Abstract
Purpose: :
To investigate the mechanism of lymphangiogenesis in graft rejection process, we determined the expression level of several lymphangiogenic markers in rejected human corneal bed through immunohistochemical and molecular biologic works.
Methods: :
Seventeen recipient corneas were secured from the patients who performed re-keratoplasty for graft rejection after penetrating keratoplasty. All corneas showed signs of active rejection such as Khodadoust line before re-keratoplasty. The corneas were cut in half to make two pieces of the same size and one piece was used for immunostaining and the other was used for RT-PCR for each corneas. To determine the lymphangiogenic markers, expression of vascular endothelial growth factor (VEGF)-A, VEGF-C, VEGF-D, VEGFR-2, VEGFR-3, fibroblast growth factor-2 (FGF-2), and LYVE-1 were investigated. Two normal corneas were included as control.
Results: :
From the immunostaining of LYVE-1, we found many LYVE-1 expressed cells in anterior and posterior stroma and lymphatic vessels growing into the paracentral cornea. The expressions of VEGF-A, VEGFR-2, and LYVE-1 were upregulated in rejected cornea compared to the normal. In contrast, expressions of VEGF-C, VEGF-D, and VEGFR-3 were not changed in rejected graft. By the quantitative real time RT-PCR data, mRNA for VEGF-A, VEGFR2 expression ratio (keratoplastic cornea/normal cornea) was 8.2 in VEGF-A, 3.9 in VEGFR2. However, mRNA for VEGF-C, VEGF-D, and VEGF3 were 1.3, 0.9, and 1.2, respectively. FGF-2 did not show the increment in rejected corneal bed.
Conclusions: :
These findings may suggest that VEGF-A and VEGFR2 axis is more important pathway for corneal graft rejection and lymphangiogenesis than VEGF-C, -D, or VEGFR3 axis.
Keywords: cornea: basic science • immune tolerance/privilege • vascular endothelial growth factor