The Pathogenesis and Impact of Arterial Stiffening in Hypertension The 2023 John H. Laragh Research Award.

Fifty years ago, Dr. John Laragh brought forward the "vasoconstriction-volume hypothesis" of hypertension. This is Ohm's Law in blood pressure regulation, explicating hypertension as a consequence of increased peripheral vascular resistance, cardiac output, or both. Resistance vessels, those of a diameter less than 200 μm, determines mean arterial pressure by controlling peripheral vascular resistance. In comparison, large capacitance arteries, particularly the aorta, confines the systolic and diastolic blood pressure in physiological range through the "windkessel effect". Loss of this cushioning function results in aortic stiffening and isolated systolic hypertension, both of which are independently associated with increased risk for coronary, cerebral, and renal diseases. Aortic stiffening is both a cause and a consequence of hypertension. On one hand, aortic stiffness precedes the onset of hypertension in populations and experimental models, and hemodynamic derangements related to aortic stiffening contributes to the development of hypertension by promoting renal dysfunction. On the other hand, the vasculature itself is a hypertensive target organ and hypertensive mechanical stretch directly induces the pathogenesis of aortic adventitial remodeling. Various cell types, including bone marrow derived circulating fibrocytes, vascular stem cell antigen 1 positive progenitors, and endothelial to mesenchymal transition, and to a lesser extent resident fibroblasts, contribute to adventitial matrix deposition and aortic stiffening in hypertension. Vascular smooth muscle stiffness is another important contributor of aortic stiffening. Understanding the roles of immune components and specific signal pathways in the pathogenesis aortic stiffening paves the path to novel antihypertensive and anti-fibrosis therapies.