Abstract: Clinically, a large proportion of glaucoma patients undergo repeated intraocular pressure (IOP) spike (Spike IOP) attacks during their sleep, which may facilitate retinopathy. In this study, we established a mouse model of repeated transient Spike IOP to investigate the direct damage to the retina following Spike IOP attacks, and elucidated the underlying molecular mechanism. We analyzed the changes in the number of retinal ganglion cells (RGCs) via immunofluorescence. Thereafter, we detected retinal cell apoptosis via terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL) staining, and performed RNA sequencing (RNA-seq) to reveal the underlying molecular mechanism. Finally, we validated the expression of key molecules in the endoplasmic reticulum (ER) stress pathway using quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis. Results revealed a time-dependent RGC loss in Spike IOP, evidenced by a reduction in the number of Brn3a-positive RGCs in experimental eyes following a 7-d continuous treatment with Spike IOP. In addition, TUNEL staining indicated that apoptosis of retinal cells started in the outer nuclear layer (ONL), and then spread to the ganglion cell layer (GCL) with time. RNA-seq analysis revealed that ER stress might be involved in Spike IOP-induced retinal injury. This result was corroborated by western blot, which revealed upregulation of ER stress-related proteins including binding immunoglobulin protein/glucose-regulated protein 78 (BiP/GRP78), phosphorylated inositol-requiring enzyme 1 (p-IRE1), unspliced X-box-binding protein 1 (XBP1-u), spliced X-box-binding protein 1 (XBP1-s), phosphorylated c-Jun N-terminal kinase (p-JNK), C/EBP-homologous protein (CHOP), and B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax). These findings indicate that repeated IOP transients are detrimental to the retina, while ER stress plays an important role in retinal cell apoptosis in this situation. Notably, repeated Spike IOP among glaucoma patients is a crucial factor for progressive retinopathy.

内质网应激参与反复瞬时高眼压诱导的视网膜损伤

[1]AsraniS, ZeimerR, WilenskyJ, et al., 2000. Large diurnal fluctuations in intraocular pressure are an independent risk factor in patients with glaucoma. J Glaucoma, 9(2):134-142.

[2]BarkanaY, AnisS, LiebmannJ, et al., 2006. Clinical utility of intraocular pressure monitoring outside of normal office hours in patients with glaucoma. Arch Ophthalmol, 124(6):793-797.

[3]ChoiSS, ZawadzkiRJ, LimMC, et al., 2011. Evidence of outer retinal changes in glaucoma patients as revealed by ultrahigh-resolution in vivo retinal imaging. Br J Ophthalmol, 95(1):131-141.

[4]di PierdomenicoJ, García-AyusoD, PinillaI, et al., 2017. Early events in retinal degeneration caused by rhodopsin mutation or pigment epithelium malfunction: differences and similarities. Front Neuroanat, 11:14.

[5]di PierdomenicoJ, García-AyusoD, Agudo-BarriusoM, et al., 2019. Role of microglial cells in photoreceptor degeneration. Neural Regen Res, 14(7):1186-1190.

[6]García-AyusoD, Ortín-MartínezA, Jiménez-LópezM, et al., 2013. Changes in the photoreceptor mosaic of P23H-1 rats during retinal degeneration: implications for rod-cone dependent survival. Invest Ophthalmol Vis Sci, 54(8):5888-5900.

[7]García-AyusoD, di PierdomenicoJ, Agudo-BarriusoM, et al., 2018. Retinal remodeling following photoreceptor degeneration causes retinal ganglion cell death. Neural Regen Res, 13(11):1885-1886.

[8]HetzC, SaxenaS, 2017. ER stress and the unfolded protein response in neurodegeneration. Nat Rev Neurol, 13(8):477-491.

[9]HetzC, ThielenP, MatusS, et al., 2009. XBP-1 deficiency in the nervous system protects against amyotrophic lateral sclerosis by increasing autophagy. Genes Dev, 23(19):2294-2306.

[10]HouRW, ZhangZ, YangDY, et al., 2016. Pressure balance and imbalance in the optic nerve chamber: The Beijing Intracranial and Intraocular Pressure (iCOP) study. Sci China Life Sci, 59(5):495-503.

[11]HuY, ParkKK, YangL, et al., 2012. Differential effects of unfolded protein response pathways on axon injury-induced death of retinal ganglion cells. Neuron, 73(3):445-452.

[12]KimI, XuWJ, ReedJC, 2008. Cell death and endoplasmic reticulum stress: disease relevance and therapeutic opportunities. Nat Rev Drug Discov, 7(12):1013-1030.

[13]KonstasAGP, QuarantaL, MikropoulosDG, et al., 2012. Peak intraocular pressure and glaucomatous progression in primary open-angle glaucoma. J Ocul Pharmacol Ther, 28(1):26-32.

[14]KroegerH, MessahC, AhernK, et al., 2012. Induction of endoplasmic reticulum stress genes, BiP and Chop, in genetic and environmental models of retinal degeneration. Invest Ophthalmol Vis Sci, 53(12):7590-7599.

