title: Acute hemolytic vascular inflammatory processes are prevented by nitric oxide replacement or a single dose of hydroxyurea.
abstract: Hemolysis and consequent release of cell-free hemoglobin (CFHb) impair vascular nitric oxide (NO) bioavailability and cause oxidative and inflammatory processes. Hydroxyurea (HU), a common therapy for sickle cell disease (SCD), induces fetal Hb production and can act as an NO donor. We evaluated the acute inflammatory effects of intravenous water-induced hemolysis in C57BL/6 mice and determined the abilities of an NO donor, diethylamine NONOate (DEANO), and a single dose of HU to modulate this inflammation. Intravenous water induced acute hemolysis in C57BL/6 mice, attaining plasma Hb levels comparable to those observed in chimeric SCD mice. This hemolysis resulted in significant and rapid systemic inflammation and vascular leukocyte recruitment within 15 minutes, accompanied by NO metabolite generation. Administration of another potent NO scavenger (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) to C57BL/6 mice induced similar alterations in leukocyte recruitment, whereas hemin-induced inflammation occurred over a longer time frame. Importantly, the acute inflammatory effects of water-induced hemolysis were abolished by the simultaneous administration of DEANO or HU, without altering CFHb, in an NO pathway-mediated manner. In vitro, HU partially reversed the Hb-mediated induction of endothelial proinflammatory cytokine secretion and adhesion molecule expression. In summary, pathophysiological levels of hemolysis trigger an immediate inflammatory response, possibly mediated by vascular NO consumption. HU presents beneficial anti-inflammatory effects by inhibiting rapid-onset hemolytic inflammation via an NO-dependent mechanism, independently of fetal Hb elevation. Data provide novel insights into mechanisms of hemolytic inflammation and further support perspectives for the use of HU as an acute treatment for SCD and other hemolytic disorders.
authors.affiliation: Hematology Center, University of Campinas (UNICAMP), Campinas, Brazil; Instituto Israelita de Ensino e Pesquisa Albert Einstein, Hospital Israelita Albert Einstein, São Paulo, Brazil;
authors.forename: Camila Bononi
authors.initials: CB
authors.lastname: Almeida
authors.affiliation: Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil;
authors.forename: Lucas Eduardo Botelho
authors.identifier: http://orcid.org/0000-0003-4254-7509
authors.initials: LE
authors.lastname: Souza
authors.affiliation: Hematology Center, University of Campinas (UNICAMP), Campinas, Brazil;
authors.forename: Flavia Costa
authors.initials: FC
authors.lastname: Leonardo
authors.affiliation: Department of Genetics, Evolution and Bioagents, and.
authors.forename: Fabio Trindade Maranhão
authors.initials: FT
authors.lastname: Costa
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, UNICAMP, Campinas, Brazil.
authors.forename: Claudio C
authors.identifier: http://orcid.org/0000-0002-9413-0572
authors.initials: CC
authors.lastname: Werneck
authors.affiliation: Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil;
authors.forename: Dimas Tadeu
authors.initials: DT
authors.lastname: Covas
authors.affiliation: Hematology Center, University of Campinas (UNICAMP), Campinas, Brazil;
authors.forename: Fernando Ferreira
authors.initials: FF
authors.lastname: Costa
authors.affiliation: Hematology Center, University of Campinas (UNICAMP), Campinas, Brazil;
authors.forename: Nicola
authors.identifier: http://orcid.org/0000-0001-5726-7919
authors.initials: N
authors.lastname: Conran
mesh_terms: D000755:Anemia, Sickle Cell / Q000097:blood / Q000188:drug therapy / Q000473:pathology; D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D003497:Cyclic N-Oxides / Q000494:pharmacology*; D004195:Disease Models, Animal; D016166:Free Radical Scavengers / Q000494:pharmacology*; D006454:Hemoglobins / Q000378:metabolism*; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D006834:Hydrazines / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006918:Hydroxyurea / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology*; D007249:Inflammation / Q000097:blood / Q000188:drug therapy / Q000473:pathology; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000037:antagonists & inhibitors / Q000494:pharmacology; D061251:Primary Cell Culture; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014783:Viscosity; D014867:Water / Q000494:pharmacology
chemical_list: D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D006454:Hemoglobins; D006834:Hydrazines; D007093:Imidazoles; D020030:Nitric Oxide Donors; D014409:Tumor Necrosis Factor-alpha; D014867:Water; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; D009569:Nitric Oxide; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; D006918:Hydroxyurea