Abstract
Purpose: :
Immune rejection mediated by T-lymphocytes remains the leading cause of keratoplasty failure. Given the dynamic nature of the immune system, migration of immune cells into grafts is critical during rejection. Here we studied the dynamic behavior of T-lymphocytes that infiltrate corneal allografts using high-resolution in vivo imaging.
Methods: :
Corneal allotransplants and syngenic transplants were performed with recipient B6.129P2-Cxcr6tm1Litt/J which express GFP in T-lymphocytes. Noninvasive fluorescence confocal imaging of the grafts and the infiltrating GFP+ T-lymphocytes was performed longitudinally. Graft infiltration by GFP+ T-lymphocytes and their in vivo dynamic behavior in the grafts were quantified using z-stack images and time-lapse recordings (20 min).
Results: :
GFP+ T-lymphocytes infiltrated both syngeneic and allogeneic recipient corneas as early as post-operative day (POD) 1. However, noticeable infiltration of allogeneic but not syngeneic grafts was observed between POD3 and POD7. The number of GFP+ T-cell within the allograft increased significantly by POD14, coinciding with evident graft rejection. Dynamic analysis of 3-D time-lapse recordings (20 min) revealed different dynamic behavior by T-lymphocytes in syngeneic versus allogeneic recipients. Early infiltrating GFP+ T-cells (POD1 - POD3) exhibited migratory movement toward the grafts in allogeneic but not syngeneic recipients. By POD14, T-lymphocytes moved vividly within the allografts, whereas the fewer T-lymphocytes observed within syngeneic grafts were primarily round and stationary. The displacement (straight line from beginning to end of travel) and displacement rate (displacement/total time) of GFP+ T-cells in allografts were significantly higher than those in syngeneic grafts. Motile T-cells within allografts vividly changed shape from elongated to amoeboid as they moved through the graft stroma.
Conclusions: :
Using longitudinal in vivo imaging, we revealed the infiltration kinetics and movement dynamics of GFP+ T-lymphocytes during corneal allografts rejection, while syngeneic grafts showed little to no infiltration. Moreover, a highly dynamic behavior by GFP+ T-lymphocytes was observed in allogeneic but not syngeneic grafts. Our results suggest an important relationship between T-lymphocyte motility and allorejection and strengths our hypothesis of using anti-chemoattractant therapy to influence this and increase graft survival.
Keywords: immunomodulation/immunoregulation • transplantation • inflammation