Topical application of FTY720 and cyclosporin A prolong corneal graft survival in mice

PURPOSE To investigate the effects of topical FTY720 and cyclosporin A (CsA) on allogeneic corneal transplantation in mice. METHODS A total of 75 BALB/c mice received corneal grafts from C57BL/6 donors. Recipients were treated with 0.1%, 0.3%, or 0.5% FTY720 ophthalmic gel or 1% CsA eye-drops after the graft (controls received no treatment). The number of cluster of differentiation (CD)4+ T cells and CD4+CD25+forkhead box P3 (Foxp3)+ regulatory (Treg) cell phenotypes were measured by flow cytometry. Cytokine mRNA expression in corneal grafts was analyzed by real-time quantitative PCR. CD4 + T cells and cytokines in corneal samples were identified by immunohistochemical staining. RESULTS Corneal graft survival was prolonged by treatment with topical 0.5% FTY720 (mean survival time [MST], 24.1±1.6 days) or 1% CsA eye-drops (MST 25.0±1.9 days) compared with controls (MST, 13.4±0.5 days; n=9, both p<0.01). Topical 0.5% FTY720 treatment significantly increased the percentages of CD4 + T (p<0.05) and Treg cells (p<0.01; n=5) in the cervical lymph nodes compared with controls. Transforming growth factor-β1 (TGF-β1) mRNA transcription in corneal grafts after topical 0.5% FTY720 increased (p<0.05, n=3), while interleukin-2 (IL-2) and interferon-γ (IFN-γ) mRNA expression in corneal grafts treated with 1% CsA decreased (p<0.01, p<0.05, respectively). These cytokine results were paralleled by similar immunohistochemical staining. Topical 0.5% FTY720 and 1% CsA treatment reduced the infiltration of CD4+ Tcells in the grafts. CONCLUSIONS Topical 0.5% FTY720 and 1% CsA can effectively prolong allogeneic corneal graft survival in mice. Treatment with topical 0.5% FTY720 increases the percentage of CD4+ T cells and the percentage of Treg cells in cervical lymph nodes. The 0.5% FTY720 increased TGF-β1 mRNA expression and decreases infiltration of CD4+ T cells in corneal grafts, while topical 1% CsA down-regulated the expression of IL-2 and IFN-γ.