Early Production of CXCL1/KC in High Risk Corneal Allograft Regulates the Late Production of the T Cell Chemoattractants CXCL9/Mig and CXCL10/IP-10 and Causes Increased Graft Rejection

Abstract

Purpose:: We have previously shown that the increased rejection of high risk vascularized corneal allografts correlates with increased recruitment of T cell and the early production of the chemokine CXCL1/KC. The goal of this project is to understand the mechanisms behind this process.

Methods:: Murine orthotopic allogeneic corneal allotransplants (Balb/c to C57BL/6) were performed into non-vascularized and vascularized high risk recipients (day 0). Chemokine production of CXCL1/KC and the T cell chemoattractants CXCL9/Mig and CXCL10/IP-10 were determined by ELISA at days 3, 7, 11 and 14. To study the role of CXCL1/KC, high risk corneal allografts recipients were treated with systemic and subconjunctival injections of KC antisera or control on days -1, 0 1, 3, 5, 7, 9, 11. Neutralization of CXCL1/KC was confirmed in corneal extracts by ELISA. Graft survival was scored and the number of CD4 T cells was quantified by immunohistochemistry. Corneas from non-treated and KC antiserum treated mice were harvested at different time points after surgery and extracts were tested for the presence of CXCL9/Mig and CXCL10/IP-10.

Results:: Rejection of high risk corneal allografts correlated with increased production of CXCL1/KC at day 3 and the up-regulation of the T cell chemoattractants CXCL9/Mig and CXCL10/IP-10 at day 11 after transplantation. In vivo neutralization of CXCL1/KC (confirmed by ELISA) resulted in a 50% graft survival compared to 0% of control treated mice. Increased graft survival correlated with decreased recruitment of CD4 T cells. Moreover, the early blockade of CXCL1/KC resulted in a significant down-regulation of late CXCL9/Mig and CXCL10/IP-10 production in surviving high risk corneal allografts compared to controls.

Conclusions:: The recruitment of T cells and graft rejection in high risk corneal allografts is mediated by the orchestrated production CXC chemokines in the graft. Early CXCL1/KC production regulates this process by controlling the late production of T cell chemoattracants CXCL9/Mig and CXCL10/IP-10. The local neutralization of CXCL1/KC could represent a novel form of therapy that blocks the recruitment of allo-specific T cells into the graft to improve high risk corneal allograft survival.

Keywords: transplantation • immunomodulation/immunoregulation • cornea: basic science