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

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.

Diabetes Autoantibodies Mediate Neural- and Endothelial Cell- Inhibitory Effects Via 5-Hydroxytryptamine- 2 Receptor Coupled to Phospholipase C/Inositol Triphosphate/Ca2+ Pathway

“…IP3 causes release of Ca2+ from intracellular stores, the latter plays a role in the activation of protein kinase C. In the current study, specific inhibitors of phospholipase C (PLC-γ), IP3R and an intracellular calcium chelator each nearly or completely prevented acute autoantibody-induced neurite retraction. The selective RhoA/ ROCK inhibitor Y27632 (10 µM) also completed prevented acute neurite retraction consistent with results in previous studies [5,6,7,8,9]. The precise mechanism linking PLC/IP3R/ Ca2+ activation with RhoA/ROCK-signaling in N2A cells is not clear, however, evidence from other laboratories indicates that ROCK activation can occur through the coordinated action(s) of activated Gαq/11 and beta (β) -arrestin-1 [19].…”

“…atrial fibrillation, obstructive sleep apnea) in which neurotoxic plasma autoantibodies were present at increased levels compared to control diabetic patients [8]. [9]. Obstr (uctive); Incr (eased) compared to Control diabetes populations lacking this complication; stim (ulate); NT-not tested; N2A mouse Neuroblastoma cell line; rtrct (retraction), cntr (contraction); short (ening), depol (arization), DG dentate gyrus, NPC-neural progenitor cell, " i.e.…”

Increased Neuronal Depolarization Evoked by Autoantibodies in Diabetic Obstructive Sleep Apnea: Role for Inflammatory Protease(s) in Generation of Neurotoxic Immunoglobulin Fragment

“…glaucoma or dementia [9]. In the present study, storage (9-60 months at 0-4 ° C) (n = 5) unmasked significant EC inhibitory activity preferentially in diabetic OSA protein-A-eluates compared to the stored protein-A-eluates of diabetes without OSA (n = 17) (Table 2).…”

Characterizing the “POAGome”: A bioinformatics-driven approach to primary open-angle glaucoma

“…In this network, both VAV2 and VAV3 are shown to interact with TCR (T-cell receptor) and RHOG (Ras homolog family member G). Both VAV2 and VAV3 activated RHOG, which has been shown to be an important regulator of neurite outgrowth, a process that has is hindered in some POAG patients (Katoh et al, 2000; Zimering et al, 2013). VAV3 has been shown to stimulate IL-2 expression, making these proteins potentially important inflammatory mediators (Zakaria et al, 2004).…”