Hemopexin Therapy Improves Cardiovascular Function by Preventing Heme-Induced Endothelial Toxicity in Mouse Models of Hemolytic Diseases
Francesca Vinchi; Lucia De Franceschi; Alessandra Ghigo; Tim Townes; James Cimino; Lorenzo Silengo; Emilio Hirsch; Fiorella Altruda; Emanuela Tolosano
CIRCULATIONAHA.112.130179
Published online before print February 27, 2013,

Abstract

Background—Hemolytic diseases are characterized by enhanced intravascular hemolysis resulting in heme-catalyzed reactive oxygen species (ROS) generation, that leads to endothelial dysfunction and oxidative damage. Hemopexin (Hx) is a plasma heme scavenger able to prevent endothelial damage and tissue congestion in a model of heme overload. Here, we tested whether Hx could be used as a therapeutical tool to counteract heme toxic effects on the cardiovascular system in hemolytic diseases.

Methods and Results—By using a model of heme overload in Hx-null mice, we demonstrated that heme excess in plasma, if not bound to Hx, promoted the production of ROS and the induction of adhesion molecules and caused the reduction of nitric oxide (NO) availability. Then, we used β-thalassemia and Sickle Cell Disease (SCD) mice as models of hemolytic diseases to evaluate the efficacy of a Hx-based therapy in the treatment of vascular dysfunction related to heme overload. Our data demonstrated that Hx (i)prevented heme-iron loading in the cardiovascular system, thus limiting the production of ROS as well as the induction of adhesion molecules and the oxidative inactivation of NOS/NO, and (ii)promoted heme recovery and detoxification by the liver mainly through the induction of Heme Oxygenase (HO) activity. Moreover, we showed that in SCD mice, endothelial activation and oxidation were associated with increased blood pressure and altered cardiac function and the administration of exogenous Hx was found to almost completely normalize these parameters.

Conclusions—Hemopexin treatment is a promising novel therapy to protect against heme-induced cardiovascular dysfunction in hemolytic disorders.