Background: Severe hemolytic disease of the newborn leads to the release of pro-oxidative free heme (FH). Heme oxygenase (HO) is primarily responsible for detoxifying FH. Objective: To investigate the protective effects of HO in a model of heme overload. Methods: For in vitro studies, NIH3T3 HO-1-luc cells were incubated with 10, 30, or 60 µM FH or methemalbumin (MHA). HO-1 promoter activity was assessed 3, 6, and 24 h after treatment. Cell survival was indexed by viability assays. For in vivo studies, 1- and 5-week-old wild-type (Wt) or HO-1-heterozygous (Het, HO-1+/-) mice were given 60 µmol FH or MHA/kg intraperitoneally. After 24 h, plasma aspartate aminotransferease (AST)/alanine transaminase (ALT) and hemopexin, liver HO activity, and lipid peroxidation (LP) were determined. Results: In HO-1-luc cells, HO-1 promoter activity peaked 6 h after incubation with 30 µM FH (1.6-fold) or 60 µM MHA (2.1-fold) over baseline. Twenty-four hours after exposure to 60 µM FH, a decrease in viability of 80% was found, compared with no decrease after exposure to 60 µM MHA. In 1-week-old Wt and HO-1 Het pups given 60 µmol FH/kg, HO activity significantly increased 3.5- and 3.1-fold, respectively. No changes in LP or AST/ALT levels were observed. In adult Wt and HO-1 Het mice, HO activity increased (3.0- and 2.6-fold, respectively). LP and AST levels significantly increased 28.4- and 2.7-fold, respectively, in adult HO-1 Het mice. Hemopexin levels at baseline were higher in adults compared with newborns for both Wt and Het mice. In addition, FH induced hemopexin levels in both adults and newborns, but to a lesser degree in newborns. Conclusions: FH is highly toxic in vitro, but its toxicity is abolished when bound to albumin. Newborns appear to be protected from the pro-oxidative effects of FH, which may be mediated by heme binding and a higher absolute HO activity at baseline and after FH-mediated induction.

Larsen R, Gozzelino R, Jeney V, Tokaji L, Bozza FA, Japiassu AM, Bonaparte D, Cavalcante MM, Chora A, Ferreira A, Marguti I, Cardoso S, Sepulveda N, Smith A, Soares MP: A central role for free heme in the pathogenesis of severe sepsis. Sci Transl Med 2010;2:51ra71.
Eskew JD, Vanacore RM, Sung L, Morales PJ, Smith A: Cellular protection mechanisms against extracellular heme: heme-hemopexin, but not free heme, activates the n-terminal c-jun kinase. J Biol Chem 1999;274:638-648.
Dutra FF, Bozza MT: Heme on innate immunity and inflammation. Front Pharmacol 2014;5:115.
Kovtunovych G, Eckhaus MA, Ghosh MC, Ollivierre-Wilson H, Rouault TA: Dysfunction of the heme recycling system in heme oxygenase 1-deficient mice: effects on macrophage viability and tissue iron distribution. Blood 2010;116:6054-6062.
Melamed-Frank M, Lache O, Enav BI, Szafranek T, Levy NS, Ricklis RM, Levy AP: Structure-function analysis of the antioxidant properties of haptoglobin. Blood 2001;98:3693-3698.
Tolosano E, Fagoonee S, Morello N, Vinchi F, Fiorito V: Heme scavenging and the other facets of hemopexin. Antioxid Redox Signal 2010;12:305-320.
Maines MD, Kappas A: Metals as regulators of heme metabolism. Science 1977;198:1215-1221.
Tenhunen R, Marver HS, Schmid R: The enzymatic conversion of heme to bilirubin by microsomal heme oxygenase. Proc Natl Acad Sci USA 1968;61:748-755.
Vinchi F, Gastaldi S, Silengo L, Altruda F, Tolosano E: Hemopexin prevents endothelial damage and liver congestion in a mouse model of heme overload. Am J Pathol 2008;173:289-299.
He CX, Campbell CM, Zhao H, Kalish FS, Schulz S, Vreman HJ, Wong RJ, Stevenson DK: Effects of zinc deuteroporphyrin bis glycol on newborn mice after heme loading. Pediatr Res 2011;70:467-472.
Morioka I, Wong RJ, Abate A, Vreman HJ, Contag CH, Stevenson DK: Systemic effects of orally-administered zinc and tin (iv) metalloporphyrins on heme oxygenase expression in mice. Pediatr Res 2006;59:667-672.
Vreman HJ, Stevenson DK: Heme oxygenase activity as measured by carbon monoxide production. Anal Biochem 1988;168:31-38.
Wong RJ, Vreman HJ, Schulz S, Kalish FS, Pierce NW, Stevenson DK: In vitro inhibition of heme oxygenase isoenzymes by metalloporphyrins. J Perinatol 2011;31(suppl 1):S35-S41.
Abate A, Zhao H, Wong RJ, Stevenson DK: The role of bach1 in the induction of heme oxygenase by tin mesoporphyrin. Biochem Biophys Res Commun 2007;354:757-763.
Zhang W, Contag PR, Hardy J, Zhao H, Vreman HJ, Hajdena-Dawson M, Wong RJ, Stevenson DK, Contag CH: Selection of potential therapeutics based on in vivo spatiotemporal transcription patterns of heme oxygenase-1. J Mol Med 2002;80:655-664.
Zhao H, Wong RJ, Kalish FS, Nayak NR, Stevenson DK: Effect of heme oxygenase-1 deficiency on placental development. Placenta 2009;30:861-868.
Schulz S, Chisholm KM, Zhao H, Kalish F, Yang Y, Wong RJ, Stevenson DK: Heme oxygenase-1 confers protection and alters t-cell populations in a mouse model of neonatal intestinal inflammation. Pediatr Res 2015;77:640-648.
Vreman HJ, Wong RJ, Sanesi CA, Dennery PA, Stevenson DK: Simultaneous production of carbon monoxide and thiobarbituric acid reactive substances in rat tissue preparations by an iron-ascorbate system. Can J Physiol Pharmacol 1998;76:1057-1065.
Paoli M, Anderson BF, Baker HM, Morgan WT, Smith A, Baker EN: Crystal structure of hemopexin reveals a novel high-affinity heme site formed between two beta-propeller domains. Nat Struct Biol 1999;6:926-931.
Fujioka K, Kalish F, Zhao H, Lu S, Wong S, Wong RJ, Stevenson DK: Induction of heme oxygenase-1 attenuates the severity of sepsis in a non-surgical preterm mouse model. Shock 2017;47:242-250.
Schulz S, Wong RJ, Jang KY, Kalish F, Chisholm KM, Zhao H, Vreman HJ, Sylvester KG, Stevenson DK: Heme oxygenase-1 deficiency promotes the development of necrotizing enterocolitis-like intestinal injury in a newborn mouse model. Am J Physiol Gastrointest Liver Physiol 2013;304: G991-G1001.
Ozsurekci Y, Aykac K: Oxidative stress related diseases in newborns. Oxid Med Cell Longev 2016;2016:2768365.
Jirtle RL, Skinner MK: Environmental epigenomics and disease susceptibility. Nat Rev Genet 2007;8:253-262.
Perera F, Herbstman J: Prenatal environmental exposures, epigenetics, and disease. Reprod Toxicol 2011;31:363-373.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.