Endothelium plays a fundamental role in the cardiovascular system, forming an interface between blood and adjacent tissues by regulating the vascular tone through the synthesis of nitric oxide, prostaglandins and other relaxing factors. Endothelial dysfunction is characterized by vasoconstriction, cell proliferation and shifting toward a proinflammatory and prothrombic state. In hypertension endothelial dysfunction may be involved in the initiation and development of vascular inflammation, vascular remodeling, and atherosclerosis and is independently associated with increased cardiovascular risk. Different conditions such as impaired vascular shear stress, inflammation and oxidative stress, activation of the renin angiotensin system have been described as important pathophysiological mechanisms involved in the development of endothelial dysfunction. The release of extracellular vesicles by neighboring cells in the vascular wall has emerged as an important regulator of endothelial function and with potential antihypertensive properties and beneficial effects by counteracting the hypertension mediated organ damage. Furthermore, macrovesicles are emerging as an innovative therapeutic approach for vascular protection, allowing the delivery of bioactive molecules, such as miRNA and drugs interacting with the renin angiotensin system. In this review we summarize the available evidence about the pathophysiological implications of endothelial dysfunction in cardiovascular diseases, focusing on hypertension and its sequelae, and the potential innovative therapeutic strategies targeting the endothelium with the aim to improve vascular function and remodeling.

Background— Enhanced production of reactive oxygen species (ROS) has been recognized as the major determinant of age-related endothelial dysfunction. The p66 ^shc protein controls cellular responses to oxidative stress. Mice lacking p66 ^shc (p66 ^shc−/− ) have increased resistance to ROS and a 30% prolonged life span. The present study investigates age-dependent changes of endothelial function in this model. Methods and Results— Aortic rings from young and old p66 ^shc−/− or wild-type (WT) mice were suspended for isometric tension recording. Nitric oxide (NO) release was measured by a porphyrinic microsensor. Expression of endothelial NO synthase (eNOS), inducible NOS (iNOS), superoxide dismutase, and nitrotyrosine-containing proteins was assessed by Western blotting. Nitrotyrosine residues were also identified by immunohistochemistry. Superoxide (O ₂ ⁻ ) production was determined by coelenterazine-enhanced chemiluminescence. Endothelium-dependent relaxation in response to acetylcholine was age-dependently impaired in WT mice but not in p66 ^shc−/− mice. Accordingly, an age-related decline of NO release was found in WT but not in p66 ^shc−/− mice. The expression of eNOS and manganese superoxide dismutase was not affected by aging either in WT or in p66 ^shc−/− mice, whereas iNOS was upregulated only in old WT mice. It is interesting that old WT mice displayed a significant increase of O ₂ ⁻ production as well as of nitrotyrosine expression compared with young animals. Such age-dependent changes were not found in p66 ^shc−/− mice. Conclusions— We report that inactivation of the p66 ^shc gene protects against age-dependent, ROS-mediated endothelial dysfunction. These findings suggest that the p66 ^shc is part of a signal transduction pathway also relevant to endothelial integrity and may represent a novel target to prevent vascular aging.

More than 80% of patients with type 2 diabetes mellitus develop hypertension, and approx. 20% of patients with hypertension develop diabetes. This combination of cardiovascular risk factors will account for a large proportion of cardiovascular morbidity and mortality. Lowering elevated blood pressure in diabetic hypertensive individuals decreases cardiovascular events. In patients with hypertension and diabetes, the pathophysiology of cardiovascular disease is multifactorial, but recent evidence points toward the presence of an important component dependent on a low-grade inflammatory process. Angiotensin II may be to a large degree responsible for triggering vascular inflammation by inducing oxidative stress, resulting in up-regulation of pro-inflammatory transcription factors such as NF-κB (nuclear factor κB). These, in turn, regulate the generation of inflammatory mediators that lead to endothelial dysfunction and vascular injury. Inflammatory markers (e.g. C-reactive protein, chemokines and adhesion molecules) are increased in patients with hypertension and metabolic disorders, and predict the development of cardiovascular disease. Lifestyle modification and pharmacological approaches (such as drugs that target the renin–angiotensin system) may reduce blood pressure and inflammation in patients with hypertension and metabolic disorders, which will reduce cardiovascular risk, development of diabetes and cardiovascular morbidity and mortality.

In this review we summarize the recent evidence that highlights the involvement of low-grade inflammation in the development and pathophysiology of hypertension. Essential hypertension is characterized by increased peripheral vascular resistance to blood flow, due in large part to vascular remodeling. Vascular changes in hypertension are associated with mechanical and humoral factors that modulate signaling events, resulting in abnormal function, media growth, extracellular matrix deposition and inflammation. Recent evidence suggests that inflammation is present in the vasculature in animal models of hypertension. Inflammatory markers, such as C-reactive protein, are associated with vascular lesions in humans, and are predictive of cardiovascular outcome. In animal and human studies, pro-inflammatory components of the renin-angiotensin-aldosterone system have been demonstrated in large conduit and small arteries in the kidney and heart. Peroxisome proliferator-activated receptor activators are drugs with metabolic properties that have been demonstrated to exert anti-inflammatory effects on the vasculature, and there is now evidence that these actions may be protective for blood vessels. Inflammatory processes are important participants in the pathophysiology of hypertension and cardiovascular disease. The identification of the mechanisms leading to the activation of inflammation should contribute to the development of specific therapeutic approaches to apply in hypertension and its complications.

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.

Magnesium modulates vascular smooth muscle cell (VSMC) function. However, molecular mechanisms regulating VSMC Mg ²⁺ remain unknown. Using biochemical, pharmacological, and genetic tools, the role of transient receptor potential membrane melastatin 7 (TRPM7) cation channel in VSMC Mg ²⁺ homeostasis was evaluated. Rat, mouse, and human VSMCs were studied. Reverse transcriptase polymerase chain reaction and immunoblotting demonstrated TRPM7 presence in VSMCs (membrane and cytosol). Angiotensin II (Ang II) and aldosterone increased TRPM7 expression. Gene silencing using small interfering RNA (siRNA) against TRPM7, downregulated TRPM7 (mRNA and protein). Basal [Mg ²⁺ ] _i , measured by mag fura-2AM, was reduced in siRNA-transfected cells (0.39±0.01 mmol/L) versus controls (0.54±0.01 mmol/L; P <0.01). Extracellular Mg ²⁺ dose-dependently increased [Mg ²⁺ ] _i in control cells (E _max 0.70±0.02 mmol/L) and nonsilencing siRNA-transfected cells (E _max 0.71±0.04 mmol/L), but not in siRNA-transfected cells (E _max 0.5±0.01 mmol/L). The functional significance of TRPM7 was evaluated by assessing [Mg ²⁺ ] _i and growth responses to Ang II in TRPM7 knockdown cells. Acute Ang II stimulation decreased [Mg ²⁺ ] _i in control and TRPM7-deficient cells in a Na ⁺ -dependent manner. Chronic stimulation increased [Mg ²⁺ ] _i in control, but not in siRNA-transfected VSMCs. Ang II–induced DNA and protein synthesis, measured by ³ [H]-thymidine and ³ [H]-leucine incorporation, respectively, were increased in control and nonsilencing cells, but not in TRPM7 knockdown VSMCs. Our data indicate that VSMCs possess membrane-associated, Ang II–, and aldosterone-regulated TRPM7 channels, which play a role in regulating basal [Mg ²⁺ ] _i , transmembrane Mg ²⁺ transport and DNA and protein synthesis. These novel findings identify TRPM7 as a functionally important regulator of Mg ²⁺ homeostasis and growth in VSMCs.