Photoreceptors inhibit pathological retinal angiogenesis through transcriptional regulation of Adam17 via c-Fos.

Pathological retinal angiogenesis profoundly impacts visual function in vascular eye diseases, such as retinopathy of prematurity (ROP) in preterm infants and age-related macular degeneration in the elderly. While the involvement of photoreceptors in these diseases is recognized, the underlying mechanisms remain unclear. This study delved into the pivotal role of photoreceptors in regulating abnormal retinal blood vessel growth using an oxygen-induced retinopathy (OIR) mouse model through the c-Fos/A disintegrin and metalloprotease 17 (Adam17) axis. Our findings revealed a significant induction of c-Fos expression in rod photoreceptors, and c-Fos depletion in these cells inhibited pathological neovascularization and reduced blood vessel leakage in the OIR mouse model. Mechanistically, c-Fos directly regulated the transcription of Adam17 a shedding protease responsible for the production of bioactive molecules involved in inflammation, angiogenesis, and cell adhesion and migration. Furthermore, we demonstrated the therapeutic potential by using an adeno-associated virus carrying a rod photoreceptor-specific short hairpin RNA against c-fos which effectively mitigated abnormal retinal blood vessel overgrowth, restored retinal thickness, and improved electroretinographic (ERG) responses. In conclusion, this study highlights the significance of photoreceptor c-Fos in ROP pathology, offering a novel perspective for the treatment of this disease.

SOCS3 regulates pathological retinal angiogenesis through modulating SPP1 expression in microglia and macrophages.

Pathological ocular angiogenesis has long been associated with myeloid cell activation. However, the precise cellular and molecular mechanisms governing the intricate crosstalk between the immune system and vascular changes during ocular neovascularization formation remain elusive. In this study, we demonstrated that the absence of the suppressor of cytokine signaling 3 (SOCS3) in myeloid cells led to a substantial accumulation of microglia and macrophage subsets during the neovascularization process. Our single-cell RNA sequencing data analysis revealed a remarkable increase in the expression of the secreted phosphoprotein 1 (Spp1) gene within these microglia and macrophages, identifying subsets of Spp1-expressing microglia and macrophages during neovascularization formation in angiogenesis mouse models. Notably, the number of Spp1-expressing microglia and macrophages exhibited further elevation during neovascularization in mice lacking myeloid SOCS3. Moreover, our investigation unveiled the Spp1 gene as a direct transcriptional target gene of signal transducer and activator of transcription 3. Importantly, pharmaceutical activation of SOCS3 or blocking of SPP1 resulted in a significant reduction in pathological neovascularization. In conclusion, our study highlights the pivotal role of the SOCS3/STAT3/SPP1 axis in the regulation of pathological retinal angiogenesis.

Ocular Vascular Diseases: From Retinal Immune Privilege to Inflammation.

The eye is an immune privileged tissue that insulates the visual system from local and systemic immune provocation to preserve homeostatic functions of highly specialized retinal neural cells. If immune privilege is breached, immune stimuli will invade the eye and subsequently trigger acute inflammatory responses. Local resident microglia become active and release numerous immunological factors to protect the integrity of retinal neural cells. Although acute inflammatory responses are necessary to control and eradicate insults to the eye, chronic inflammation can cause retinal tissue damage and cell dysfunction, leading to ocular disease and vision loss. In this review, we summarized features of immune privilege in the retina and the key inflammatory responses, factors, and intracellular pathways activated when retinal immune privilege fails, as well as a highlight of the recent clinical and research advances in ocular immunity and ocular vascular diseases including retinopathy of prematurity, age-related macular degeneration, and diabetic retinopathy.

Myeloid lineage contributes to pathological choroidal neovascularization formation via SOCS3.

BACKGROUND: Pathological neovascularization in neovascular age-related macular degeneration (nAMD) is the leading cause of vision loss in the elderly. Increasing evidence shows that cells of myeloid lineage play important roles in controlling pathological endothelium formation. Suppressor of cytokine signaling 3 (SOCS3) pathway has been linked to neovascularization. METHODS: We utilised a laser-induced choroidal neovascularization (CNV) mouse model to investigate the neovascular aspect of human AMD. In several cell lineage reporter mice, bone marrow chimeric mice and Socs3 loss-of-function (knockout) and gain-of-function (overexpression) mice, immunohistochemistry, confocal, and choroidal explant co-culture with bone marrow-derived macrophage medium were used to study the mechanisms underlying pathological CNV formation via myeloid SOCS3. FINDINGS: SOCS3 was significantly induced in myeloid lineage cells, which were recruited into the CNV lesion area. Myeloid Socs3 overexpression inhibited laser-induced CNV, reduced myeloid lineage-derived macrophage/microglia recruitment onsite, and attenuated pro-inflammatory factor expression. Moreover, SOCS3 in myeloid regulated vascular sprouting ex vivo in choroid explants and SOCS3 agonist reduced in vivo CNV. INTERPRETATION: These findings suggest that myeloid lineage cells contributed to pathological CNV formation regulated by SOCS3. FUNDING: This project was funded by NIH/NEI (R01EY030140, R01EY029238), BrightFocus Foundation, American Health Assistance Foundation (AHAF), and Boston Children's Hospital Ophthalmology Foundation for YS and the National Institutes of Health/National Heart, Lung and Blood Institute (U01HL098166) for PZ.