Abstract
Purpose :
Inflammasomes are large multiprotein complexes that serve as innate immune sensors of danger-associated signals, activating pro-inflammatory cytokines, and triggering pyroptotic cell death. Inflammasome forming proteins, including NLR family pyrin domain containing 3 (NLRP3), have been implicated in many ocular pathologies including glaucoma. Retinal ischemia/reperfusion (I/R) induced by an acute increase of intraocular pressure (IOP) is a well-established animal model of acute angle-closure glaucoma. While this model is associated with neurodegeneration and cytokine release, the molecular basis including inflammasome contribution remains incompletely understood. Here we tested the hypothesis that NLRP3 mediates neurodegeneration in acute IOP retinal I/R injury.
Methods :
Retinal ischemia was induced by raising the IOP to 110mm Hg for 60 minutes in the right eye of wild type (WT) mice, NLRP3-/- mice, and WT mice systemically treated with MCC950 (20mg/kg), a selective small molecule NLRP3 inhibitor. Controls included the left eye maintained at normal IOP and eyes from naïve mice. At 24 and 48 hours post cannulation, mice were euthanized and eyes were collected. Vitreous samples were analyzed for IL-1β by ELISA. RGC density and microglia morphology were assessed in retinal whole mounts stained with anti-Brn3a (RGC marker) and anti-TMEM119 (microglia marker) antibodies, respectively.
Results :
At 24 hours post cannulation, cleaved IL-1β was significantly increased in the vitreous of cannulated WT eyes as compared to non-cannulated controls. This increase in cleaved IL-1β was completely abrogated in cannulated NLRP3 deficient mice. At 48 hours post cannulation, RGC density was significantly reduced in cannulated WT eyes as compared to non-cannulated controls. However, no significant loss of RGCs was observed in cannulated eyes of NLRP3-/- mice and cannulated eyes of WT mice treated with MCC950, when compared to non-cannulated controls. Preservation of RGCs coincided with reduced microglia activation as determined by cellular morphology.
Conclusions :
Through genetic and pharmacological approaches, we demonstrate inhibition of the NLRP3 inflammasome is neuroprotective in a model of IOP-induced I/R injury, identifying the NLRP3 inflammasome as a therapeutic target for the treatment of acute angle-closure glaucoma.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.