Vascular stiffness is a mechanical property of the vessel wall that affects blood pressure, permeability, and inflammation. As a result, vascular stiffness is a key driver of (chronic) human disorders, including pulmonary arterial hypertension, kidney disease, and atherosclerosis. Responses of the endothelium to stiffening involve integration of mechanical cues from various sources, including the extracellular matrix, smooth muscle cells, and the forces that derive from shear stress of blood. This response in turn affects endothelial cell contractility, which is an important property that regulates endothelial stiffness, permeability, and leukocyte-vessel wall interactions. Moreover, endothelial stiffening reduces nitric oxide production, which promotes smooth muscle cell contraction and vasoconstriction. In fact, vessel wall stiffening, and microcirculatory endothelial dysfunction, precedes hypertension and thus underlies the development of vascular disease. Here, we review the cross talk among vessel wall stiffening, endothelial contractility, and vascular disease, which is controlled by Rho-driven actomyosin contractility and cellular mechanotransduction. In addition to discussing the various inputs and relevant molecular events in the endothelium, we address which actomyosin-regulated changes at cell adhesion complexes are genetically associated with human cardiovascular disease. Finally, we discuss recent findings that broaden therapeutic options for targeting this important mechanical signaling pathway in vascular pathogenesis. vascular stiffening) and the various external cues that regulate this. In addition, we will discuss the relationship between endothelial contractility and leukocyte extravasation and finally address (future) possibilities to therapeutically target ECs to reduce chronic, stiffness-related, vascular inflammation.
Systemic Regulation of Vascular StiffnessArterial stiffness is strongly associated with high blood pressure, as well as with aging, and serves as an independent predictor of human cardiovascular disease. An elevation in arterial stiffness increases systolic blood pressure, thereby promoting cardiac hypertrophy, and decreases the diastolic blood pressure which is a trigger for developing myocardial ischemia. 7 Aortic stiffness also affects the microcirculation and vice versa, microcirculatory changes affect aortic stiffness. Stiffening of the aortic wall leads to increased pulse wave velocity (PWV) and premature reflected waves with elevated systolic and pulsatile central hemodynamic load resulting in microcirculatory damages in peripheral tissues. Conversely, microvasculature remodeling elevates systemic vascular resistance and pulse wave reflection, which stiffens the aortic wall, indicating that the endothelium has both a responsive and a causal role in vascular stiffening. 7 Increased PWV accurately estimates arterial wall stiffness and has recently been included in official hypertension guidelines. PWV values increase with age, and increases in aortic PWV is a g...