The effect of the diabetic state in donors on resident corneal immune cells and graft survival

Abstract

Purpose : The diabetic state promotes infiltration and maturation of antigen presenting cells (APC) in the cornea. The effect of these corneal APCs on outcomes of corneal transplantation is yet to be elucidated. In this study, we investigate the effect of altered immune milieu in corneas from diabetic donors transplanted to normal recipients, using a validated murine model of corneal allotransplantation.

Methods : Type I diabetes mellitus was induced in C57BL/6 mice by injecting 50mg/kg streptozocin (STZ) for 5 days. The altered glycemic state was confirmed by a self-monitoring glucometer. On day 25, mice with blood glucose levels of 300mg/dL were considered diabetic. The corneas from diabetic mice were harvested and grafted onto normal BALB/c recipient mice, or used for flow cytometry analysis. Recipient mice were followed up for 8 weeks using slit-lamp biomicroscopy. Two weeks after the transplantation, both cornea and draining lymph node of recipient mice were analyzed using flow cytometry.

Results : A significantly higher frequency of CD11b⁺ cells (82±2.5%, p=0.0009) and higher expression of MHC-II (fold increase p=0.048) were observed in corneas from diabetic donors compared to normal mice. The allograft rejection was faster in recipients of diabetic donor corneas compared to recipients with normal donors. CD11b⁺ cells frequency (2.58±0.2%;p=0.014) as well as their maturation markers such as MHC-II (p=0.006), CD80 (p=0.007) and CD86 (p=0.03), were significantly increased in recipients corneas with diabetic donors compared to recipients with normal donors. The frequency of CD11b⁺APCs (0.9±0.06%; p=0.047) and IFNγ⁺ T-cells (2±0.18%; p=0.005) were significantly higher in dLNs of mice receiving grafts from diabetic donors compared to recipients with normal donors. Conversely, the frequency of FoxP3⁺ Tregs (13.3±0.2%; p=0.012), and their expression of IL-10 (p=0.07) and TGFβ1 (p=0.0085) were significantly reduced in mice receiving grafts from diabetic donors compared to recipients with normal donors.

Conclusions : Our data suggest that type I diabetes mellitus induces maturation of resident corneal immune cells and; consequently, diabetic donor corneas may precipitate graft immune rejection in recipient mice.

This is a 2020 ARVO Annual Meeting abstract.