title: Notch signaling mediates crosstalk between endothelial cells and macrophages via Dll4 and IL6 in cardiac microvascular inflammation.
abstract: Although short-term outcomes have improved with modern era immunosuppression, little progress has been made in long-term graft survival in cardiac transplantation. Antibody-mediated rejection (AMR) is one of the leading causes of graft failure and contributes significantly to poor long-term outcomes. Endothelial cell (EC) injury, intravascular macrophage infiltrate and microvascular inflammation are the histological features of AMR. Nevertheless, mechanisms of AMR remain unclear and treatment is still limited. Here, we investigated the mechanisms underlying vascular and inflammatory cell network involved in AMR at endothelial and macrophage levels, using endomyocardial transplant biopsies and EC/monocyte cocultures. First, we found that AMR associates with changes in Notch signaling at endothelium/monocyte interface including loss of endothelial Notch4 and the acquisition of the Notch ligand Dll4 in both cell types. We showed that endothelial Dll4 induces macrophage polarization into a pro-inflammatory fate (CD40(high)CD64(high)CD200R(low) HLA-DR(low)CD11b(low)) eliciting the production of IL-6. Dll4 and IL-6 are both Notch-dependent and are required for macrophage polarization through selective down and upregulation of M2- and M1-type markers, respectively. Overall, these findings highlight the impact of the graft's endothelium on macrophage recruitment and differentiation upon AMR via Notch signaling. We identified Dll4 and IL-6 as coregulators of vascular inflammation in cardiac transplantation and as potential targets for immunotherapy.
authors.affiliation: INSERM UMR1064, Centre de Recherche en Transplantation et Immunologie, LabEx IGO and LabEx Transplantex, Nantes F44000, France; CHU de Nantes, Institut de Transplantation-Urologie-Néphrologie, ITUN, Nantes F44000, France; LUNAM Université de Nantes, Faculté de Médecine, Nantes F44000, France.
authors.forename: Angélique
authors.initials: A
authors.lastname: Pabois
authors.affiliation: INSERM UMR1064, Centre de Recherche en Transplantation et Immunologie, LabEx IGO and LabEx Transplantex, Nantes F44000, France; CHU de Nantes, Institut de Transplantation-Urologie-Néphrologie, ITUN, Nantes F44000, France; LUNAM Université de Nantes, Faculté de Médecine, Nantes F44000, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Pagie
authors.affiliation: INSERM UMR1064, Centre de Recherche en Transplantation et Immunologie, LabEx IGO and LabEx Transplantex, Nantes F44000, France; CHU de Nantes, Institut de Transplantation-Urologie-Néphrologie, ITUN, Nantes F44000, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Gérard
authors.affiliation: Service d'Anatomie Pathologique, CHU de Nantes, Nantes F44000, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Laboisse
authors.affiliation: Service de transplantation cardiaque, CHU de Nantes, Nantes F44000, France.
authors.forename: Sabine
authors.initials: S
authors.lastname: Pattier
authors.affiliation: LUNAM Université de Nantes, Faculté de Médecine, Nantes F44000, France; Plateforme MicroPICell SFR Santé - IRT, Nantes, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Hulin
authors.affiliation: LUNAM Université de Nantes, Faculté de Médecine, Nantes F44000, France; Plateforme MicroPICell SFR Santé - IRT, Nantes, France.
authors.forename: Steven
authors.initials: S
authors.lastname: Nedellec
authors.affiliation: Service d'Anatomie Pathologique, CHU de Nantes, Nantes F44000, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Toquet
authors.affiliation: INSERM UMR1064, Centre de Recherche en Transplantation et Immunologie, LabEx IGO and LabEx Transplantex, Nantes F44000, France; CHU de Nantes, Institut de Transplantation-Urologie-Néphrologie, ITUN, Nantes F44000, France; LUNAM Université de Nantes, Faculté de Médecine, Nantes F44000, France. Electronic address: Beatrice.Charreau@univ-nantes.fr.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Charreau
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D064591:Allografts / Q000098:blood supply / Q000276:immunology; D002135:Calcium-Binding Proteins; D002450:Cell Communication / Q000276:immunology; D018920:Coculture Techniques; D042783:Endothelial Cells / Q000276:immunology* / Q000378:metabolism; D006084:Graft Rejection / Q000276:immunology* / Q000378:metabolism; D057809:HEK293 Cells; D016027:Heart Transplantation; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D055806:Microvessels / Q000276:immunology* / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; C424126:DLL4 protein, human; C508600:IL6 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6; D051880:Receptors, Notch
keywords: Cardiac transplant; Endothelial cells; Macrophage polarization; Notch signaling