Abstract
Purpose:
Alpha A crystallin is known to be expressed in rodent retina. Here we sought to determine the expression pattern in human retina, and see whether the expression differs with retinal pathology.
Methods:
Post mortem tissue from healthy donors and donors with known retinal pathologies, such as diabetic retinopathy (DR) and central retinal vein occlusion (CRVO), were investigated. Paraformaldehyde fixed tissue was sectioned and immunohistochemistry was undertaken, looking for distribution patterns of alpha A crystallin.
Results:
Alpha A Crystallin was found to be highly expressed by Müller cells in and around the fovea. Whereas expression in peripheral retina was comparatively low. However, in response to stress alpha A crystallin was strongly upregulated in retinal Müller cells in the peripheral retina. Reactive Müller cells (glial fibrillary acidic protein, GFAP positive) in retinas from type II diabetic and diabetic retinopathy donors expressed alpha A crystallin at high levels. Interestingly, in a case of CRVO in an ischemic, atrophic area of the retina alpha A Crystallin was upregulated, but GFAP was not.
Conclusions:
Alpha a crystallin is expressed under normal conditions in a subset of Müller cells at the fovea, its function in this location is as yet unknown. Nevertheless, this represents the first demonstration of differential gene expression of Müller cells in different areas of the retina. Furthermore, alpha A crystallin may also be a suitable marker of chronic stress and retinal pathology in the peripheral human retina.