Inflammasome activation exacerbates ganglion cell dysfunction and loss in ocular hypertension/glaucoma.

Abstract

Purpose : To determine molecular pathways facilitating retinal ganglion cell (RGC) dysfunction and death in response to ocular hypertension (OHT)-induced stress. In this study, we sought to establish the contribution of the inflammasome to RGC pathology in a mouse model of OHT-induced glaucoma.

Methods : Glaucomatous degeneration was induced by intracameral injection of the Ad5-MYOC vector that produced a chronic IOP elevation. Inflammasome activation was detected by interleukin (IL)-1β production assessed with sandwich ELISA, changes in casp1, pycard (ASC), nlrp1, and gsdmD gene expression, and protein accumulation using RT-PCR, Western blotting, and immunohistochemistry. Wild type and knockout mouse strains were used to determine the role of the inflammasome in ocular hypertension/glaucoma. Release of IL-1β, TNFa and CCL2 cytokines was assessed with assessed by SimplePlex technology. Changes in RGC functionality were assessed by PERG recordings; RGC loss was assessed at 8 wks post-OHT induction by counts in retina flat mounts.

Results : Activation of the inflammasome was present in the inner retina layers and co-localized with RGCs (identified with RBPMS antibody) in C57BL6 (WT) mice at 2-4 wks after glaucoma induction. PERG amplitude was subsequently reduced 55.8% in WT eyes with chronic OHT-induced glaucoma and RGC density in these animals declined 32.3±9.2 % in the central and 28.4±9.2 % in the peripheral retina at 6 wks post-OHT-induction. In contrast, mice deficient in key inflammasome complex proteins NLRP1, Casp1 and GsdmD did not produce statistically significant changes in PERG amplitude or RGC loss, averaging 0.7±11.2% increase in the central retina and no change in the peripheral retina of NLRP1-/- eyes; 7.3± 9.2% decrease in the central and 1.3 ±19.5 % increase in the peripheral retina of Casp1-/- eyes. Immunohistochemistry data in retinal cross-sections showed the absence of Casp1 and a reduction in GsdmD immunolabeling in RGCs in the knockout retinas with induced glaucoma.

Conclusions : Our results show a strong association between the elevation of IOP, inflammasome activation, and RGC pathology in the retina. Our knockout mouse data have revealed a key role of the inflammasome in driving RGC dysfunction and cell death, suggesting that inhibitors of the inflammasome could protect vision loss in human glaucoma.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.