title: Loss of DGKε induces endothelial cell activation and death independently of complement activation.
abstract: Atypical hemolytic uremic syndrome (aHUS) is classically described to result from a dysregulation of the complement alternative pathway, leading to glomerular endothelial cell (EC) damage and thrombosis. However, recent findings in families with aHUS of mutations in the DGKE gene, which is not an integral component of the complement cascade, led us to consider other pathophysiologic mechanisms for this disease. Here, we demonstrate that loss of DGKε expression/activity in EC induces an increase in ICAM-1 and tissue factor expression through the upregulation of p38-MAPK-mediated signals, thus highlighting a proinflammatory and prothrombotic phenotype of DGKε-deficient ECs. More interestingly, DGKE silencing also increases EC apoptosis and impairs EC migration and angiogenesis in vitro, suggesting that DGKE loss-of-function mutations impair EC repair and angiogenesis in vivo. Conversely, DGKE knockdown moderately decreases the expression of the complement inhibitory protein MCP on quiescent EC, but does not induce complement deposition on their surface in vitro. Collectively, our data strongly suggest that in DGKE-associated aHUS patients, thrombotic microangiopathy results from impaired EC proliferation and angiogenesis rather than complement-mediated EC lesions. Our study expands the current knowledge of aHUS mechanisms and has implications for the treatment of patients with isolated DGKE mutations.
authors.affiliation: INSERM Unité Mixte de Recherche S-1064, Institut de Transplantation Urologie-Nephrologie, Centre Hospitalier Universitaire de Nantes, University of Nantes, Nantes, France;
authors.forename: Sarah
authors.initials: S
authors.lastname: Bruneau
authors.affiliation: INSERM Unité Mixte de Recherche S-1064, Institut de Transplantation Urologie-Nephrologie, Centre Hospitalier Universitaire de Nantes, University of Nantes, Nantes, France;
authors.forename: Mélanie
authors.initials: M
authors.lastname: Néel
authors.affiliation: INSERM Unité Mixte de Recherche S-1138, Cordeliers Research Center, Complement and Diseases Team, Paris, France; Université Paris Descartes Sorbonne Paris-Cité, Paris, France; Université Pierre et Marie Curie (Paris-6), Paris, France;
authors.forename: Lubka T
authors.initials: LT
authors.lastname: Roumenina
authors.affiliation: INSERM Unité Mixte de Recherche S-1138, Cordeliers Research Center, Complement and Diseases Team, Paris, France; Service de Néphrologie, Hôpital Claude Huriez, Centre Hospitalier Universitaire de Lille, France; and.
authors.forename: Marie
authors.initials: M
authors.lastname: Frimat
authors.affiliation: INSERM Unité Mixte de Recherche S-1064, Institut de Transplantation Urologie-Nephrologie, Centre Hospitalier Universitaire de Nantes, University of Nantes, Nantes, France;
authors.forename: Lætitia
authors.initials: L
authors.lastname: Laurent
authors.affiliation: INSERM Unité Mixte de Recherche S-1138, Cordeliers Research Center, Complement and Diseases Team, Paris, France; Assistance Publique-Hôpitaux de Paris, Service d'Immunologie Biologique, Hôpital Européen Georges Pompidou, Paris, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Frémeaux-Bacchi
authors.affiliation: INSERM Unité Mixte de Recherche S-1064, Institut de Transplantation Urologie-Nephrologie, Centre Hospitalier Universitaire de Nantes, University of Nantes, Nantes, France;
authors.forename: Fadi
authors.initials: F
authors.lastname: Fakhouri
mesh_terms: D016923:Cell Death; D002465:Cell Movement; D003167:Complement Activation; D003176:Complement C3 / Q000276:immunology; D019852:Diacylglycerol Kinase / Q000235:genetics* / Q000276:immunology; D019040:E-Selectin / Q000235:genetics; D042783:Endothelial Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D005786:Gene Expression Regulation; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics; D020935:MAP Kinase Signaling System; D018919:Neovascularization, Physiologic; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D003176:Complement C3; D019040:E-Selectin; D034741:RNA, Small Interfering; D018799:Intercellular Adhesion Molecule-1; C526464:DGKE protein, human; D019852:Diacylglycerol Kinase