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Ayumi Ouchi, Edith Aguilar, Kyle Vincent Marra, Min Qiang, Yang Guang, Richard Lerner, Martin Friedlander; The role of Acid-sensing ion channel 1a in a mouse model of ischemic retinopathy.. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5739. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Acid-sensing ion channel 1a (ASIC1a) has a critical role in neuronal cell death under acidic conditions such as ischemia or metabolic stress. This study examined the role of ASIC1a in a mouse model of ischemic retinopathy and acidosis-induced retinal cell death in vitro.
Oxygen-induced retinopathy (OIR) was induced on C57BL/6J mice via exposure to 75% oxygen from postnatal day 7 (P7) to P12 and subsequent transfer to room air. ASIC1a-blocking combinatorial antibody ASC06-IgG1 developed through the screening of human monoclonal antibody libraries (Qiang M et al. PNAS 2018) was injected intravitreally to OIR eyes. The area of vaso-obliteration (VO), neovascularization (NV) and the number of GFAP positive astrocytes were quantified in ASC06-IgG1 or control antibody treated OIR retina at various time points. We also evaluated retinal astrocytes to determine the mechanism of action of ASC06-IgG1. Primary human retinal astrocytes (HRA) were cultured in pH7.4 or pH5.5 medium with addition of ASC06-IgG1 or an isotype control. Astrocyte viability and apoptosis were measured by CCK-8 assay after 24 hours and flow cytometry for PI and Annexin V staining after 6 hours, respectively.
In OIR, P12 injection of ASIC1a-blocking antibody ASC06-IgG1 significantly decreased the percentage retinal area of VO and NV at P17 by 55% and 41%, respectively, relative contralateral eyes treated with isotype control (p<0.0001). When injected into P7 eyes, ASC06-IgG1 significantly decreased the area of VO in OIR retina by 34% at P10 and 28% at P14. At the same time, the reduction in the number of astrocytes in the VO area was inhibited by ASC06-IgG1 treatment compared to control during hyper- and hypoxic phases (P10; Control: 67% ASC06-IgG1: 5%, P14; Control: 64% ASC06-IgG1: 38% p<0.0001). ASC06-IgG1 treated HRA showed 24% reduction in acidosis-induced apoptosis, and the viability of HRA with ASC06-IgG1 treatment under pH5.5 acidic condition increased by 20% in comparison to isotype control treated HRA (p<0.05, p<0.0001).
Our data suggest that blocking ASIC1a prevents hyperoxia-induced vessel degeneration and hypoxia-derived retinal neovascularization. Blocking ASIC1a may preserve astrocytes during hyper- and hypoxic phases in OIR, thus providing protection from acid-induced astrocyte cell death.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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