SOCS3 in myeloid cells regulates neovascularization in oxygen-induced retinopathy

Abstract

Purpose : Neovascularization is the leading cause of vision loss in retinopathy of prematurity (ROP), yet there are still no adequate treatments to prevent it. Inflammation and myeloid cells are involved in neovascularization, however, the detailed mechanisms of neovascularization in ROP remain unknown. Expression of the suppressor of cytokine signaling 3 (SOCS3) can be increased in an ROP mouse model, oxygen-induced retinopathy (OIR) and SOCS3 inhibited inflammation and growth factor signaling. Knowing this, we sought to investigate the functions of SOCS3 in myeloid cells using the OIR mouse model.

Methods : LysM-Cre mice were crossed with Socs3 flox/flox (Socs3 ^f/f) mice to generate Socs3 loss-of-function mice (Socs3^cKO). Mouse pups with their nursing female mice were exposed to 75% oxygen from postnatal day P7 to P12, and then returned to normal air until P17. Retinas were collected at P7, P12, P17. These retinas were staining with fluorescent Isolectin B4 (Invitrogen), and flat mounted. Real-time PCR, western blot and immunohistochemistry were used to analyze gene expression and protein localization. Confocal and fundus fluorescein angiography were used to identify phenotypes. FACS was used for immune cell population assay and immune cell isolation. Results are presented as mean ± SEM and were compared using the 2-tailed unpaired t-test. Statistical analyses were performed with GraphPad Prism.

Results : The protein level of SOCS3 in whole retinas was significantly increased in the OIR model. Mice with SOCS3 deficiency in myeloid cells had a substantial increase in pathological retinal neovascularization in response to OIR, whereas overexpression of SOCS3 in myeloid cells prevented pathological retinal neovascularization in response to OIR. However, both overexpression and knockout of SOCS3 in myeloid cells did not change the vaso-obliterated retinal areas in OIR mice. The mRNA expression of macrophage markers (Iba1, F4/80 and CD11b) and inflammatory cytokine (Il6, Il1b and Tnf) was increased in mice with Socs3 deficiency in myeloid cells.

Conclusions : Through the OIR model, it can be seen that SOCS3 in myeloid cells is involved in retinal neovascularization. Socs3 deficiency in myeloid cells increased pathological neovascularization, while overexpression of SOCS3 in myeloid cells prevented neovascularization. Manipulating SOCS3 expression in myeloid cells may provide a new way to cure neovascularization in retinas.

This is a 2020 ARVO Annual Meeting abstract.