Department of Medicine, Division of Rheumatology
Amino Acids, Peptides, and Proteins | Biological Phenomena, Cell Phenomena, and Immunity | Cell Biology | Eye Diseases | Nervous System | Neuroscience and Neurobiology | Ophthalmology
BACKGROUND: Glaucoma is a complex, multifactorial disease where apoptosis, microglia activation, and inflammation have been linked to the death of retinal ganglion cells (RGCs) and axon degeneration. We demonstrated previously that FasL-Fas signaling was required for axon degeneration and death of RGCs in chronic and inducible mouse models of glaucoma and that Fas activation triggered RGC apoptosis, glial activation, and inflammation. Here, we investigated whether targeting the Fas receptor with a small peptide antagonist, ONL1204, has anti-inflammatory and neuroprotective effects in a microbead-induced mouse model of glaucoma.
METHODS: Intracameral injection of microbeads was used to elevate intraocular pressure (IOP) in Fas-deficient (Fas(lpr)) mice and WT C57BL/6J mice that received an intravitreal injection of the Fas inhibitor, ONL1204 (2 mug/1 mul) (or vehicle only), on day 0 or day 7 after microbead injection. The IOP was monitored by rebound tonometry, and at 28 days post-microbead injection, Brn3a-stained RGCs and paraphenylenediamine (PPD)-stained axons were analyzed. The effects of ONL1204 on retinal microglia activation and the expression of inflammatory genes were analyzed by immunostaining of retinal flatmounts and quantitative PCR (qPCR).
RESULTS: Rebound tonometry showed equivalent elevation of IOP in all groups of microbead-injected mice. At 28 days post-microbead injection, the RGC and axon counts from microbead-injected Fas(lpr) mice were equivalent to saline-injected (no IOP elevation) controls. Treatment with ONL1204 also significantly reduced RGC death and loss of axons in microbead-injected WT mice when compared to vehicle-treated controls, even when administered after IOP elevation. Confocal analysis of Iba1-stained retinal flatmounts and qPCR demonstrated that ONL1204 also abrogated microglia activation and inhibited the induction of multiple genes implicated in glaucoma, including cytokines and chemokines (GFAP, Caspase-8, TNFalpha, IL-1beta, IL-6, IL-18, MIP-1alpha, MIP-1beta, MIP-2, MCPI, and IP10), components of the complement cascade (C3, C1Q), Toll-like receptor pathway (TLR4), and inflammasome pathway (NLRP3).
CONCLUSIONS: These results serve as proof-of-principal that the small peptide inhibitor of the Fas receptor, ONL1204, can provide robust neuroprotection in an inducible mouse model of glaucoma, even when administered after IOP elevation. Moreover, Fas signaling contributes to the pathogenesis of glaucoma through activation of both apoptotic and inflammatory pathways.
Apoptosis, Fas ligand, Fas receptor, Glaucoma, Immune privilege, Microglia, Neurodegeneration, Neuroinflammation, Neuroprotection, Retinal ganglion cell
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© The Author(s). 2019 Open Access: This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
DOI of Published Version
J Neuroinflammation. 2019 Sep 30;16(1):184. doi: 10.1186/s12974-019-1576-3. Link to article on publisher's site
Journal of neuroinflammation
Krishnan A, Kocab AJ, Zacks DN, Marshak-Rothstein A, Gregory-Ksander M. (2019). A small peptide antagonist of the Fas receptor inhibits neuroinflammation and prevents axon degeneration and retinal ganglion cell death in an inducible mouse model of glaucoma. Open Access Articles. https://doi.org/10.1186/s12974-019-1576-3. Retrieved from https://escholarship.umassmed.edu/oapubs/3987
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
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