Abstract
Purpose: :
. To determine whether CFH is produced locally by RPE and its production linked to RPE cell death or malfunction leading to age-related macular degeneration (AMD).
Methods: :
. CFH expression was studied in two freshly enucleated (<24 hours) human globes. RPE cells were harvested and CFH expression was investigated by western blotting and RT-PCR. Results were confirmed with immunohistochemistry. Similar, assays were also conducted in C57B6 mouse. The change in CFH expression after sublethal injury of RPE cells was investigated after intravenous infusion of sodium iodate (20 mg/kg) in 13 C57B6 mice. Ten days after the infusion the animals were sacrificed and the amount of CFH was assessed by western blotting, RT-PCR and immunohistochemistry. Saline injected animals were taken as controls. Also, change in CFH expression in the liver, brain, cornea and lens was determined as internal controls.
Results: :
Western blotting and RT-PCR confirmed the expression of CFH in the human and mouse RPE. High amounts of CFH were also detected in the brain, liver and cornea by western blot analyses. Immunohistochemistry revealed expression of CFH in the RPE as well. However, robust amounts of CFH expression was also discovered in human photoreceptor inner and outer segments and in the ganglion cell layer. A similar staining pattern was also observed in the mouse retina. Sublethal injury increased the expression of CFH protein in the RPE cells, as well as in the photoreceptors and ganglion cells.
Conclusions: :
CFH expression is not limited to RPE cells in the mammalian eye but can also be observed in the photoreceptors and ganglion cells. Sublethal injury of the RPE cells resulting increased expression of CFH protein. This expression pattern supports the hypothesis that CFH expression may phylogenically evolve as a protective mechanism to avoid the clearance of these cells in the case of sublethal injury.
Keywords: age-related macular degeneration • immunomodulation/immunoregulation • retinal pigment epithelium