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Siqi Li, Jiangyuan Gao, Jing Z Cui, Joanne A Matsubara; NLRP3 inflammasome contributes to retinal ganglion cell (RGC) death during glaucoma pathogenesis in DBA/2J mouse model.. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3790. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Glaucoma is a neurodegenerative disease. Neuroinflammation is an important factor contributing to RGC death during glaucoma pathogenesis. Evidence suggests that NLRP3 inflammasome activity is potentially associated with the change in intraocular pressure (IOP), which is speculated to trigger RGC death in glaucoma pathogenesis. The purpose of this study is to investigate whether NLRP3 inflammasome is activated by IOP elevation and contributes to RGC death in a glaucoma (DBA/2J) mouse model.
DBA/2J mice were divided into two age groups and sacrificed at 3- or 9-months (m) of age. IOP was measured before sacrifice. Left eyes were fixed for paraffin embedding or retina wholemount preparation; right eyes were fresh frozen and homogenized for protein extraction. To investigate NLRP3 inflammasome activity, immunohistochemistry of NLRP3 and IL-1β were processed on paraffin sections and the caspase-1 cleavage level in mouse whole eye protein lysates was analyzed by western blot. RGC loss was quantified on retina wholemounts by Brn3a staining.
The IOP of 9m DBA/2J mice (12.34±1.73mmHg) is significantly higher than that in 3m mice (9.84±0.56mmHg) (p<0.01, Mean ± SEM). Concomitantly, our data also showed that 9m DBA/2J mice have significantly increased expression level of NLRP3 in peripheral and central RGC layer comparing to the corresponding regions in 3m DBA/2J mice with a fold change of 5.02 and 9.31 respectively (p<0.01). There was a trend towards upregulation in IL-1β expression level of 9m DBA/2J mice. The pro-caspase-1 expression level of 9m mice is lower than 3m DBA/2J mice, while cleaved caspase-1 expression level of 9m DBA/2J mice is more than 2.5-fold higher than younger mice.
In this study, we have discovered an upregulation of NLRP3 and IL-1β protein levels in RGC layer and enhanced caspase-1 cleavage in 9m DBA/2J mice compared to 3m ones. These findings parallel the measurements of elevated IOP, suggesting that NLRP3 inflammasome activation is associated with IOP-induced RGC death in this mouse model. Further experiments are needed to determine whether specific NLRP3 inflammasome inhibitors could prevent RGC loss in this glaucoma mouse model.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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