Transgenic mice expressing variants of complement factor H develop AMD-like retinal findings.
OBJECTIVE
Complement factor H (Cfh) is a key regulator of the alternative complement pathway. A Cfh variant (Y402H) increases the risk for AMD. The purpose of this study was to develop a pathophysiologically relevant animal model of AMD based on this genetic risk factor.


METHODS
The authors generated chimeric Cfh transgenic mouse lines using two constructs consisting of the human CFH sequence for SCR6-8 (with either 402Y or 402H), flanked by the mouse sequence for SCR1-5 and SCR9-20. They tested the expression of the transgenic mRNA and protein molecules and examined the mice at 12 to 14 months of age for clinical and histologic retinal changes.


RESULTS
Nuclease protection assay and qRT-PCR analysis demonstrated transgenic mRNA expression in the liver and in the posterior segment of the eye. Western blot analysis showed that the transgenic proteins are present in the circulation at levels comparable to those of mouse Cfh. The chimeric proteins were found to be functional, as demonstrated by their ability to restore physiological serum levels of complement component C3 in Cfh KO mice. Clinical examination showed subretinal drusen-like deposits. Histology demonstrated an accumulation of subretinal cells that stained with a macrophage/microglia marker. Basal laminar deposits, long-spaced collagen, and increased numbers of lipofuscin granules were seen on electron microscopy. Immunohistochemistry showed a thicker sub-RPE band of C3d staining.


CONCLUSIONS
Chimeric Cfh proteins led to AMD-like characteristics in mice. This may represent a good model for studying the role of complement and other components of the immune system in early AMD.
Ufret-Vincenty
Rafael L
RL
Department of Ophthalmology, UT Southwestern Medical Center, Dallas, Texas 75390-9057, USA. rafael.ufret-vincenty@utsouthwestern.edu
Aredo
Bogale
B
Liu
Xinran
X
McMahon
Anne
A
Chen
Peter W
PW
Sun
Hui
H
Niederkorn
Jerry Y
JY
Kedzierski
Wojciech
W
D000818:Animals; D015153:Blotting, Western; D002678:Chimera; D003176:Complement C3 / Q000378:metabolism; D017242:Complement Factor H / Q000235:genetics*; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005838:Genotype; D008099:Liver / Q000378:metabolism; D008268:Macular Degeneration / Q000235:genetics* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D057972:Posterior Eye Segment / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors
D003176:Complement C3; D012333:RNA, Messenger; D017242:Complement Factor H