Nucleoside reverse transcriptase inhibitors attenuate amyloid-beta-induced retinal pigment epithelium degeneration

Abstract

Purpose : Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly and is projected to afflict up to 200 million people worldwide by the year 2020; it is untreatable in the majority of cases. Recently studies from multiple groups have implicated NLRP3 inflammasome activation in AMD pathogenesis. Nucleoside reverse transcriptase inhibitors (NRTIs) are mainstay therapeutics for HIV that block retrovirus replication. Recently, we made a surprising discovery that NRTIs as a class inhibit NLRP3 inflammasome activation. Amyloid-beta (Aβ) is a drusen component found in AMD eyes and it is reported to induce upregulation of NLRP3, IL-1β, and IL-18 in mouse models. Therefore, we hypothesized that NRTIs block inflammasome activation and RPE cell death in cell culture and in Aβ-induced animal model of dry AMD.

Methods : For the mouse model of dry AMD, RPE degeneration was induced by subretinal injection of fibrillar Aβ_1-40. Twice daily intraperitoneal administration of NRTI lamivudine (3TC) (75 mg/kg/day) in wild-type C57BL6/J mice was performed for one week after fibrillar Aβ_1-40 administration. RPE degeneration was assessed by fundus photography and ZO-1 staining of RPE flat mounts. For cell culture, primary human RPE cells were maintained in DMEM supplemented with 10% FBS and antibiotics. Stimulation with fibrillar Aβ_1-40 was achieved by supplementing the culture medium for 24 hr. Cells were treated with NRTI lamivudine (3TC). NLRP3 inflammasome activation was monitored by western blot for Caspase-1.

Results : NRTI lamivudine (3TC) blocked RPE cell death and inflammasome activation induced by fibrillar Aβ_1-40. Intraperitoneal administration of the NRTI lamivudine, at a similar equivalent dose typically administered in humans, prevented RPE degeneration in the Aβ_1-40-induced mouse model of dry AMD.

Conclusions : We have identified that the novel anti-inflammatory action of NRTIs blocks Aβ-induced NLRP3 inflammasome activation, and demonstrated their in vivo ability to prevent RPE cell death in a mouse model of dry AMD.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.