XIAP effects on retinal detachment-induced photoreceptor apoptosis [corrected].
OBJECTIVE
To evaluate the ability of X-linked inhibitor of apoptosis (XIAP) gene therapy to provide neuroprotection to cells of the outer nuclear layer (ONL) of the retina after retinal detachment.


METHODS
Subretinal injections of a recombinant adenoassociated virus (rAAV) encoding either XIAP or green fluorescent protein (GFP; injection control) were performed in the left eye of Brown Norway rats. Two weeks later, retinal detachments were created at the site of viral injection by delivering sodium hyaluronate into the subretinal space. Retinal tissue was harvested at 24 hours after retinal detachment and was analyzed for caspase 3 and 9 activity. Histologic analysis was conducted on samples taken at 3 days and 2 months after detachment to confirm the presence of XIAP or GFP expression and to assess levels of apoptosis and changes in retinal thickness.


RESULTS
Caspase assays performed 24 hours after detachment confirmed an expected increase in caspase 3 and 9 activity in the detached regions of GFP-treated retinas, whereas XIAP-treated detached retinas behaved comparably to attached controls. TUNEL analysis of 3-day tissue samples showed fewer apoptotic cells in XIAP-treated detachments than in GFP-treated detachments. At 2 months after the detachment, histology and immunohistochemistry confirmed the preservation of the ONL at sites of XIAP overexpression, whereas the GFP-treated detached retinas had significantly deteriorated.


CONCLUSIONS
The results suggest that XIAP confers structural neuroprotection of photoreceptors for at least 2 months after retinal detachment.
Zadro-Lamoureux
Laura A
LA
Vision Science Program, Ottawa Health Research Institute, Ottawa, Ontario, Canada;
Zacks
David N
DN
Baker
Adam N
AN
Zheng
Qiong-Duan
QD
Hauswirth
William W
WW
Tsilfidis
Catherine
C
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D000229:Dependovirus / Q000235:genetics*; D004195:Disease Models, Animal; D015316:Genetic Therapy; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics; D020287:In Situ Nick-End Labeling; D008297:Male; D018696:Neuroprotective Agents; D020419:Photoreceptor Cells, Vertebrate / Q000201:enzymology / Q000473:pathology*; D051381:Rats; D011914:Rats, Inbred BN; D012163:Retinal Detachment / Q000201:enzymology / Q000628:therapy*; D014162:Transfection; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000235:genetics*
D018696:Neuroprotective Agents; D051636:X-Linked Inhibitor of Apoptosis Protein; D049452:Green Fluorescent Proteins; C505410:Casp3 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053453:Caspase 9