In Vivo Visualization of Early Inflammatory Cell Recruitment in Corneal Transplantation using MAFIA and EGFP–chimeric mice

Abstract

Abstract: : Purpose: To characterize in vivo the early recruitment of bone marrow–derived and dendritic cells into the cornea following syngeneic and allogeneic corneal transplantation. Methods: Orthotopic syngeneic (C57BL/6 to C57BL/6) and allogeneic (Balb/c to C57BL/6) corneal grafts were perfomed in MAFIA and EGFP–chimeric mice. MAFIA mice (macrophage fas induced apoptosis) express the EGFP reporter gene in all endogenous macrophages and dendritic cells under the control of the CFMS promoter. In contrast the EGFP chimeric mice express this reporter gene in all bone marrow–derived cells. In vivo time–lapsed images using fluorescent stereomicroscopy were obtained at different early time points after transplantation. Whole mount corneas were prepared and analyzed ex vivo with 3D recontruction analysis of confocal images. Results: Within 24 hours, bone marrow–derived inflammatory cells can be detected accumulating in the recipient bed of EGFP–chimeric mice that received a syngeneic and allogeneic graft. After 48 hours more, EGFP bone marrow–derived cells were present in the allogeneic transplants. MAFIA mice corneal transplants demonstrated dendritic cell migration into the recipient bed, and this was distinctively higher in the allogeneic transplant. Moreover, a significantly higher population of EGFP–positive dendritic cells migrated into the allogeneic graft tissue. Conclusions: In vivo visualization of immune responses in these novel models demonstrate an abundant early recruitment of bone marrow–derived inflammatory cells into the recipient bed of corneal allogeneic transplants. Moreover, the early migration of host dendritic cells into allogeneic graft tissue is apparent and implicates the important role of indirect immune allorecognition in corneal transplantation.

Keywords: transplantation • immunomodulation/immunoregulation • antigen presentation/processing