Horizontal Cells of the Retina Are Affected in Human Glaucoma and Accumulate Abnormal Tau Protein

Abstract

Purpose: : To determine whether abnormal tau protein accumulation contributes to the pathological process in glaucoma.

Methods: : Following institutional research ethics board approval, post–mortem normal human eyes and glaucoma eyes were collected from the Eye Bank of Canada, Ontario Division and the Ophthalmic Pathology Laboratory, University of Toronto, respectively. Fifteen glaucoma eyes with optic nerve cupping (open angle and secondary glaucoma) and 5 normal control eyes were studied, with mean ages of 72 ± 13 yrs. and 79 ± 9 yrs., respectively. Formalin–fixed, paraffin embedded sections (7 µm) from each eye were stained simultaneously with antibody to PHF–Tau that recognizes abnormally phosphorylated Ser202 residue. Positive controls were performed on neuropathological material. Negative controls were obtained by omitting the primary antibody for each control and glaucoma eye studied. Hematoxylin counter–staining was used to identify nuclei.

Results: : Abnormal tau protein immunoreactivity was observed for PHF–Tau in all glaucoma eyes. PHF–Tau signal was strong and consistently observed in the horizontal cells of the retina in human glaucoma eyes. No immunoreactivity for PHF–Tau was seen in control eyes.

Conclusions: : Abnormal tau protein accumulation in the horizontal cells of the retina is part of the pathology in human glaucoma.

Keywords: neuroprotection • pathology: human • pathobiology