Glaucoma is a major cause of blindness worldwide and is characterized by a series of pathological changes to optic nerve head astrocytes and retinal ganglion cells that eventually lead to vision loss. While the biggest risk factor for cell injury is elevated intraocular pressure (IOP), proinflammatory cytokines also contribute to the chronic disease. The mechanisms connecting physical strain to the cytokine response are unclear, however. This proposal is based upon the novel hypothesis that extracellular ATP links mechanical strain to the enhanced cytokine response in glaucoma. In particular, the mechanosensitive release of ATP through pannexin channels on optic nerve astrocytes can autostimulate adjacent P2X7 receptors, upregulating cytokine expression on a molecular level and activating cytokine release through both the inflammasome and classic release pathways. Using in vivo models of elevated IOP and in vitro models of cell stretch, we will demonstrate the mechanisms linking strain and inflammation and identify points of intervention.
Aim 1 will confirm the involvement of cytokines IL-1? and IL-6 in models of chronic and acute glaucoma. The time course of cytokine activation will be determined and the relative contribution of proinflammatory signals in older animals will be assessed. The contribution of pannexin and P2X7 channels will be explored on a molecular level with knockout mice, and on a pharmacological level with channel blockers;the ability of antagonists to reduce inflammasome activation may identify new treatments.
In Aim 2, the mechanisms connecting mechanical strain, ATP and cytokines will be confirmed in optic nerve head astrocytes while the effects of inflammasome product IL-1? on retinal ganglion cell health will be determined. In summary, this proposal will demonstrate that purinergic signaling links elevated IOP with the enhanced inflammatory response in astrocytes and pathology in retinal ganglion cells. This novel approach will advance our understanding of the disease on a mechanistic level while identifying possible new targets for intervention.

Public Health Relevance

Glaucoma is a major cause of blindness. This project will investigate how the increased intraocular pressure of glaucoma leads to increased inflammatory signaling in the posterior eye, determine if this link increases with age, and test the ability of drugs to prevent this response.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
2R01EY015537-08A1
Application #
8651585
Study Section
(DPVS)
Program Officer
Chin, Hemin R
Project Start
2004-04-01
Project End
2018-01-31
Budget Start
2014-02-01
Budget End
2015-01-31
Support Year
8
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Anatomy/Cell Biology
Type
Schools of Dentistry/Oral Hygn
DUNS #
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
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Ventura, Ana Lucia Marques; Dos Santos-Rodrigues, Alexandre; Mitchell, Claire H et al. (2018) Purinergic signaling in the retina: From development to disease. Brain Res Bull :
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Albalawi, Farraj; Lu, Wennan; Beckel, Jonathan M et al. (2017) The P2X7 Receptor Primes IL-1? and the NLRP3 Inflammasome in Astrocytes Exposed to Mechanical Strain. Front Cell Neurosci 11:227
Lu, Wennan; Albalawi, Farraj; Beckel, Jonathan M et al. (2017) The P2X7 receptor links mechanical strain to cytokine IL-6 up-regulation and release in neurons and astrocytes. J Neurochem 141:436-448
Workman, Alan D; Carey, Ryan M; Chen, Bei et al. (2017) CALHM1-Mediated ATP Release and Ciliary Beat Frequency Modulation in Nasal Epithelial Cells. Sci Rep 7:6687
Mitchell, Claire H; Stamer, W Daniel (2016) Dedication of Special Issue on Purinergic Regulation in the Eye to Mortimer M. Civan. J Ocul Pharmacol Ther 32:484

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