[Hepatopulmonary syndrome: Prevalence, pathophysiology and clinical implications]

Hepatopulmonary syndrome (HPS) is a pulmonary vascular disease induced by portal hypertension that is characterized by dilation of the pulmonary capillaries and right-to-left shunting, leading to gas exchange abnormalities. While dysregulation of several endothelial cell (EC)-derived angiocrine factors and the development of HPS have been associated, the field is currently lacking in mechanistic understanding on how they contribute to disease initiation, perpetuation, and worsening. Although substantial progress has been made in the description of clinical characteristics and outcomes, no specific targeting therapy has been shown to have a long-term effect on the evolution of HPS; only liver transplantation can lead full or partial reversibility of the syndrome. This article aims to provide a comprehensive review of the clinical and epidemiological definitions of HPS and to describe its experimental models as well as recent advances in understanding the pathophysiology of the disease, with specific focus on BMP-9 and its signaling pathway.