Autoantibody against neuron-specific enolase found in glaucoma patients causes retinal dysfunction in vivo.

Abstract

In our recent paper, we have reported the presence of serum autoantibody against neuron-specific enolase (NSE) in patients with glaucoma. The purpose of the present study was to investigate further the pathological effects of anti-NSE antibody on retina by comparing them with the effects induced by N-methyl-D-aspartate (NMDA). Either a glaucoma patient's serum or purified anti-NSE antibody, or 10-40 mM NMDA was intravitreously administered into Lewis rat eyes, and electrophysiological, histopathological, and biochemical evaluations were performed. In addition, the neuroprotective effects of anti-glaucoma drugs, such as timolol, betaxolol, nipradilol, and isopropyl unoprostone, and a calcium antagonist were also studied using these animal models. Electron microscopy revealed that intravitreal administration of a glaucoma patient's serum, which immunoreacted with retinal 50 kDa in Western blot analysis, and purified anti-NSE antibody induced retinal ganglion cell apoptosis in rat eyes. Functionally, these eyes showed a significant decrease in electroretinogram (ERG) responses and a remarkable decrease in rhodopsin phosphorylation reaction. These changes were comparable to the effects observed after the intravitreal administration of 20 mM NMDA. Co-administration of nipradilol, an alpha- and beta-blocker, with anti-NSE antibody or 20 mM NMDA caused marked recovery of the affected ERG responses within 2 weeks. In contrast, administration of timolol or betaxolol showed no recovery effect on the ERG responses. Among these drugs, only betaxolol showed a recovery effect on NMDA-induced decrease of rhodopsin phosphorylation. Nilvadipine functioned beneficially on both impaired ERG and rhodopsin phosphorylation reactions observed in rat eyes injected intravitreously with anti-NSE antibody or NMDA. These effects of nilvadipine were not changed by the addition of endothelin-1. In contrast, isopropyl unoprostone had no effect on these functions. These observations suggest that serum autoantibody against NSE found in some patients with glaucoma induces retinal dysfunction in vivo, similarly to NMDA.