title: Hemoglobin-induced endothelial cell permeability is controlled, in part, via a myeloid differentiation primary response gene-88-dependent signaling mechanism.
abstract: The release of hemoglobin (Hb) with hemolysis causes vascular dysfunction. New evidence implicates Hb-induced NF-κB and hypoxia inducible factor (HIF) activation, which may be under the control of a Toll-like receptor (TLR)-signaling pathway. Nearly all TLR-signaling pathways activate the myeloid differentiation primary response gene-88 (MyD88) that regulates NF-κB. We hypothesized that the differing transition states of Hb influence endothelial cell permeability via NF-κB activation and HIF regulation through a MyD88-dependent pathway. In cultured human dermal microvascular endothelial cells (HMECs-1), we examined the effects of Hb in the ferrous (HbFe(2+)), ferric (HbFe(3+)), and ferryl (HbFe(4+)) transition states on NF-κB and HIF activity, HIF-1α and HIF-2α mRNA up-regulation, and monolayer permeability, in the presence or absence of TLR4, MyD88, NF-κB, or HIF inhibition, as well as superoxide dismutase (SOD) and catalase. Our data showed that cell-free Hb, in each transition state, induced NF-κB and HIF activity, up-regulated HIF-1α and HIF-2α mRNA, and increased HMEC-1 permeability. The blockade of either MyD88 or NF-κB, but not TLR4, attenuated Hb-induced HIF activity, the up-regulation HIF-1 and HIF-2α mRNA, and HMEC-1 permeability. The inhibition of HIF activity exerted less of an effect on Hb-induced monolayer permeability. Moreover, SOD and catalase attenuated NF-κB, HIF activity, and monolayer permeability. Our results demonstrate that Hb-induced NF-κB and HIF are regulated by two mechanisms, either MyD88 activation or Hb transition state-induced ROS formation, that influence HMEC-1 permeability.
authors.affiliation: 1 Cardiovascular Pulmonary Research Group, Division of Cardiology, Department of Medicine.
authors.forename: Christina
authors.initials: C
authors.lastname: Lisk
authors.forename: Doug
authors.initials: D
authors.lastname: Kominsky
authors.forename: Stefan
authors.initials: S
authors.lastname: Ehrentraut
authors.forename: Joe
authors.initials: J
authors.lastname: Bonaventura
authors.forename: Rachelle
authors.initials: R
authors.lastname: Nuss
authors.forename: Kathryn
authors.initials: K
authors.lastname: Hassell
authors.forename: Eva
authors.initials: E
authors.lastname: Nozik-Grayck
authors.forename: David C
authors.initials: DC
authors.lastname: Irwin
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002463:Cell Membrane Permeability; D042783:Endothelial Cells / Q000378:metabolism*; D006454:Hemoglobins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D053594:Myeloid Differentiation Factor 88 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D010539:Permeability; D012333:RNA, Messenger / Q000235:genetics; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002374:Catalase; D006454:Hemoglobins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D012333:RNA, Messenger; D013482:Superoxide Dismutase; D051197:Toll-Like Receptor 4; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human; C507779:MYD88 protein, human; C495345:TLR4 protein, human