Poster Presentation 14th Lorne Infection and Immunity 2024

Adeno-associated viral vectors encoding nanobodies targeting mouse and human P2X7 reduce graft-versus-host disease in a humanised mouse model (#131)

Amal Elhage 1 , Janna Hadaya 1 , Chloe Sligar 1 , Sahil Adriouch 2 , Debbie Watson 1 , Ronald Sluyter 1
  1. Molecular Horizons and School of Chemistry and Molecular Bioscience - University of Wollongong, Wollongong, NSW, Australia
  2. Unit of Pathophysiology and Biotherapy of Inflammatory and Autoimmune Diseases, French Institute of Health and Medical Research, University of Rouen, Rouen, France

Graft-versus-host disease (GVHD) is an often-fatal T cell-mediated inflammatory disorder that arises following donor stem cell transplantation. P2X7 is an extracellular ATP-gated cation channel present on immune cells. P2X7 blockade with small molecule inhibitors or a human-specific monoclonal antibody impairs GVHD in humanised mouse models. Injection of adeno-associated viral vectors (AAVs) encoding nanobodies (Nb) that block human or murine P2X7 are available, but these have not been investigated in GVHD. NSG mice were injected i.m. with 1011 viral particles encoding either green florescent protein (GFP), an anti-murine (m) P2X7 Nb or anti-murine/human (m/h) P2X7 Nb (or an equal volume of saline) on Day -21. Mice were then injected i.p. with 107 human peripheral blood mononuclear cells on Day 0 and monitored for GVHD until disease endpoint or Day 70. The anti-m/hP2X7 Nb and to a lesser extent the anti-mP2X7 Nb reduced clinical GVHD and time to disease onset, as well as histological liver and lung GVHD. The anti-m/hP2X7 Nb and less so the anti-mP2X7 Nb reduced proportions of liver human Th17 cells. Sera (collected at Day 0 and endpoint) from mice injected with AAV encoding anti-P2X7 Nbs, but not from control mice, completely blocked P2X7 activity (ATP-induced cation dye uptake) in murine J774 and/or human RPMI 8226 cells, confirming the presence of circulating anti-P2X7 Nbs at both time points. This study indicates that P2X7 blockade with anti-m/hP2X7 and less so an anti mP2X7 Nb reduces GVHD progression in humanised mice, supporting the future testing of these P2X7 biologics as a prophylactic treatment for GVHD.