Unique patterns of CD8+ T-cell-mediated organ damage in the Act-mOVA/OT-I model of acute graft-versus-host disease

Abstract

T-cell receptor (TCR)-transgenic models of acute graft versus host disease (aGvHD) offer a straightforward and highly controlled approach to studying mechanisms and consequences of T-cell activation following allogeneic hematopoietic stem cell transplantation (aHSCT).Here we report that aHSCT involving OT-I mice as donors, carrying an ovalbumin-specific CD8+ TCR, and ActmOVA mice as recipients, expressing membrane-bound ovalbumin driven by the -actin promoter, induces lethal aGvHD in a CD8+ T cell-dependent, highly reproducible manner, within 4-7 days. Tracking of UBC-GFP/OT-I graft CD8+ T-cells disclosed heavy infiltration of the gastrointestinal tract, liver and lungs at the onset of the disease, and histology confirmed hallmark features of gastrointestinal aGVHD, hepatic aGvHD, and aGvHDassociated lymphocytic bronchitis in infiltrated organs. However, T-cell infiltration was virtually absent in the skin, a key target organ of human aGvHD, and histology confirmed absence of cutaneous aGVHD, as well. We show that the model allows studying CD8+ T-cell responses in situ, as selective recovery of graft CD45.1/OT-I CD8+ T-cells from target organs is simple and feasible by automated tissue dissociation and subsequent cell sorting. Assessment of interferon-gamma production by flow cytometry, granzyme-B release by ELISA, TREC assay and whole genome gene expression profiling confirmed that isolated graft CD8+ T-cells remained intact, underwent clonal expansion and exerted effector functions in all affected tissues.Taken together, these data demonstrate that the OT-I/Act-mOVA model is suitable to studying CD8+ T cellmediated effector mechanisms in a disease closely resembling fatal human gastrointestinal and hepatic aGVHD that may develop after aHSCT using HLA-matched unrelated donors.

High sensitivity of host Helios+/Neuropilin‐1+ Treg to pretransplant conditioning hampers development of OX40bright/integrin‐β7+ regulatory cells in acute gastrointestinal GvHD

“…Allogeneic HSCT was performed to induce murine experimental acute GI GvHD as described earlier [39], with modifications implemented to ensure conformity with the European Directive 2010/63/EU by refining protocols to reduce weight loss and host mortality in order to reduce animal suffering and animal numbers used, and in order to minimize the presence of graft Treg in the host by day 4 post-aHSCT. Briefly, B6 act-mOVA mice received 11 Gy total body irradiation (TBI) in two doses, 3 h apart (5.5 Gy each, 137.37 cGy/min).…”