Inhibition of retinal detachment-induced apoptosis in photoreceptors by a small peptide inhibitor of the fas receptor.
Purpose. To test the effect of a small peptide inhibitor (Met12) of the Fas receptor on the activation of extrinsic and intrinsic apoptosis pathways after retinal detachment. Methods. Retinal-RPE separation was created in Brown Norway rats by subretinal injection of 1% hyaluronic acid. Met12, derived from the Fas-binding extracellular domain of the oncoprotein Met, was injected into the subretinal space at the time of separation. A mutant peptide and vehicle administered in a similar fashion acted as inactive controls. The extrinsic apoptotic pathway was induced in 661W cells using a Fas-activating antibody in the presence or absence of Met12. Caspase 3, caspase 8, and caspase 9 activities were measured with calorimetric and luminescent assays in retinal extracts and cell lysates. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) was performed in retinal sections 3 days after separation. Histology was performed in retinal sections 2 months after retinal detachment. Results. Met12 inhibited Fas-induced caspase 8 activation in 661W cells. Similarly, administration of Met12 into the subretinal space inhibited the activation of caspase 3, caspase 8, and caspase 9 after retinal detachment. This corresponded to a decreased level of TUNEL-positive staining of photoreceptors after retinal-RPE separation in animals that received Met12, but not inactive mutant, peptide treatment. After 2 months, the outer nuclear layer was significantly thicker, and the photoreceptor count was higher in animals treated with subretinal Met12. Conclusions. The small peptide Met12 may serve as a photoreceptor-protective agent in the setting of retinal-RPE separation.
Department of Ophthalmology and Visual Sciences, W. K. Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, USA.
Cagri G
CG
Besirli
Nicholas D
ND
Chinskey
Qiong-Duan
QD
Zheng
David N
DN
Zacks
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002452:Cell Count; D018929:Cell Culture Techniques; D002470:Cell Survival; D020287:In Situ Nick-End Labeling; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology*; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects / Q000473:pathology*; D051381:Rats; D011914:Rats, Inbred BN; D012163:Retinal Detachment / Q000517:prevention & control*; D019014:fas Receptor / Q000037:antagonists & inhibitors* / Q000378:metabolism
D009842:Oligopeptides; D019014:fas Receptor; C505528:Casp8 protein, rat; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9