To assess whether there might have been a link between the inflammatory phenotype and the development of PAH, we looked for correlations between typical PAH features, such as the PVR (obtained as the slope of multipoint mPpa/Q plots) or the pulmonary arteriolar remodeling and the pulmonary expressions of HO-1 and biological determinants implicated in inflammatory processes. This evidence concerns the gene HMOX1 and pulmonary arterial hypertension.