An alternative for extracorporeal photopheresis: 8‐methoxypsoralen and UVA‐treated leucocytes from allogeneic donors improve graft‐versus‐host disease in mice

Abstract

Background and Objective Extracorporeal photopheresis (ECP) is an important immune tolerance inducing therapy for graft-versus-host disease (GvHD). However, a sufficient number of ECP cycles cannot be performed in patients with severe GvHD and contraindications for apheresis. Allogeneic sources of leucocytes for use as ECP treatment would be of great benefit. Therefore, this study aimed to test the therapeutic potential of novel sources of leucocytes for ECP. Materials and MethodsGraft-versus-host disease mice were treated with ECP using therapeutic cells from different allogeneic sources. Splenocytes were incubated with 8-methoxypsoralen (8-MOP), irradiated with UVA light and injected into GvHD mice as a model for ECP. ResultsThe therapy with 8-MOP/UVA-treated cells from healthy mice of the bone marrow transplantation (BMT) donor strain reduced the GvHD symptoms, at least in a model of chronic GvHD. In the acute GvHD model, 8-MOP/UVA-treated cells from the BMT donor or recipient strain did not show significant improvements in GvHD symptoms or survival time. Pre-activation of cells by mixed lymphocyte reactions before 8-MOP/UVA treatment also failed to result in significant differences in survival time or GvHD score. In contrast, ECP with third-party 8-MOP/UVA-treated cells from a HLA-mismatched donor resulted in a mean survival time of 37 days compared to 21 days in the control group.Conclusion In our analysis of novel allogeneic leucocyte sources for ECP, we could demonstrate that the source of the 8-MOP/UVA-treated cells is crucial. The underlying immunologic effect of allogeneic 8-MOP/UVA-treated cells needs to be investigated in future studies.

CD11c+ dendritic cells mediate antigen-specific suppression in extracorporeal photopheresis

“…Other preclinical in‐vivo models showed that ECP suppressed allogeneic skin graft rejection [25–27], cardiac allograft rejection [28–30], GVHD [31–35], CHS [19,20,22,23,36], experimental allergic encephalomyelitis [37,38], pathology in lupus‐prone mice [39,40], type 1 diabetes in non‐obese mice [41] and collagen‐induced arthritis (CIA) [42]. The experimental design of these studies involved a donor of ECP‐treated cells, incubation of donor cells with 8‐MOP (range = 100–250 ng/ml), UVA irradiation (range = 1–5 J/cm 2 ) of donor cells and i.v.…”

“…minor or major histocompatibility antigen of the graft donor) is not present in the ECP‐treated inoculum and immunosuppressive effects are not donor‐specific. The same holds true in experimental ECP treatment of GVHD if a naive ECP cell donor is syngeneic to the bone marrow donor [32,34,35], as pathological T cell responses in the setting of active GVHD are directed to the recipient but not donor, minor or major histocompatibility antigens. In these protocols, even third‐party ECP cell donors [32,35] mediated immunosuppressive effects in the recipient.…”

“…The same holds true in experimental ECP treatment of GVHD if a naive ECP cell donor is syngeneic to the bone marrow donor [32,34,35], as pathological T cell responses in the setting of active GVHD are directed to the recipient but not donor, minor or major histocompatibility antigens. In these protocols, even third‐party ECP cell donors [32,35] mediated immunosuppressive effects in the recipient. The antigen‐independent effects of ECP treatment (that are obvious in these experimental protocols) may mirror immunomodulating effects that are also seen in other apoptotic cell‐based therapies (for review see [43]).…”

Extrakorporale Photopherese mit UVC-behandelten Leukozyten im Vergleich zu 8-MOP/UVA-behandelten Leukozyten zur Therapie der akuten graft-versus-host disease im Mausmodell

“…Auch Budde et al (2014) konnten diese Wirkung in einem Mausmodell zur akuten GvHD mit totalem MHC-mismatch zeigen. Außerdem konnten Budde et al (2018) zeigen, dass eine ECP-Therapie mit Splenozyten einer dritten unbeteiligten Mauslinie bei einem MHC-mismatch-Modell für akute GvHD zu einer Verbesserung der Überlebenszeit und des klinischen Krankheitsbilds führt.…”

“…Die ECP wurde mit den Splenozyten einer C3H-Maus durchgeführt. Die Nutzung von Splenozyten einer dritten unabhängigen Mauslinie für die ECP zeigte in Untersuchungen vonBudde et al (2018) einen therapeutischen Effekt. Bisher wurden die Splenoytzen von ebenfalls mit akuter GvHD induzierten und erkrankten Tieren verwendet(Budde et al 2014).…”