Critical pathogenic events underlying progression of neurodegeneration in glaucoma

Calkins, David J.

doi:10.1016/j.preteyeres.2012.07.001

Cited by 266 publications

(324 citation statements)

References 196 publications

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“…There are still many unanswered questions about the initiation factors, mechanism(s), and timing of axon injury in numerous diseases 77, 78, 79, 80, 81, 82, 83, 84. Axonopathy is ultimately driven by a confluence of factors and occurs via several intermediate and potentially reversible stages that eventually lead to irrevocable axonal degeneration 85.…”

Section: Discussionmentioning

confidence: 99%

Retrograde interferon‐gamma signaling induces major histocompatibility class I expression in human‐induced pluripotent stem cell‐derived neurons

Clarkson

Patel

LaFrance‐Corey

et al. 2017

Ann Clin Transl Neurol

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ObjectiveInjury‐associated axon‐intrinsic signals are thought to underlie pathogenesis and progression in many neuroinflammatory and neurodegenerative diseases, including multiple sclerosis (MS). Retrograde interferon gamma (IFN γ) signals are known to induce expression of major histocompatibility class I (MHC I) genes in murine axons, thereby increasing the susceptibility of these axons to attack by antigen‐specific CD8+ T cells. We sought to determine whether the same is true in human neurons.MethodsA novel microisolation chamber design was used to physically isolate and manipulate axons from human skin fibroblast‐derived induced pluripotent stem cell (iPSC)‐derived neuron‐enriched neural aggregates. Fluorescent retrobeads were used to assess the fraction of neurons with projections to the distal chamber. Axons were treated with IFN γ for 72 h and expression of MHC class I and antigen presentation genes were evaluated by RT‐PCR and immunofluorescence.ResultsHuman iPSC‐derived neural stem cells maintained as 3D aggregate cultures in the cell body chamber of polymer microisolation chambers extended dense axonal projections into the fluidically isolated distal chamber. Treatment of these axons with IFN γ resulted in upregulation of MHC class I and antigen processing genes in the neuron cell bodies. IFN γ‐induced MHC class I molecules were also anterogradely transported into the distal axon.InterpretationThese results provide conclusive evidence that human axons are competent to express MHC class I molecules, suggesting that inflammatory factors enriched in demyelinated lesions may render axons vulnerable to attack by autoreactive CD8+ T cells in patients with MS. Future work will be aimed at identifying pathogenic anti‐axonal T cells in these patients.

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Section: Discussionmentioning

confidence: 99%

Retrograde interferon‐gamma signaling induces major histocompatibility class I expression in human‐induced pluripotent stem cell‐derived neurons

Clarkson

Patel

LaFrance‐Corey

et al. 2017

Ann Clin Transl Neurol

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“…In many neurodegenerative diseases in the CNS, including glaucoma, there is an initial loss of vulnerable neurons related directly to the primary insult, followed by a progressive, secondary cell loss (7,8). There is now strong evidence that intercellular communication through gap junctions (GJs) plays a major role in secondary or so-called bystander cell death (9)(10)(11).…”

Section: Introductionmentioning

confidence: 99%

Targeting neuronal gap junctions in mouse retina offers neuroprotection in glaucoma

Akopian¹,

Kumar²,

Ramakrishnan³

et al. 2017

Journal of Clinical Investigation

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The progressive death of retinal ganglion cells and resulting visual deficits are hallmarks of glaucoma, but the underlying mechanisms remain unclear. In many neurodegenerative diseases, cell death induced by primary insult is followed by a wave of secondary loss. Gap junctions (GJs), intercellular channels composed of subunit connexins, can play a major role in secondary cell death by forming conduits through which toxic molecules from dying cells pass to and injure coupled neighbors. Here we have shown that pharmacological blockade of GJs or genetic ablation of connexin 36 (Cx36) subunits, which are highly expressed by retinal neurons, markedly reduced loss of neurons and optic nerve axons in a mouse model of glaucoma. Further, functional parameters that are negatively affected in glaucoma, including the electroretinogram, visual evoked potential, visual spatial acuity, and contrast sensitivity, were maintained at control levels when Cx36 was ablated. Neuronal GJs may thus represent potential therapeutic targets to prevent the progressive neurodegeneration and visual impairment associated with glaucoma.

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“…Given that the progressive RGC injury occurring in glaucoma is characterized by a multifactorial pathology putatively involving a host of excitotoxic, inflammatory, immune, vascular, biomechanical, and other factors [58][59][60], and that the mechanisms dictating RGC soma and RGC axon loss may be quite distinct [61][62][63], the epigenetic changes induced by RH-Post will likely be extensive in order to account for the magnitude of the protection achieved. It is also worth noting that, although exposures to intermittent systemic hypoxia may not ultimately be adopted as a clinical treatment for glaucoma patients, this very stimulus has established a strong record for protection against a variety of acute and chronic diseases in the CNS [27][28][29][30][64][65][66][67], and other tissues [68][69][70], and may not be easily mimicked by a pharmacologic, monotherapy approach.…”

Section: Discussionmentioning

confidence: 99%

Enhanced Retinal Ganglion Cell Survival in Glaucoma by Hypoxic Postconditioning After Disease Onset

et al. 2015

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The neuroprotective efficacy of adaptive epigenetics, wherein beneficial gene expression changes are induced by nonharmful "conditioning" stimuli, is now well established in several acute, preclinical central nervous system injury models. Recently, in a mouse model of glaucoma, we demonstrated retinal ganglion cell (RGC) protection by repetitively "preconditioning" with hypoxia prior to disease onset, indicating an epigenetic approach may also yield benefits in chronic neurodegenerative disease. Herein, we determined whether presenting the repetitive hypoxic stimulus after disease initiation [repetitive hypoxic "postconditioning" (RHPost)] could afford similar functional and morphologic protection against glaucomatous RGC injury. Chronic elevations in intraocular pressure (IOP) were induced unilaterally in adult male C57BL/6 mice by episcleral vein ligation. Mice were randomized to an RH-Post [1 h of systemic hypoxia (11 % oxygen) every other day, starting 4 days after IOP elevation] or an untreated control group. After 3 weeks of experimental glaucoma, the 21-27 % reduction and 5-25 % prolongation in flash visual-evoked potential amplitudes and latencies, respectively, and the 30 % impairment in visual acuity were robustly improved in RH-Post-treated mice, as was the 17 % loss in RGC soma number and 20 % reduction in axon integrity. These protective effects were observed without RH-Post affecting IOP. The present findings demonstrate that functional and morphologic protection of RGCs can be realized by stimulating epigenetic responses during the early stages of disease, and thus constitute a new conceptual approach to glaucoma therapeutics.

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Critical pathogenic events underlying progression of neurodegeneration in glaucoma

Cited by 266 publications

References 196 publications

Retrograde interferon‐gamma signaling induces major histocompatibility class I expression in human‐induced pluripotent stem cell‐derived neurons

Retrograde interferon‐gamma signaling induces major histocompatibility class I expression in human‐induced pluripotent stem cell‐derived neurons

Targeting neuronal gap junctions in mouse retina offers neuroprotection in glaucoma

Enhanced Retinal Ganglion Cell Survival in Glaucoma by Hypoxic Postconditioning After Disease Onset

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