Collagen I and III mRNA gene expression and cell growth potential of skin fibroblasts in patients with essential hypertension

CpG methylation changes in Alu repetitive sequences in normal aging due to diastolic hypertension in human dermal fibroblasts from the facial area

Aging fibroblasts, an important factor contributing to skin aging, are affected by numerous mechanisms, including alterations in DNA methylation and age-related diseases. The current study aimed to investigate the role of Alu methylation in aging fibroblasts and hypertension. The Alu methylation levels in dermal fibroblasts obtained from patients of different ages and blood pressure status were analyzed using the combined bisulfite restriction analysis technique. An inverse correlation was observed between Alu methylation in dermal fibroblasts and patient age. Dermal fibroblasts from the high-normal diastolic blood pressure group had higher Alu methylation levels compared with those from the normal group. The findings of the present study suggest that Alu methylation alterations can be observed with chronological aging and hypertension, and are a potential aging marker or therapeutic target.

Angiotensin II and vascular injury

Vascular injury, characterized by endothelial dysfunction, structural remodelling, inflammation and fibrosis, plays an important role in cardiovascular diseases. Cellular processes underlying this include altered vascular smooth muscle cell (VSMC) growth/apoptosis, fibrosis, increased contractility and vascular calcification. Associated with these events is VSMC differentiation and phenotypic switching from a contractile to a proliferative/secretory phenotype. Inflammation, associated with macrophage infiltration and increased expression of redox-sensitive pro-inflammatory genes, also contributes to vascular remodelling. Among the many factors involved in vascular injury is Ang II. Ang II, previously thought to be the sole biologically active downstream peptide of the renin-angiotensin system (RAS), is converted to smaller peptides, [Ang III, Ang IV, Ang-(1-7)], that are functional and that modulate vascular tone and structure. The actions of Ang II are mediated via signalling pathways activated upon binding to AT1R and AT2R. AT1R activation induces effects through PLC-IP3-DAG, MAP kinases, tyrosine kinases, tyrosine phosphatases and RhoA/Rho kinase. Ang II elicits many of its (patho)physiological actions by stimulating reactive oxygen species (ROS) generation through activation of vascular NAD(P)H oxidase (Nox). ROS in turn influence redox-sensitive signalling molecules. Here we discuss the role of Ang II in vascular injury, focusing on molecular mechanisms and cellular processes. Implications in vascular remodelling, inflammation, calcification and atherosclerosis are highlighted.

Effects of six months of vitamin D supplementation in patients with heart failure: a randomized double-blind controlled trial

BACKGROUND AND AIM

Low plasma vitamin D levels have been associated with heart failure (HF). This research attempts to explain the role of vitamin D supplementation on myocardial function in elderly patients with HF.

METHODS AND RESULTS

Twenty-three chronic HF patients were randomized in a small parallel group, double-blind, placebo-controlled trial. All patients, with a mean age of 74 years and vitamin D levels <30 ng/mL, received 800,000 IU (4000 IU/daily) of cholecalciferol or placebo for 6 months. The outcomes measured at baseline and after 6 months were ejection fraction (EF) and other echocardiography parameters, carboxyterminal propeptide of procollagen type I (PIP), natriuretic peptides, lipid profile, renin, parathyroid hormone, blood pressure, and body mass index (BMI). In 13 patients under active treatment for 6 months, mean plasma 25-hydroxy vitamin D concentrations (15.51 vs. -1.40 ng/mL, p < 0.001) and plasma calcium (from 9.3 to 9.6 mmol/L, p < 0.05) increased significantly. However, other biomarkers of bone metabolism did not differ between the treatment and placebo groups. EF increased significantly in the intervention group (6.71 vs. -4.3%; p < 0.001), and the serum concentration of PIP increased only in the placebo group after 6 months (1140.98 vs. -145 mcg/L; p < 0.05). Systolic blood pressure was lower after 6 months of cholecalciferol treatment (from 129.6 to 122.7 mm Hg, p < 0.05). No significant variations were observed for other parameters.

CONCLUSIONS

Six months of vitamin D supplementation significantly improves EF in elderly patients with HF and vitamin D deficiency.

Angiotensin II and the vascular phenotype in hypertension

Hypertension is associated with vascular changes characterised by remodelling, endothelial dysfunction and hyperreactivity. Cellular processes underlying these perturbations include altered vascular smooth muscle cell growth and apoptosis, fibrosis, hypercontractility and calcification. Inflammation, associated with macrophage infiltration and increased expression of redox-sensitive pro-inflammatory genes, also contributes to vascular remodelling. Many of these features occur with ageing, and the vascular phenotype in hypertension is considered a phenomenon of ‘premature vascular ageing’. Among the many factors involved in the hypertensive vascular phenotype, angiotensin II (Ang II) is especially important. Ang II, previously thought to be the sole effector of the renin–angiotensin system (RAS), is converted to smaller peptides [Ang III, Ang IV, Ang-(1-7)] that are biologically active in the vascular system. Another new component of the RAS is the (pro)renin receptor, which signals through Ang-II-independent mechanisms and might influence vascular function. Ang II mediates effects through complex signalling pathways on binding to its G-protein-coupled receptors (GPCRs) AT1R and AT2R. These receptors are regulated by the GPCR-interacting proteins ATRAP, ARAP1 and ATIP. AT1R activation induces effects through the phospholipase C pathway, mitogen-activated protein kinases, tyrosine kinases/phosphatases, RhoA/Rhokinase and NAD(P)H-oxidase-derived reactive oxygen species. Here we focus on recent developments and new research trends related to Ang II and the RAS and involvement in the hypertensive vascular phenotype.

