Inflammatory signals from microglia modulate laser-induced choroidal neovascularization in mice via SOCS3

Abstract

Purpose : Choroidal neovascularization (CNV) occurs in only 10% of age-related macular degeneration (AMD) patients, but it accounts for up to 90% of vision loss associated with AMD. Inflammation and immune dysregulation had been reported to link to CNV both clinically and experimentally and immune cells especially myeloid origin is attracted to and control experimental CNV in part through the JAK2/STAT3/SOCS3 pathway. The purpose of this study was to determine whether overexpression of SOCS3 in immune cells of myeloid origin suppresses the development of laser-induced CNV in mice.

Methods : Myeloid-specific SOCS3 loss-of-function (Socs3^cKO), gain-of-function (Socs3^cKI), and controls were used for laser-induced CNV. A SOCS3 agonist and control were injected intraperitoneally into 8-week-old C57BL/6J mice. At day (d) 6 post-laser, fundus fluorescein angiography (FFA) was performed at the intervals of 1, 5 and 10 minutes post intraperitoneal fluorescein injection to evaluate the levels of vascular leakage from CNV lesions. The fluorescent intensity was graded using ImageJ and recorded as an indicator of CNV vascular leakage. At d7 post laser, eyes were collected and fixed with 4% paraformaldehyde, and the retinal pigment epithelium (RPE)/choroid/sclera complexes were dissected and permeabilized. The areas of CNV lesions were quantified in a masked fashion. Microglia recruitment was assessed via IHC and FACS assays.

Results : Myeloid specific deletion of SOCS3 significantly increased laser-induced CNV (p<0.001, n=40-46 lesions from 10 mice/group), and myeloid specific overexpression of SOCS3 dramatically reduced CNV (p<0.001, n=30 lesions from 8 mice/group). Pharmacologic treatment with a SOCS3 activator suppressed CNV in the laser-induced CNV model (p<0.001, n=45-50 lesions from 10-12 mice/group). Myeloid SOCS3 overexpression suppressed the mRNA expression of Il6, Il1b and Tnf (n=3 mice) in the laser-induced CNV model (Il6 and Tnf, p<0.01; Il1b, p<0.001). These data suggested that myeloid specific SOCS3 overexpression suppressed pathological NV in the laser-induced CNV model through modulating inflammatory signals.

Conclusions : Our results are consistent with our hypothesis that overexpression of myeloid SOCS3 suppresses the lesion size of laser-induced CNV. Additionally, the inflammatory mediators from microglia with significantly altered expression in laser-induced CNV mice were modulated by SOCS3.

This is a 2020 ARVO Annual Meeting abstract.