Glaucoma is an age-related disease that blinds through the degeneration of retinal ganglion cells (RGCs) and their axons in the optic nerve. By 2020, 80 million people will suffer from the disease, making it the leading cause of irreversible blindness. While age is the leading risk factor, elevated intraocular pressure (IOP) remains the primary treatable factor. Elevated IOP challenges RGC survival directly, but also indirectly by affecting signals from other other cell types. Interleukin-6 is an inflammatory cytokine released by glial cells that we have shown can be neuroprotective for isolated RGCs under pressure (Sappington et al., 2006). However, the effectiveness of IL-6 as a potential therapeutic intervention for glaucoma is likely to depend upon age, IOP and the physiological state of the RGC. The purpose of this proposal is to determine the impact and therapeutic relevance of IL-6 for RGCs challenged by age and elevated IOP in vivo. Using two mouse models of glaucoma, we will determine whether glial cells are a primary source of IL-6 and how production of IL-6 relates to 1) receptivity of RGCs to IL-6 and 2) function and survival of RGCs. To determine directly the influence of the IL-6 pathway on RGC survival, we will manipulate expression or activity of IL-6 and its receptor IL-6R in both models. We will utilize the DBA/2 mouse, a chronic model of ocular hypertension, and an acute model we have developed that uses microbeads to occlude aqueous flow and elevate IOP. As a function of age and IOP in these models, we will quantify cell type-specific expression and localization of IL-6 and IL-6R. We will correlate these data with the decline of RGC function and progression of degeneration. For assessment of RGC degeneration, we will use morphometric techniques to quantify changes in RGC soma density in retina and changes in axon caliber and density in the optic nerve. To assess RGC function, we will quantify anterograde and retrograde axonal transport using active-uptake tracers and ionic activity using and manganese-enhanced magnetic resonance imaging. Data regarding IL-6 signaling and RGC pathology will serve to identify a therapeutic window(s) for manipulation of the IL-6 system in each model using loss and gain of function studies. For loss of function studies, we will utilize a commercially-available IL-6 knockout mouse and antibody therapy directed at neutralization of IL-6. For gain of function studies, we will utilize a commercially-available IL-6 overexpression mouse, recombinant IL-6 therapy and antibody therapy directed at activation of IL-6R. Completion of these aims will provide insight into many key components of IL-6 signaling in glaucoma: 1) the levels and pattern of IL-6 expression: 2) cell type-specific expression of IL-6 and IL6-R, and 3) how IL-6 signaling influences RGC survival and function during disease progression.

Public Health Relevance

Glaucoma is the leading cause of irreversible blindness worldwide, involving the death of retinal ganglion cells (RGCs) and an association with elevated IOP. Elevated IOP challenges RGC survival directly, but also indirectly by affecting signals from other cells that could serve a protective role. We propose a series of studies to examine the potential of the inflammatory cytokine interleukin-6 as a therapeutic target to rescue RGCs in glaucoma.

National Institute of Health (NIH)
National Eye Institute (NEI)
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Anterior Eye Disease Study Section (AED)
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Chin, Hemin R
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Vanderbilt University Medical Center
Schools of Medicine
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Duncan, D'Anne S; Weiner, Rebecca L; Weitlauf, Carl et al. (2018) Ccl5 Mediates Proper Wiring of Feedforward and Lateral Inhibition Pathways in the Inner Retina. Front Neurosci 12:702
Wareham, Lauren K; Buys, Emmanuel S; Sappington, Rebecca M (2018) The nitric oxide-guanylate cyclase pathway and glaucoma. Nitric Oxide 77:75-87
Echevarria, Franklin D; Formichella, Cathryn R; Sappington, Rebecca M (2017) Interleukin-6 Deficiency Attenuates Retinal Ganglion Cell Axonopathy and Glaucoma-Related Vision Loss. Front Neurosci 11:318
Duncan, D'Anne S; McLaughlin, William M; Vasilakes, Noah et al. (2017) Constitutive and Stress-induced Expression of CCL5 Machinery in Rodent Retina. J Clin Cell Immunol 8:
Bond, Wesley S; Hines-Beard, Jessica; GoldenMerry, YPaul L et al. (2016) Virus-mediated EpoR76E Therapy Slows Optic Nerve Axonopathy in Experimental Glaucoma. Mol Ther 24:230-239
Echevarria, Franklin D; Rickman, Abigayle E; Sappington, Rebecca M (2016) Interleukin-6: A Constitutive Modulator of Glycoprotein 130, Neuroinflammatory and Cell Survival Signaling in Retina. J Clin Cell Immunol 7:
Lee, Sean J; Duncan, D'Anne S; Echevarria, Franklin D et al. (2015) Pressure-Induced Alterations in PEDF and PEDF-R Expression: Implications for Neuroprotective Signaling in Glaucoma. J Clin Exp Ophthalmol 6:
Dodson, Kirsten H; Echevarria, Franklin D; Li, Deyu et al. (2015) Retina-on-a-chip: a microfluidic platform for point access signaling studies. Biomed Microdevices 17:114
Formichella, Cathryn R; Abella, Simone K; Sims, Stephanie M et al. (2014) Astrocyte Reactivity: A Biomarker for Retinal Ganglion Cell Health in Retinal Neurodegeneration. J Clin Cell Immunol 5:
Echevarria, Fd; Walker, Cc; Abella, Sk et al. (2013) Stressor-dependent Alterations in Glycoprotein 130: Implications for Glial Cell Reactivity, Cytokine Signaling and Ganglion Cell Health in Glaucoma. J Clin Exp Ophthalmol 4:

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