Specific inflammatory condition in nucleus tractus solitarii of the SHR: novel insight for neurogenic hypertension?

Human essential hypertension is a complex polygenic trait with underlying genetic components that remain unknown. Since the brainstem structure--the nucleus of the solitary tract (NTS)--is a pivotal region for regulating the set-point of arterial pressure, we proposed a role for it in the development of primary hypertension. Using microarray and real-time RT-PCR, we have recently identified that some pro-inflammatory molecules, such as junctional adhesion molecule-1 (JAM-1; a leukocyte/platelet adhesion molecule), were over expressed in endothelial cells in the NTS of an animal model of human essential hypertension--the spontaneously hypertensive rat (SHR) compared to normotensive Wistar Kyoto rats (WKY). Adenoviral mediated over expression of JAM-1 in NTS of WKY rats produced both hypertension and localized leukocyte adherence to the microvasculature. With a known effect of leukocyte adhesion causing cytokine release, we predicted differences in the level of gene expression of cytokines in the NTS of SHR relative to WKY. Gene expression of monocyte chemoattractant protein-1 (MCP-1) was higher in the NTS of SHR while inter-leukin-6 (IL-6) was lower in the NTS of SHR compared to the WKY. Because both inflammatory molecules are known to affect neural functions, our data suggest that the microvasculature of NTS of the SHR exhibits a specific inflammatory state. We propose a new hypothesis that as a consequence of enhanced expression of leukocyte adhesion molecules within the microvasculature of NTS there is a specific inflammatory response that leads to cardiovascular autonomic dysfunction contributing to neurogenic hypertension.

Junctional Adhesion Molecule-1 Is Upregulated in Spontaneously Hypertensive Rats

Junctional adhesion molecule-1 (JAM-1) forms part of the tight junction between adjacent endothelial cells. Using microarray technology, we showed previously that JAM-1 was differentially expressed in the brain stem of spontaneously hypertensive rats compared with normotensive Wistar-Kyoto (WKY) rats. In this study, we quantified the expression of JAM-1 in the brain stem of spontaneously hypertensive rats and WKY rats and established whether any differential expression was confined to this region of the brain or was ubiquitous throughout the central nervous system and, indeed, the whole body. Because the nucleus tractus solitarii plays a pivotal role in arterial pressure regulation, we assessed whether JAM-1 in this region affects the chronic regulation of arterial pressure. Real time RT-PCR revealed that JAM-1 mRNA was upregulated in multiple regions of the brain and all of the peripheral vascular beds studied. In the nucleus tractus solitarii, the level of JAM-1 mRNA was significantly higher in both young (3-week-old, prehypertensive) and adult male spontaneously hypertensive rats (15 to 18 weeks old) than that of age-matched WKY rats (fold differences; prehypertensives: 1.01+/-0.06 versus 1.59+/-0.13; n=10; P<0.01; adult: 1.08+/-0.14 versus 2.86+/-0.57; n=10; P<0.01). After adenoviral-mediated expression of JAM-1 in the nucleus tractus solitarii of adult WKY rats (15 weeks old; n=6), systolic pressure was increased from 120+/-4 to 132+/-4 mm Hg (P<0.01). Our data suggest that JAM-1 expression in the spontaneously hypertensive rat is upregulated throughout the body compared with the WKY rat and that this is not secondary to the hypertension. When JAM-1 is expressed in the nucleus tractus solitarii, it raises arterial pressure, suggesting a novel prohypertensive role for this protein within the brain stem.

Losartan improves resistance artery lesions and prevents CTGF and TGF-beta production in mild hypertensive patients

Although structural and functional changes of resistance arteries have been proposed to participate in arterial hypertension (HTA) outcome, not all therapies may correct these alterations, even if they normalize the blood pressure (BP). The aim of this study was to investigate the mechanisms of the protection afforded by the angiotensin receptor antagonist losartan in resistance arteries from patients with essential HTA. In all, 22 untreated hypertensive patients were randomized to receive losartan or amlodipine for 1 year and the morphological characteristics of resistance vessels from subcutaneous biopsies were evaluated. Protein expression of connective tissue growth factor (CTGF), transforming growth factor beta (TGF-beta), and collagens III and IV was detected by immunohistochemistry. In comparison with normotensive subjects, resistance arteries from hypertensive patients showed a significant media:lumen (M/L) ratio increment and a higher protein expression of CTGF, TGF-beta, and collagens. After 1 year of treatment, both losartan and amlodipine similarly controlled BP. However, M/L only decreased in patients under losartan treatment, whereas in the amlodipine-treated group this ratio continued to increase significantly. The administration of losartan prevented significant increments in CTGF, TGF-beta, and collagens in resistance arteries. By contrast, amlodipine-treated patients showed a higher vascular CTGF, TGF-beta, and collagen IV staining than before treatment. Our results show that the administration of losartan, but not amlodipine, to hypertensive patients improves structural abnormalities and prevents the production of CTGF and TGF-beta in small arteries, despite similar BP lowering. These data may explain the molecular mechanisms of the better vascular protection afforded by drugs interfering with the renin-angiotensin system.

