Inhibition of NLRP3 inflammasomes regulates monocyte/macrophage recruitment in choroidal neovascularization

Abstract

Purpose : Age-related macular degeneration (AMD) is a vision threatening condition affecting older adults accounting for most blindness cases in developed countries. Currently, wet AMD is managed by intravitreal administration of anti-VEGF drugs. However, about 50% of AMD patients exhibit an incomplete response to anti-VEGF drugs. Thus, there is an urgent need for effective treatment options for AMD patients. NLRP3 inflammasomes are associated with macrophages that infiltrate into the CNV lesions. The purpose of this research is to characterize the role of NLRP3 inflammasomes in macrophages recruitment in choroidal neovascularization.

Methods : We have used Ccr2^RFPCx3cr1^GFP dual-reporter mice to characterize migration of Ccr2^RFP positive macrophages and Cx3cr1^GFP positive microglia in the mouse model of laser-induced choroidal neovascularization (LCNV). MCC950 was used as selective inhibitor of NLRP3 in Ccr2^RFPCx3cr1^GFP dual-reporter mice. In addition, we have used NLRP3 deficient mice (Nlrp3^tm1Bhk/J) to characterize the role of NLRP3 inflammasomes in LCNV progression compared to controls.

Results : Ex vivo imaging of choroidal tissues from Ccr2^RFPCx3cr1^GFP dual-reporter mice showed, LCNV lesions contain RFP positive monocytes/macrophages (about 15% of the total LCNV volume), GFP positive microglia (about 20%); and ICAM-2 positive cells (about 65%). The immunofluorescence staining shows that NLRP3 inflammasomes are associated with LCNV lesions and inhibition of NLRP3 inflammasomes using MCC950 significantly reduced the volume of Ccr2^RFP positive macrophages. Cx3cr1^GFP positive microglia remained the same after NLRP3 inhibition, but total CNV volume increased. In NLRP3 deficient mice, volume of LCNV lesions were significantly larger compared to age-matched controls LCNV animals, suggesting that NLRP3 inhibition may contribute to proliferation of choroidal endothelial cells, contributing to CNV lesions.

Conclusions : NLRP3 inflammasomes may contribute to the migration of circulating monocyte/macrophages to CNV lesions in response to inflammation. These migratory cells may have protective roles in CNV development and progression.

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