An Acquired Immunostimulatory Function by Type-1 CD103⁺ Dendritic Cells Promotes Alloimmunity in High-risk Corneal Transplantation

Abstract

Purpose : We have shown that allograft survival in recipients at low-risk (LR) of rejection is sustained by type-1 dendritic cells (DC1) that exhibit potent immunoregulatory function defined by high IL-10 and low IL-12 expression. Herein, we examined the environment-mediated immunostimulatory reprogramming of CD103⁺ DC1 in recipients at high-risk (HR) of rejection

Methods : HR or LR allogeneic corneal transplantation was performed using C57BL/6 mice as donors and BALB/c as hosts. M290-SAP antibody was used to deplete CD103⁺ DC1. Post-transplant, kinetics of CD103⁺ DC1 were assessed. Bone-marrow-derived (BMD) CD11b and naïve CD4 T cells were co-cultured with either FACS-sorted CD103⁺ DC1 from HR recipients, or with BMD induced DC1 (iDC1) pulsed with exogenous IFN-y. Either CD103⁺ DC1 from LR recipients or iDC1 were cultured in a transwell with Th1 cells. Adoptive transfer of iDC1 pulsed with or without IFN-y was performed in HR and LR recipient mice. Readouts include flow cytometry, ELISA, RT-PCR and clinical follow-up

Results : CD103⁺ DC1 numbers were significantly higher in HR compared to LR recipients (p<0.001), and these cells expressed lower IL-10 (p<0.001), and higher IL-12 (p<0.001). While depletion of CD103⁺ DC1 led to 100% graft rejection in LR (p<0.0001), it resulted in 40% survival in HR (p<0.001). Maturation of BMD CD11b⁺ APC (measured by MHC-II and IL-12) expression and their immunogenic function (assessed by IFN-g production by sensitized Th1 cells) were significantly increased when co-cultured with either HR CD103⁺ DC1 (p<0.0001), or IFN-y-pulsed iDC1 (p<0.0001). In the presence of IFN-y producing Th1 cells, both LR CD103⁺ DC1 or BMD-iDC1 expressed low IL-10 (p<0.0001) and high IL-12 (p<0.0001). Finally, adoptive transfer of immunosuppressive iDC1 to HR recipient mice led to 90% allograft survival (p<0.0001); while adoptive transfer of IFN-y-sensing iDC1 led to 100% graft rejection in LR recipient mice (p<0.0001)

Conclusions : These results demonstrate that the transplant environment alters the function of IFN-y-sensing migratory CD103⁺ DC1. This acquired immunostimulatory function negatively impacts alloimmunity and allograft survival

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.