title: Hemopexin counteracts systolic dysfunction induced by heme-driven oxidative stress.
abstract: Heart failure is a leading cause of morbidity and mortality in patients affected by different disorders associated to intravascular hemolysis. The leading factor is the presence of pathologic amount of pro-oxidant free heme in the bloodstream, due to the exhaustion of the natural heme scavenger Hemopexin (Hx). Here, we evaluated whether free heme directly affects cardiac function, and tested the therapeutic potential of replenishing serum Hx for increasing serum heme buffering capacity. The effect of heme on cardiac function was assessed in vitro, on primary cardiomyocytes and H9c2 myoblast cell line, and in vivo, in Hx-/-mice and in genetic and acquired mouse models of intravascular hemolysis. Purified Hx or anti-oxidants N-Acetyl-L-cysteine and α-tocopherol were used to counteract heme cardiotoxicity. In mice, Hx loss/depletion resulted in heme accumulation and enhanced reactive oxygen species (ROS) production in the heart, which ultimately led to severe systolic dysfunction. Similarly, high ROS reduced systolic Ca2+transient amplitudes and fractional shortening in primary cardiomyocytes exposed to free heme. In keeping with these Ca2+handling alterations, oxidation and CaMKII-dependent phosphorylation of Ryanodine Receptor 2 were higher in Hx-/-hearts than in controls. Administration of anti-oxidants prevented systolic failure both in vitro and in vivo. Intriguingly, Hx rescued contraction defects of heme-treated cardiomyocytes and preserved cardiac function in hemolytic mice. We show that heme-mediated oxidative stress perturbs cardiac Ca2+homeostasis and promotes contractile dysfunction. Scavenging heme, Hx counteracts cardiac heme toxicity and preserves left ventricular function. Our data generate the rationale to consider the therapeutic use of Hx to limit the cardiotoxicity of free heme in hemolytic disorders.
authors.affiliation: Dept. Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.
authors.forename: Giada
authors.initials: G
authors.lastname: Ingoglia
authors.affiliation: Dept. Internal Medicine II, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Can Martin
authors.initials: CM
authors.lastname: Sag
authors.affiliation: Dept. Internal Medicine II, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Nikolai
authors.initials: N
authors.lastname: Rex
authors.affiliation: Dept. Medicine, Università degli Studi di Verona-Azienda Ospedaliera Universitaria Integrata Verona, Verona, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: De Franceschi
authors.affiliation: Heidelberg University Hospital / EMBL Heidelberg, Heidelberg, Germany.
authors.forename: Francesca
authors.initials: F
authors.lastname: Vinchi
authors.affiliation: Dept. Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.
authors.forename: James
authors.initials: J
authors.lastname: Cimino
authors.affiliation: Dept. Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Petrillo
authors.affiliation: Dept. Internal Medicine II, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wagner
authors.affiliation: Dept. Internal Medicine II, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kreitmeier
authors.affiliation: Dept. Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Silengo
authors.affiliation: Dept. Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.
authors.forename: Fiorella
authors.initials: F
authors.lastname: Altruda
authors.affiliation: Dept. Internal Medicine II, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Lars S
authors.initials: LS
authors.lastname: Maier
authors.affiliation: Dept. Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.
authors.forename: Emilio
authors.initials: E
authors.lastname: Hirsch
authors.affiliation: Dept. Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Ghigo
authors.affiliation: Dept. Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy. Electronic address: emanuela.tolosano@unito.it.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Tolosano
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D002460:Cell Line; D054143:Heart Failure, Systolic / Q000188:drug therapy* / Q000503:physiopathology; D006454:Hemoglobins / Q000235:genetics / Q000378:metabolism*; D006461:Hemolysis; D006466:Hemopexin / Q000235:genetics / Q000627:therapeutic use*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D010085:Oxidative Phosphorylation; D018384:Oxidative Stress; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D017086:beta-Thalassemia / Q000188:drug therapy* / Q000503:physiopathology
chemical_list: D006454:Hemoglobins; D017382:Reactive Oxygen Species; D019837:Ryanodine Receptor Calcium Release Channel; D006466:Hemopexin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002118:Calcium
keywords: Heart; Heme; Hemopexin; ROS; Systolic function