Effects of adeno-associated virus-vectored ciliary neurotrophic factor on retinal structure and function in mice with a P216L rds/peripherin mutation.
Past studies have shown that acute administration of ciliary neurotrophic factor (CNTF) can prolong the survival of retinal photoreceptor cells that have undergone phototoxic injury or that express gene mutations. Adenovirus-vectored CNTF has also been effective but for all of these treatments, the effect has been transient. On the other hand, adeno-associated virus-vectored minigenes offer considerable promise for long-term survival. The authors sought to provide long-term, CNTF-based protection of mouse photoreceptors expressing a dominant-negative point mutation in the rds gene by using recombinant adeno-associated virus (rAAV) to deliver minigenes that code for a secreted form of CNTF.Secreted CNTF, under control of a cytomegalovirus (CMV) or chick beta actin (CBA) promoter provided long-term, panretinal rescue of photoreceptors following single injections of rAAV vectors into the subretinal compartment. Rescue was much less effective and less reproducible when the vectors were placed in the vitreous compartment. However, there were unexpected side effects that appeared to be dose-related. One side effect was a change in rod photoreceptor nucleus phenotype, featuring an increase in euchromatin and an increase in nuclear size following subretinal injections but not intravitreal injections. These nuclear changes were panretinal when the putatively stronger CBA promoter was used but not panretinal when the CMV promoter was used. In the latter case, the nuclear changes were much more pronounced at the site of injection. Thus, chronic hyperstimulation of retinal cells with CNTF may up-regulate gene expression in photoreceptors. Based on current knowledge of retinal cell targets for CNTF, this effect may be indirect and may not represent direct stimulation of photoreceptors by CNTF.A second side effect was a paradoxical decrease in scotopic a- and b-wave amplitudes and a decrease in photopic b-wave amplitudes in the injected, rescued retina when compared to its contralateral, uninjected counterpart, in spite of the fact that these retinas had more photoreceptors than their untreated mates. The basis for these decreased ERG amplitudes may be related to changes in gene expression. The mechanisms for these side effects and proper doses of CNTF administration should be determined before human clinical trials are considered for the amelioration of inherited retinal degenerations with CNTF.
Bok
Dean
D
Department of Neurobiology, University of California, Los Angeles, CA 90095, USA. bok@jsei.ucla.edu
Yasumura
Douglas
D
Matthes
Michael T
MT
Ruiz
Alberto
A
Duncan
Jacque L
JL
Chappelow
Aimee V
AV
Zolutukhin
Sergei
S
Hauswirth
William
W
LaVail
Matthew M
MM
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D020934:Ciliary Neurotrophic Factor / Q000235:genetics / Q000502:physiology*; D004596:Electroretinography; D005136:Eye Proteins / Q000235:genetics; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D007381:Intermediate Filament Proteins / Q000235:genetics*; D008562:Membrane Glycoproteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000235:genetics*; D064531:Peripherins; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology; D017354:Point Mutation; D012160:Retina / Q000503:physiopathology; D012162:Retinal Degeneration / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D020934:Ciliary Neurotrophic Factor; D005136:Eye Proteins; D007381:Intermediate Filament Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; C578994:PRPH protein, human; C578997:PRPH2 protein, human; D064531:Peripherins; C578996:Prph2 protein, mouse