Keratocyte apoptosis and failure of corneal allografts.
BACKGROUND
Murine models of high-risk and low-risk corneal transplantation were used to determine the role of keratocyte apoptosis in the failure of orthotopic allogeneic corneal transplants.


METHODS
Normal (low-risk, low-rejecting) and inflamed/vascularized (high-risk, high-rejecting) BALB/c recipient beds received fully mismatched C57BL/6 corneal allografts. Apoptosis was detected in the corneal stroma at various time points using an in situ terminal deoxynucleotide tranferase-mediated dUTP nick-end labeling assay, and ex vivo via Western analysis for active caspase-3. Apoptosis was also measured in a (donor-type) C57BL/6 keratocyte cell line after stimulation of Fas or via use of various pro-inflammatory cytokines.


RESULTS
Significantly more apoptotic cells were present in the stroma of rapidly rejecting high-risk corneal allografts compared with low-risk grafts. Apoptotic cells were shown to be nearly uniformly CD45 and hence of a non-hematopoetic lineage. Apoptosis, however, was not present in highly inflamed but ungrafted corneas. Apoptosis was induced in keratocytes in vitro by dual stimulation with agonistic Fas mAb and either interleukin-1beta or tumor necrosis factor-alpha.


CONCLUSIONS
Apoptosis of resident non-bone marrow-derived fibroblastic cells of the corneal stroma is strongly correlated with the failure of corneal allografts, particularly in the highly inflamed microenvironment of the high-risk allograft.
Beauregard
Clay
C
Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA.
Huq
Syed O
SO
Barabino
Stefano
S
Zhang
Qiang
Q
Kazlauskas
Andrius
A
Dana
M Reza
MR
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000032:analysis; D002460:Cell Line; D003319:Corneal Stroma / Q000166:cytology* / Q000637:transplantation*; D016039:Corneal Transplantation / Q000276:immunology*; D005347:Fibroblasts / Q000201:enzymology / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D006084:Graft Rejection / Q000473:pathology / Q000503:physiopathology*; D007249:Inflammation / Q000473:pathology / Q000503:physiopathology; D007375:Interleukin-1 / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018124:Receptors, Tumor Necrosis Factor / Q000276:immunology; D014184:Transplantation, Homologous / Q000473:pathology / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019014:fas Receptor
D000911:Antibodies, Monoclonal; C491899:Fas protein, mouse; D007375:Interleukin-1; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases