Pulmonary arterial hypertension is a complex pathology whose etiology is still not completely well clarified. The pathogenesis of pulmonary arterial hypertension involves different molecular mechanisms, with endothelial dysfunction playing a central role in disease progression. Both individual genetic predispositions and environmental factors seem to contribute to its onset. To further understand the complex relationship between endothelial and pulmonary hypertension and try to contribute to the development of future therapies, we report a comprehensive and updated review on endothelial function in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a rare condition characterized by high pulmonary artery pressure leading to right ventricular dysfunction and potential life-threatening consequences. It primarily affects the pre-capillary pulmonary vascular system. The exact pathophysiological mechanisms underlying PAH are not entirely known. Environmental factors; genetic predisposition; mitochondrial and microRNA dysfunction; and inflammatory, metabolic, and hormonal mechanisms may be involved. A central role is played by the dysfunction of the pulmonary vascular endothelium. This alteration is characterized by a reduction in vasodilatory and antiproliferative factors such as prostacyclin and nitric oxide and an increase in vasoconstrictive and mitogenic substances such as endothelin and thromboxane A2. Such imbalance leads to a progressive increase in pulmonary vascular resistance. The aim of the present review is to focus on the vascular endothelium and its role as a potential therapeutic target in PAH.

Systemic sclerosis (SSc) is a rare autoimmune connective tissue disease characterized by a widespread accumulation of extracellular matrix components leading to fibrosis of the skin and internal organs. Vascular changes occur in all involved tissues and are responsible for several distinctive clinical manifestations of the disease. This review focuses on the usefulness of various diagnostic tools in clinical practice for the early identification of clinical, functional, and/or structural RV impairment in SSc patients at risk of PH. It aims to identify specific causes of RV dysfunction, describe potential differences in outcome measures, and, ultimately, determine different cut-off values compared to subjects with PH not related to SSc.