Anti-Neurotrophic Effects from Autoantibodies in Adult Diabetes Having Primary Open Angle Glaucoma or Dementia

Mark B Zimering,Robert J Donnelly,Thomas E Moritz

doi:10.3389/fendo.2013.00058

Abstract

Aim: To test for anti-endothelial and anti-neurotrophic effects from autoantibodies in subsets of diabetes having open-angle glaucoma, dementia, or control subjects.Methods: Protein-A eluates from plasma of 20 diabetic subjects having glaucoma or suspects and 34 age-matched controls were tested for effects on neurite outgrowth in rat pheochromocytoma PC12 cells or endothelial cell survival. The mechanism of the diabetic glaucoma autoantibodies’ neurite-inhibitory effect was investigated in co-incubations with the selective Rho kinase inhibitor Y27632 or the sulfated proteoglycan synthesis inhibitor sodium chlorate. Stored protein-A eluates from certain diabetic glaucoma or dementia subjects which contained long-lasting, highly stable cell inhibitory substances were characterized using mass spectrometry and amino acid sequencing.Results: Diabetic primary open angle glaucoma (POAG) or suspects (n = 20) or diabetic dementia (n = 3) autoantibodies caused significantly greater mean inhibition of neurite outgrowth in PC12 cells (p < 0.0001) compared to autoantibodies in control diabetic (n = 24) or non-diabetic (n = 10) subjects without glaucoma (p < 0.01). Neurite inhibition by the diabetic glaucoma autoantibodies was completely abolished by 10 μM concentrations of Y27632 (n = 4). It was substantially reduced by 30 mM concentrations of sodium chlorate (n = 4). Peak, long-lasting activity survived storage ×5 years at 0–4°C and was associated with a restricted subtype of Ig kappa light chain. Diabetic glaucoma or dementia autoantibodies (n = 5) caused contraction and process retraction in quiescent cerebral cortical astrocytes effects which were blocked by 5 μM concentrations of Y27632.Conclusion: These data suggest that autoantibodies in subsets of adult diabetes having POAG (glaucoma suspects) and/or dementia inhibit neurite outgrowth and promote a reactive astrocyte morphology by a mechanism which may involve activation of the RhoA/p160 ROCK signaling pathway.

Highlights

Glaucoma is a chronic neurodegenerative disorder affecting retinal ganglion cells (RGC) and is a leading cause of blindness worldwide (Quigley, 2011)
These data suggest that autoantibodies in subsets of adult diabetes having primary open angle glaucoma (POAG) and/or dementia inhibit neurite outgrowth and promote a reactive astrocyte morphology by a mechanism which may involve activation of the RhoA/p160 ROCK signaling pathway
We report that plasma IgG autoantibodies from diabetic POAG or suspects (n = 20) significantly inhibited neurite outgrowth in PC12 cells (p < 0.0001) compared to autoantibodies from diabetic (n = 24) or non-diabetic (n = 10) subjects without glaucoma

Summary

Introduction

Glaucoma is a chronic neurodegenerative disorder affecting retinal ganglion cells (RGC) and is a leading cause of blindness worldwide (Quigley, 2011). Glaucoma has been reported to increase in older adults with type 2 diabetes mellitus (Klein et al, 1994; Goldacre et al, 2012), and in certain populations having Alzheimer’s dementia (Tamura et al, 2006), the mechanisms for these associations are unclear. The aim of the present study was to test the hypothesis that autoantibodies having anti-endothelial and anti-neuronal effects increase in older adults with type 2 diabetes and primary open angle glaucoma (POAG). The diabetic neuropathy plasma IgG autoantibodies induced EC contraction, EC apoptosis, and inhibited neurite outgrowth through a mechanism involving activation of the Rho A/Rho kinase signaling pathway (Zimering and Pan, 2009; Zimering et al, 2011). The Rho A/Rho kinase signaling pathway is present in diverse cell types (neurons, astrocytes, and endothelial-like trabecular meshwork cells) implicated in the pathophysiology of glaucoma

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