CD103⁺ Conventional Dendritic Cells Are Critical for Corneal Allograft Survival

Abstract

Purpose : Conventional type 1 CD103⁺ dendritic cells (cDC1) induce immune tolerance by promoting conversion of naïve CD4+T cells to Foxp3⁺ regulatory T cells (Tregs). Herein, we examined the role of CD103⁺ DCs in corneal allograft survival.

Methods : Allogeneic corneal transplantation was performed using C57BL/6J mice as donors and BALB/c as recipients. CD103⁺ DCs were depleted in recipients with subconjunctival injection of anti-CD103-saporin conjugated antibody (SAP). On day 3, naïve Tregs, antigen specific Tregs or CD4⁺CD25^- T cells were subconjunctivally injected (1x10⁵, syngeneic ) to graft recipients and PBS injections were used as controls. Bone marrow derived induced-CD103⁺DCs (iCD103⁺, 1x104) where subconjunctivally injected to evaluate their tolerogenic efficacy, and iCD11b DCs injected mice were used as negative controls. Animals were followed up for 8 weeks. Corneas and dLNs were assessed by flow cytometry. Additionally, CD103+ DCs were FACS sorted and evaluated by PCR

Results : CD103⁺ DCs were successfully depleted in cornea(<1%,p<0.001), conjunctiva(<1%, p<0.001) and dLN(<1%,p<0.001) of SAP treated mice compared to controls by day 7. Allografts were rejected in SAP treated mice (100%, p<0.001) compared to controls (55%). Injection of Tregs moderately extended graft survival compared to SAP, but <20% (naïve,p<0.001) or <35% (antigen-specific,p<0.001) grafts survived after 8 weeks compared to controls. All the grafts were rejected in CD4⁺CD25^- T cell injected mice (p<0.001). Adoptive transfer of iCD103 DCs significantly increased graft survival to 90% (p<0.001), whereas 100% of grafts were rejected in mice inkected witht iCD11b^-(100%, p<0.001). Mice treated with iCD103 DCs showed significantly increased Treg frequency (14.3%, p<0.01) and FoxP3 expression [1.5-fold (p<0.01)] compared to either iCD11b (10.3%) or PBS (11%) treated controls. IFNγ expression was significantly decreased in dLNs (0.40%, p<0.01) of iCD103 recipient mice compared to iCD11b (2.48%) or PBS (0.90%) controls. Additionally, mRNA expression of Irf8, Itgb8, Itgae, Clec9a, Cd274 and Xcr1 genes in cornea, conjunctiva and dLN was significantly upregulated in transplanted mice (p<0.001) compared to normal.

Conclusions : These results signify the critical role of CD103⁺ DCs in promoting tolerance and allograft survival. These findings suggest a possible therapeutic potential of adoptively transferred CD103⁺ cells in preventing allograft rejection.

This is a 2020 ARVO Annual Meeting abstract.