Abstract
Purpose:
Mutant alleles of the Complement Factor H (CFH) gene play an important role in the pathogenesis of age-related macular degeneration, but very little is known about its histological localization in the eye. Most studies on the distribution of CFH have been conducted in the posterior pole of the post mortem human eye. To take advantage of fresh tissue and improved morphology, we investigated Cfh distribution in the mouse posterior pole.
Methods:
C57BL/6J and BALB/c mice at 11 weeks of age were obtained from the Jackson Laboratory. All research was compliant with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. After mice were euthanized using gaseous CO2, eyes were enucleated, snap frozen and processed through freeze substitution with 3% glacial acetic acid in methanol. Eyes were then embedded in paraffin preserving orientation, and sectioned at 6 microns to obtain either coronal sections or sagittal sections through the optic disc. After post-fixation in 4% paraformaldehyde and antigen retrieval, sections were immunolabeled. Antibodies used included 2 anti-Cfh antibodies, both antibodies (goat anti-Cfh and rabbit anti-Cfh) are purified and specific for mouse Cfh sequence, from Santa Cruz Biotechnology; rabbit anti-Opsin, Blue, rabbit anti-Opsin, Red/Green, and mouse anti-Rhodopsin mAb (all from Millipore); and Fluorescein conjugated Peanut Agglutinin (PNA) or Fluorescein conjugated Wheat Germ Agglutinin (WGA) lectins (both from Vector Laboratories). Immunofluorescent conjugated secondary antibodies from Millipore were used.
Results:
Both Cfh antibodies immunolabeled a band in the outer segments of the photoreceptors. The goat anti-Cfh antibody uniquely labeled cells in the inner segments of the photoreceptors. An investigation of coronal sections employing PNA (labels membrane of cone cells) and WGA (labels membrane of rods), as well as antibodies for Cfh, rhodopsin and the two cone opsins revealed Cfh labeling within the outer segments for rods and throughout the entire cell for cone photoreceptors.
Conclusions:
The finding that Cfh may be expressed in mouse photoreceptors suggest further research is needed to confirm these results, as well as explorations of any function that Cfh may have at the RPE/photoreceptor interface.
Keywords: 554 immunohistochemistry •
648 photoreceptors •
688 retina