title: Therapeutic applications of bilirubin and biliverdin in transplantation.
abstract: Bilirubin is the end product of heme catabolism by heme oxygenases. The inducible form of these enzymes is heme oxygenase-1 (HO-1), which is the rate-limiting enzyme that can degrade heme into equimolar quantities of carbon monoxide (CO), biliverdin, and free iron. Biliverdin is very rapidly converted to bilirubin by the enzyme biliverdin reductase, and free iron upregulates the expression of ferritin. HO-1 is a ubiquitous stress protein and is induced in many cell types by various stimuli. Induced HO-1 exerts antiinflammatory effects and modulates apoptosis. Expression of HO-1 in vivo suppresses the inflammatory responses in endotoxic shock, hyperoxia, acute pleurisy, and organ transplantation, as well as ischemia-reperfusion injury, and thereby provides salutary effects in these conditions. Accumulating evidence indicates that biliverdin/bilirubin can mediate the protective effects of HO-1 in many disease models, such as IRI and organ transplantation, via its antiinflammatory, antiapoptotic, antiproliferative, and antioxidant properties, as well as its effects on the immune response. This review attempts to summarize these protective roles as well as the molecular mechanisms by which biliverdin/bilirubin benefit IRI and solid-organ transplantation, including chronic rejection, and islet transplantation.
authors.affiliation: Department of Surgery, Medical University Innsbruck, Innsbruck, Austria. robert.oellinger@i-med.ac.at
authors.forename: Robert
authors.initials: R
authors.lastname: Ollinger
authors.forename: Hongjun
authors.initials: H
authors.lastname: Wang
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Yamashita
authors.forename: Barbara
authors.initials: B
authors.lastname: Wegiel
authors.forename: Michael
authors.initials: M
authors.lastname: Thomas
authors.forename: Raimund
authors.initials: R
authors.lastname: Margreiter
authors.forename: Fritz H
authors.initials: FH
authors.lastname: Bach
mesh_terms: D000818:Animals; D001663:Bilirubin / Q000378:metabolism / Q000627:therapeutic use*; D001664:Biliverdine / Q000378:metabolism / Q000627:therapeutic use*; D019610:Cytoprotection; D006084:Graft Rejection / Q000201:enzymology / Q000235:genetics; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000378:metabolism / Q000502:physiology / Q000627:therapeutic use; D006801:Humans; D016381:Islets of Langerhans Transplantation; D008954:Models, Biological; D015394:Molecular Structure; D016377:Organ Transplantation / Q000502:physiology*; D015427:Reperfusion Injury / Q000188:drug therapy / Q000517:prevention & control; D014184:Transplantation, Homologous
chemical_list: D006418:Heme; D051547:Heme Oxygenase-1; D001664:Biliverdine; D001663:Bilirubin