Abstract
Purpose :
We have previously shown that a diabetic state induces an altered corneal microenvironment that alters the immune homeostasis of the cornea, leading to increased APC (antigen-presenting cell) maturation. Herein we examine the host alloimmune response to allografts from diabetic donors, in particular the role of graft-borne APC.
Methods :
Type I diabetes mellitus (DM) was induced in C57BL/6 mice by injecting streptozocin (STZ). On day 56, corneas were either harvested and assessed through flow cytometry and immunofluorescence or transplanted into non-DM BALB/c recipient mice. Two weeks after transplantation, grafted corneas and draining lymph nodes (DLN) were analyzed by flow cytometry. In addition, IFNγ production by alloreactive CD4+ Th1 cells was quantified by flow cytometry and ELISPOT assay to evaluate the contribution of graft donor APC to host sensitization.
Results :
APC (CD45+CD11b+) in DM corneas showed higher frequency (p=0.0001) and enhanced expression of the maturation markers (MHC-II, CD80, CD86, and CCR7) (p=0.0001) when compared to APC from non-DM corneas. Following transplantation, the frequency of mature migratory CD45+CD11b+ APC was significantly increased in the DLN of recipients receiving grafts from DM donors as compared to non-DM donors (p<0.001). IFNγ+ production by alloreactive CD4+ Th1 cells in hosts receiving grafts from DM donors was higher (p<0.001) as compared to non-DM donors. DM graft-derived APC were significantly more potent in sensitizing CD4+ Th1 cells (direct pathway of sensitization) (p<0.001) compared to host APC (indirect pathway). Finally, DM allografts had a higher failure rate when compared to non-DM allografts (100% vs. 52%, p<0.001).
Conclusions :
Our results demonstrate that a donor diabetic state leads to increased homing and maturation of corneal APC, and that following transplantation graft-borne APC swiftly migrate to the DLN to increase host sensitization. Together these changes may lead to increased graft rejection / failure when corneal transplants are derived from diabetic donors.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.