title: Junín virus infection of human hematopoietic progenitors impairs in vitro proplatelet formation and platelet release via a bystander effect involving type I IFN signaling.
abstract: Argentine hemorrhagic fever (AHF) is an endemo-epidemic disease caused by Junín virus (JUNV), a member of the arenaviridae family. Although a recently introduced live attenuated vaccine has proven to be effective, AHF remains a potentially lethal infection. Like in other viral hemorrhagic fevers (VHF), AHF patients present with fever and hemorrhagic complications. Although the causes of the bleeding are poorly understood, impaired hemostasis, endothelial cell dysfunction and low platelet counts have been described. Thrombocytopenia is a common feature in VHF syndromes, and it is a major sign for its diagnosis. However, the underlying pathogenic mechanism has not yet been elucidated. We hypothesized that thrombocytopenia results from a viral-triggered alteration of the megakaryo/thrombopoiesis process. Therefore, we evaluated the impact of JUNV on megakaryopoiesis using an in vitro model of human CD34+ cells stimulated with thrombopoietin. Our results showed that CD34+ cells are infected with JUNV in a restricted fashion. Infection was transferrin receptor 1 (TfR1)-dependent and the surface expression of TfR1 was higher in infected cultures, suggesting a novel arenaviral dissemination strategy in hematopoietic progenitor cells. Although proliferation, survival, and commitment in JUNV-infected cultures were normal, viral infection impaired thrombopoiesis by decreasing in vitro proplatelet formation, platelet release, and P-selectin externalization via a bystander effect. The decrease in platelet release was also TfR1-dependent, mimicked by poly(I:C), and type I interferon (IFN alpha/beta) was implicated as a key paracrine mediator. Among the relevant molecules studied, only the transcription factor NF-E2 showed a moderate decrease in expression in megakaryocytes from either infected cultures or after type I IFN treatment. Moreover, type I IFN-treated megakaryocytes presented ultrastructural abnormalities resembling the reported thrombocytopenic NF-E2(-/-) mouse phenotype. Our study introduces a potential mechanism for thrombocytopenia in VHF and other diseases associated with increased bone marrow type I IFN levels.
authors.affiliation: Department of Thrombosis and Hemostasis, Hematological Research Institute "Mariano R Castex", National Academy of Medicine, CONICET, Buenos Aires, Argentina.
authors.forename: Roberto G
authors.initials: RG
authors.lastname: Pozner
authors.forename: Agustín E
authors.initials: AE
authors.lastname: Ure
authors.forename: Carolina
authors.initials: C
authors.lastname: Jaquenod de Giusti
authors.forename: Lina P
authors.initials: LP
authors.lastname: D'Atri
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Italiano
authors.forename: Oscar
authors.initials: O
authors.lastname: Torres
authors.forename: Victor
authors.initials: V
authors.lastname: Romanowski
authors.forename: Mirta
authors.initials: M
authors.lastname: Schattner
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Gómez
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D018952:Antigens, CD34 / Q000378:metabolism; D001117:Arenaviridae Infections / Q000378:metabolism*; D001792:Blood Platelets / Q000166:cytology / Q000378:metabolism*; D024201:Bystander Effect / Q000502:physiology; D002469:Cell Separation; D005312:Fetal Blood; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism* / Q000821:virology*; D006801:Humans; D007370:Interferon Type I / Q000378:metabolism*; D018051:Junin virus; D046529:Microscopy, Electron, Transmission; D050984:NF-E2 Transcription Factor, p45 Subunit / Q000378:metabolism; D011990:Receptors, Transferrin / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D034061:Thrombopoiesis / Q000502:physiology*
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; C068126:CD71 antigen; D007370:Interferon Type I; D050984:NF-E2 Transcription Factor, p45 Subunit; C494692:NFE2 protein, human; D011990:Receptors, Transferrin