Immunostaining of heat shock proteins in the retina and optic nerve head of normal and glaucomatous eyes

Purpose: To examine immunostaining of 60-kd and 27-kd heat shock proteins (HSP 60 and HSP 27), which are known to increase cell survival in response to stress, in glaucomatous retina and optic nerve head. Methods: Six postmortem eyes from patients with primary open-angle glaucoma, 6 eyes from patients with normal-pressure glaucoma, and 6 eyes from age-matched normal subjects were studied by immunohistochemistry. The sections of the retina and optic nerve head were examined after immunostaining with antibodies to HSP 60 and HSP 27. Results: The intensity of the immunostaining and the number of labeled cells for heat shock proteins (HSPs) were greater in retina sections from glaucomatous eyes than in sections from normal eyes from age-matched donors. Retinal immunostaining of HSP 60 was prominent in the retinal ganglion cells and photoreceptors, whereas immunostaining of HSP 27 was prominent in the nerve fiber layer and ganglion cells as well as in the retinal vessels. In addition, retinal immunostaining of these HSPs exhibited regional and cellular differences. Optic nerve heads of glaucomatous eyes exhibited increased immunostaining of HSP 27, but not HSP 60, which was mostly associated with astroglial cells in the lamina cribrosa. Conclusion: The increased immunostaining of HSP 60 and HSP 27 in the glaucomatous eyes may reflect a role of these proteins as a cellular defense mechanism in response to stress or injury in glaucoma. Clinical Relevance: These findings suggest that immunoregulation is an important component of glaucomatous optic neuropathy.