Stiffness of the arterial wall, joints and skin in women with a history of pre-eclampsia

OBJECTIVE

The epidemiology of pre-eclampsia suggests a constitutional component for the disorder. We have recently shown an association for blood pressure (BP) with stiffness of joints and skin in adolescents, suggesting that constitutionally determined stiffness of body tissues is associated with blood pressure. Therefore, we compared stiffness of the arterial wall, joints and skin between women with a history of pre-eclampsia and women with an uncomplicated pregnancy.

DESIGN

Cases were 44 women with a history of early onset pre-eclampsia and controls were 46 women with a history of uncomplicated pregnancy. Arterial stiffness was determined non-invasively with pulse wave velocity measurement. As a measure of capsule and ligament stiffness, the active range of motion of various joints was measured. Skin stiffness was measured using a tissue compliance meter. Analysis of variance (ANOVA) multiple comparison tests were used for comparison of the study groups. Linear regression models were used to determine the associations between stiffness parameters and possible confounders.

RESULTS

For the cases, body mass index (BMI) was significantly higher and age and parity were significantly lower. BP was significantly higher for the cases. Stiffness of the arterial wall, joints and skin were significantly higher. After adjustment for mean arterial pressure, stiffness of the joints and skin were significantly higher, but no difference remained for arterial stiffness.

CONCLUSIONS

Women with a history of pre-eclampsia had a significantly higher stiffness of the arterial wall, joints and skin compared with controls. This suggests a constitutionally determined stiffness of connective tissues in former pre-eclamptic cases.

Differential effect of experimental hypertension and hypercholesterolemia on adventitial remodeling

OBJECTIVE

Intima-media remodeling, as frequently assessed by changes in the external elastic lamina-to-lumen area (EELLA), is well-described in coronary artery disease in contrast to adventitial remodeling, especially in the early disease stage.

METHOD AND RESULTS

Female domestic pigs were randomized to one of the following 12-week treatment groups: normal diet (N; n=6), high-cholesterol diet (HC; n=6), or renovascular hypertension (HT; n=4). Low-density lipoprotein (LDL) cholesterol serum concentration was higher in HC than in N and HT (395.5+/-106 versus 38.6+/-14 and 37.2+/-6.8 mg/dL; P<0.05 for both). Mean arterial pressure was higher in HT than in N and HC (141.3+/-21 versus 107.4+/-8.9 and 109.4+/-7.8 mm Hg; P<0.05 for both). EELLA ratio, as assessed by morphometry, was similar in N, HC, and HTN (1.03+/-0.32 versus 0.95+/-0.29 and 1.01+/-0.09; P<0.05 for both). Coronary vasa vasorum density, as assessed by 3-dimensional micro-computed tomography, was higher in HC than in N and HT (3.4+/-1.0 versus 1.9+/-0.3 and 2.0+/-1.2; P<0.05 for both). In contrast, immunostaining showed a higher collagen III content and the presence of adventitial myofibroblasts in HT compared with N and HC.

CONCLUSIONS

The current study suggests that adventitial remodeling precedes intima and media remodeling of coronary arteries early after exposure to hypercholesterolemia and hypertension, with distinct qualitative differences between them. Intima-media remodeling is well-described in coronary artery disease in contrast to adventitial remodeling. Results of the current study on coronary arteries of pigs, randomized to 12 weeks of normal diet (N), hypercholesterolemic diet (HC), or renovascular hypertensive (HT), indicate that adventitial remodeling precedes intima-media remodeling early after risk factor exposure with distinct qualitative differences.

The role of angiotensin II in regulating vascular structural and functional changes in hypertension

A major hemodynamic abnormality in hypertension is increased peripheral resistance due to changes in vascular structure and function. Structural changes include reduced lumen diameter and arterial wall thickening. Functional changes include increased vasoconstriction and/or decreased vasodilation. These processes are influenced by many humoral factors, of which angiotensin II (Ang II) seems to be critical. At the cellular level, Ang II stimulates vascular smooth muscle cell growth, increases collagen deposition, induces inflammation, increases contractility, and decreases dilation. Molecular mechanisms associated with these changes in hypertension include upregulation of many signaling pathways, including tyrosine kinases, mitogen-activated protein kinases, RhoA/Rho kinase, and increased generation of reactive oxygen species. This review focuses on the role of Ang II in vascular functional and structural changes of small arteries in hypertension. In addition, cellular processes whereby Ang II influences vessels in hypertension are discussed. Finally, novel concepts related to signaling pathways by which Ang II regulates vascular smooth muscle cells in hypertension are introduced.