Abstract
Purpose :
We have presented immunomodulatory and neuroprotective outcomes of inhibited glial NF-κB by cre/lox-based IκKβ deletion in experimental glaucoma. This extension study aimed to analyze transgenic effects on bioenergetics profile of astroglia.
Methods :
Intraocular pressure elevation was induced in GFAP/IκKβ (crossbreds of IκKβ-f/f and GFAP-CreERT2) and WT (C57BL/6J) mice by anterior chamber microbead/viscoelastic injections. Transgenic effects on neuron survival and function (by RGC/axon counts and PERG) and glial inflammatory phenotype (by glial morphology/GFAP/Iba labeling, and cytokine/chemokine profiles) were determined at 12 weeks of ocular hypertension. In addition, we isolated retina and optic nerve head astroglia (by immunomagnetic cell selection) for isotope labeling-based quantitative LC-MS/MS analysis. Proteomic data were validated by immunoblotting and immunohistochemistry.
Results :
Parallel to increased neuron counts and PERG amplitude (over 40% protection), and lower ELISA titers of pro-inflammatory cytokines (~four-fold decrease in TNF-α and IFN-γ), proteomics analysis detected (with false discovery rate of <1%) significant alterations in astroglial protein expression (p<0.05) in GFAP/IκKβ versus WT ocular hypertensive mice (matched for the IOP-time integral). Based on IPA analysis of high throughput datasets, transgenic effects included over two-fold down-regulation of various molecules linked to inflammation signaling. Deletion of astroglial IκKβ also resulted in recovery of glaucoma-related down-regulation of mitochondrial oxidative phosphorylation. In addition, oxidoreductase enzymes (LDHA, LDHB) needed for conversion of glycolytically-derived pyruvate to lactate, and molecules needed for monocarboxylate shuttling to neurons (MCT1, MCT4) were up-regulated. Up-regulated astroglial proteins in transgenic ocular hypertensive samples also included glycogenesis enzymes (glycogenin, glycogen synthase).
Conclusions :
Astroglia-targeted immunomodulation in experimental glaucoma presents anti-inflammatory and neuroprotective outcomes in RGC somas and axons. By decreasing the energy need and changing the bioenergetic profile of glial cells, neuroprotective outcomes of immunomodulation may also include bioenergetic consequences that may promote improved glial neurosupport by increased supplement of energy substrates to relieve neuronal energy insufficiency.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.