterone. Methods and results A sample of 248 essential hypertensives, investigated under their usual sodium diet and either off-medication or under a standardized treatment, was separated into two groups on the basis of upright plasma active renin and aldosterone medians. Patients with plasma active renin and aldosterone below medians are referred to as the low renin–aldosterone essential hypertensive group (LRA-EH). Others subjects are defined as other essential hypertensives (O-EH). Blood pressure (BP) was recorded by 24-h ambulatory monitoring. UAGT was measured by a specific enzyme-linked immunosorbent assay for total angiotensinogen. Because UAGT was markedly increased in the presence of overt proteinuria (≥ 300 mg/24 h), proteinuric patients (n = 29) were excluded from subsequent analyses. UAGT was a significant predictor of systolic and diastolic BP in LRA-EH females (P < 0.01 and P = 0.05, respectively) but not in males. By contrast, urinary sodium excretion (P < 0.001) and maintenance of treatment (P = 0.002) were significant predictors of systolic BP in males. These correlations were not observed in O-EH, whether males or females. Conclusions In the present study, UAGT stands as a strong predictor of BP in women with low plasma renin/aldosterone, suggesting an involvement of the tubular renin–angiotensin system in these subjects. Higher sodium intake or the need to maintain treatment may account in part for the lack of a similar relationship in males.

Induction of tissue kallikrein in human carotid atheroma does not lead to kallikrein-kinins pathway activation.

Objective The impairment of the tissue kallikrein-kinin system (KKS) may result in atheroma development. To determine the involvement of KKS in pathophysiology of human atherosclerosis, we examined the expression of all components of this system as well as angiotensinogen (another tissue kallikrein (TK) substrate), at messenger ribonucleic acid (mRNA) and protein levels in the human carotid artery with and without atheroma. Methods mRNA levels were compared with semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) between atheroma plaque and intact tissue obtained during carotid endarterectomy in 15 patients. The cellular localization of the transcripts and proteins was analyzed with in situ hybridization and immunohistochemistry. TK activity was measured using chromogenic substrate. Results The kininogen mRNA was not detected in carotid wall. The TK mRNA was increased four-fold and TK activity 23-fold in atheroma plaque compared with intact tissue. No difference was observed for B1, B2 receptors, kallistatin, angiotensinogen and protein-kinase G type 1α (PK-G) mRNAs. The TK and angiotensinogen transcripts as well as kininogen and angiotensinogen proteins were present in both intimal and medial cells. The kininogen immunoreactivity was weaker in atheroma. Conclusions All KKS components were synthesized in arterial wall except kininogen probably coming from plasma. The absence of PK-G mRNA down-regulation in atheroma suggests that the kallikrein induction does not lead to KKS activation.

Local Angiotensin Pathways in Human Carotid Atheroma: Towards a Systems Biology Approach

We will summarize the data we have obtained in human carotid artery concerning the organization of an extended local renin angiotensin aldosterone system and its variations at different stages of atheroma. In a system view, we propose a model where concomitant increase in angiotensin and glucocorticoid signaling is induced and amplified in VSMC while vascular smooth muscle cells transdifferentiate toward a lipid storing phenotype.