P2X7R Signaling Controls Exosome Release by Macrophages and Donor MHC Cross-Dressing After Skin Transplantation
1Division of Plastic and Reconstructive Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 2Center for Transplantation Sciences, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA
Meeting: 2022 American Transplant Congress
Abstract number: 483
Keywords: Antigen presentation, Inflammation, Leukocytes, Skin transplantation
Topic: Basic Science » Basic Science » 03 - Antigen Presentation / Allorecognition / Dendritic Cells
Session Information
Session Name: Antigen Presentation and Costimulation
Session Type: Rapid Fire Oral Abstract
Date: Tuesday, June 7, 2022
Session Time: 3:30pm-5:00pm
Presentation Time: 3:50pm-4:00pm
Location: Hynes Room 309
*Purpose: Exosomes released by transplanted organs play an important role in the host’s immune response leading to their rejection. Donor exosomes contribute to alloimmunity by transferring donor MHC molecules on recipient APCs thus initiating activation of donor specific T cells in the recipient’s lymphoid organs and possibly in the graft. In this study, we investigated the role of innate immunity (ATP-mediated P2X7R signaling) in exosome release and MHC crossdressing in vitro and in skin-grafted mice.
*Methods: First, mouse macrophages were generated by culturing bone marrow cells with macrophage-colony stimulating factor for 7 days. The purity of bone marrow derived macrophages (BMDM) was > 98%. Next, BMDM were stimulated with lipopolysaccharide (LPS, 1 ug/mL) with or without a P2X7R inhibitor (A-438079) for 24h and 5mM of adenosine triphosphate (ATP) during the last 30 min of culture. The release of exosomes by activated macrophages was assessed by nanoparticle tracking analysis. In another set of experiments, C57BL/6 mice were injected intraperitoneally for 5 days with A-438079 (50-150 μmol/kg) and transplanted with an allogeneic BALB/c skin graft. Donor MHC cross-dressing was monitored in the recipient’s lymph nodes via imaging flow cytometry and graft rejection was monitored daily.
*Results: LPS + ATP induced a massive release of exosomes by macrophages. Exosome release by activated macrophages was abolished by A-438079. Of note, macrophage viability after A-438079 treatment was > 95%. Most importantly, P2X7R inhibition resulted in a near complete elimination of donor MHC cross-dressing of recipient cells in the LNs of skin-grafted mice. Skin allograft rejection was significantly delayed in A-439079-treated mice (MST: 20 days vs. 10 days for controls).
*Conclusions: This study shows for the first time the relationships between P2X7R signaling, donor exosome release and MHC cross-dressing in vitro and in skin-grafted mice. This reveals a new aspect of the role of innate immunity in transplantation.
To cite this abstract in AMA style:
Lancia HH, Carnel N, Lellouch AG, Cetrulo C, Benichou G. P2X7R Signaling Controls Exosome Release by Macrophages and Donor MHC Cross-Dressing After Skin Transplantation [abstract]. Am J Transplant. 2022; 22 (suppl 3). https://atcmeetingabstracts.com/abstract/p2x7r-signaling-controls-exosome-release-by-macrophages-and-donor-mhc-cross-dressing-after-skin-transplantation/. Accessed May 6, 2025.« Back to 2022 American Transplant Congress