Abstract
Purpose::
The presence of myocilin, MYCO, which we have previously demonstrated in the hypertensive spontaneous open angle Beagle model is being investigated in dogs of different breeds with glaucoma, being mostly primary with one example of secondary. We have examined the localization the MYOC protein in these glaucomatous canine eyes by immuno-histochemistry.
Methods::
Paraffin-embedded specimens from the anterior uveas of 12 dogs (Chow, Cocker Spaniel, Italian Greyhound, Miniature Poodle, Yorkshire Terrier and Mixed Breed) with primary or secondary glaucoma (7-14-yrs-old) and age-matched normals (Beagles and Miniature Schnauzers) were sectioned and incubated with primary antibody, rabbit polyclonal anti-human MYOC IgG (Santa Cruz Biotechnology ) overnight at 4 degrees C. Specimens were incubated with secondary antibody either with biotinylated link followed by peroxidase-labeled streptavidin and then by substrate-chromogen for light microscopy.
Results::
Within normal canine specimens, cells of the nonpigmented epithelium (NPE) of the CB processes stained diffusely. Smooth muscle of the iris and ciliary body stained lightly positive, as well as most resident stromal and vascular endothelial cells. Within the glaucomatous specimens, localization within the NPE varied, being localized in clusters of cells in some instances, having apical localization throughout the NPE in others and strong positive localization within much of the cytoplasm of the NPE in others. Reaction within the ciliary process stroma varied as well. While trabecular meshwork (TM) cells and trabeculae and adjacent sclera were labeled lightly in the normals, various intensities of staining were observed within the area of TM cells and adjacent sclera among the glaucomatous specimens. In most instances the iridocorneal angles were collapsed, especially anteriorly. Still, MYOC localization was observed though variable in intensity within the collapsed areas.
Conclusions::
Immunolocalization of MYCO in glaucomatous canine eyes of different individuals representing a number of breeds was successfully observed in every instance. The variations found among the individual dogs may relate to differences in the manner that each primary glaucoma progresses for each respective breed. The state of progression most likely has influence as well, having been more advanced in some than in others. And, differences in therapeutic measures may have also played a role in the way MYOC has been expressed in these dogs.
Keywords: outflow: trabecular meshwork • immunohistochemistry • ciliary processes