title: Excess of heme induces tissue factor-dependent activation of coagulation in mice.
abstract: An excess of free heme is present in the blood during many types of hemolytic anemia. This has been linked to organ damage caused by heme-mediated oxidative stress and vascular inflammation. We investigated the mechanism of heme-induced coagulation activation in vivo. Heme caused coagulation activation in wild-type mice that was attenuated by an anti-tissue factor antibody and in mice expressing low levels of tissue factor. In contrast, neither factor XI deletion nor inhibition of factor XIIa-mediated factor XI activation reduced heme-induced coagulation activation, suggesting that the intrinsic coagulation pathway is not involved. We investigated the source of tissue factor in heme-induced coagulation activation. Heme increased the procoagulant activity of mouse macrophages and human PBMCs. Tissue factor-positive staining was observed on leukocytes isolated from the blood of heme-treated mice but not on endothelial cells in the lungs. Furthermore, heme increased vascular permeability in the mouse lungs, kidney and heart. Deletion of tissue factor from either myeloid cells, hematopoietic or endothelial cells, or inhibition of tissue factor expressed by non-hematopoietic cells did not reduce heme-induced coagulation activation. However, heme-induced activation of coagulation was abolished when both non-hematopoietic and hematopoietic cell tissue factor was inhibited. Finally, we demonstrated that coagulation activation was partially attenuated in sickle cell mice treated with recombinant hemopexin to neutralize free heme. Our results indicate that heme promotes tissue factor-dependent coagulation activation and induces tissue factor expression on leukocytes in vivo. We also demonstrated that free heme may contribute to thrombin generation in a mouse model of sickle cell disease.
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Erica M
authors.initials: EM
authors.lastname: Sparkenbaugh
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Department of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Pichika
authors.initials: P
authors.lastname: Chantrathammachart
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Shaobin
authors.initials: S
authors.lastname: Wang
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Will
authors.initials: W
authors.lastname: Jonas
authors.affiliation: Department of Early Discovery Biochemistry, Genentech Inc., South San Francisco, CA, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kirchhofer
authors.affiliation: Department of Pathology, Vanderbilt University, Nashville, TN, USA.
authors.forename: David
authors.initials: D
authors.lastname: Gailani
authors.affiliation: Departments of Biomedical Engineering and Medicine, Oregon Health and Science University, Portland, OR, USA.
authors.forename: Andras
authors.initials: A
authors.lastname: Gruber
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Raj
authors.initials: R
authors.lastname: Kasthuri
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Nigel S
authors.initials: NS
authors.lastname: Key
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Nigel
authors.initials: N
authors.lastname: Mackman
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA rafal_pawlinski@med.unc.edu.
authors.forename: Rafal
authors.initials: R
authors.lastname: Pawlinski
mesh_terms: D000743:Anemia, Hemolytic / Q000097:blood / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D000755:Anemia, Sickle Cell / Q000097:blood / Q000235:genetics* / Q000473:pathology; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects* / Q000235:genetics; D002199:Capillary Permeability / Q000187:drug effects; D002478:Cells, Cultured; D005172:Factor XI / Q000235:genetics / Q000378:metabolism; D015956:Factor XIIa / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D005260:Female; D017353:Gene Deletion; D015870:Gene Expression; D006418:Heme / Q000008:administration & dosage*; D006466:Hemopexin / Q000494:pharmacology; D006801:Humans; D007275:Injections, Intravenous; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D013552:Swine; D013925:Thromboplastin / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000906:Antibodies; D034741:RNA, Small Interfering; D006418:Heme; D005172:Factor XI; D006466:Hemopexin; D013925:Thromboplastin; D015956:Factor XIIa