[15]KumarV, Mesentier-LouroLA, OhAJ, et al., 2019. Increased ER stress after experimental ischemic optic neuropathy and improved RGC and oligodendrocyte survival after treatment with chemical chaperon. Invest Ophthalmol Vis Sci, 60(6):1953-1966.

[16]LiJ, YangDY, KwongJMK, et al., 2020. Long-term follow-up of optic neuropathy in chronic low cerebrospinal fluid pressure monkeys: The Beijing Intracranial and Intraocular Pressure (iCOP) study. Sci China Life Sci, 63(11):1762-1765.

[17]LinT, LeeJE, KangJW, et al., 2019. Endoplasmic reticulum (ER) stress and unfolded protein response (UPR) in mammalian oocyte maturation and preimplantation embryo development. Int J Mol Sci, 20(2):409.

[18]LiuJHK, ZhangXY, KripkeDF, et al., 2003. Twenty-four-hour intraocular pressure pattern associated with early glaucomatous changes. Invest Ophthalmol Vis Sci, 44(4):1586-1590.

[19]LiuJHK, MedeirosFA, SlightJR, et al., 2010. Diurnal and nocturnal effects of brimonidine monotherapy on intraocular pressure. Ophthalmology, 117(11):2075-2079.

[20]MayCA, MittagT, 2006. Optic nerve degeneration in the DBA/2NNia mouse: is the lamina cribrosa important in the development of glaucomatous optic neuropathy? Acta Neuropathol, 111(2):158-167.

[21]NorkTM, ver HoeveJN, PoulsenGL, et al., 2000. Swelling and loss of photoreceptors in chronic human and experimental glaucomas. Arch Ophthalmol, 118(2):235-245.

[22]Nouri-MahdaviK, HoffmanD, ColemanAL, et al., 2004. Predictive factors for glaucomatous visual field progression in the advanced glaucoma intervention study. Ophthalmology, 111(9):1627-1635.

[23]Ortín-MartínezA, Salinas-NavarroM, Nadal-NicolásFM, et al., 2015. Laser-induced ocular hypertension in adult rats does not affect non-RGC neurons in the ganglion cell layer but results in protracted severe loss of cone-photoreceptors. Exp Eye Res, 132:17-33.

[24]PandaS, JonasJB, 1992. Decreased photoreceptor count in human eyes with secondary angle-closure glaucoma. Invest Ophthalmol Vis Sci, 33(8):2532-2536.

[25]SalminenA, KauppinenA, HyttinenJMT, et al., 2010. Endoplasmic reticulum stress in age-related macular degeneration: trigger for neovascularization. Mol Med, 16(11-12):535-542.

[26]SimD, FruttigerM, 2013. Keeping blood vessels out of sight. eLife, 2:e00948.

[27]SunH, WangY, PangIH, et al., 2011. Protective effect of a JNK inhibitor against retinal ganglion cell loss induced by acute moderate ocular hypertension. Mol Vis, 17:864-875.

[28]ThamYC, LiX, WongTY, et al., 2014. Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis. Ophthalmology, 121(11):2081-2090.

[29]WangJW, Valiente-SorianoFJ, Nadal-NicolásFM, et al., 2017. MicroRNA regulation in an animal model of acute ocular hypertension. Acta Ophthalmol, 95(1):e10-e21.

[30]WeinrebRN, AungT, MedeirosFA, 2014. The pathophysiology and treatment of glaucoma: a review. JAMA, 311(18):1901-1911.

[31]XuSC, GauthierAC, LiuJ, 2016. The application of a contact lens sensor in detecting 24-hour intraocular pressure-related patterns. J Ophthalmol, 2016:4727423.

[32]XuLJ, LiSL, ZemonV, et al., 2020. Central visual function and inner retinal structure in primary open-angle glaucoma. J Zhejiang Univ-Sci B (Biomed & Biotechnol), 21(4):305-314.

[33]YangL, LiSH, MiaoLQ, et al., 2016. Rescue of glaucomatous neurodegeneration by differentially modulating neuronal endoplasmic reticulum stress molecules. J Neurosci, 36(21):5891-5903.

[34]YangLP, WuLM, GuoXJ, et al., 2007. Activation of endoplasmic reticulum stress in degenerating photoreceptors of the rd1 mouse. Invest Ophthalmol Vis Sci, 48(11):5191-5198.

[35]ZeimerRC, WilenskyJT, GieserDK, et al., 1991. Association between intraocular pressure peaks and progression of visual field loss. Ophthalmology, 98(1):64-69.

[36]ZhaoZN, YuXW, YangX, et al., 2020. Elevated intraocular pressure causes cellular and molecular retinal injuries, advocating a more moderate intraocular pressure setting during phacoemulsification surgery. Int Ophthalmol, 40(12):3323-3336.

[37]ZhouL, ChenW, LinDY, et al., 2019. Neuronal apoptosis, axon damage and synapse loss occur synchronously in acute ocular hypertension. Exp Eye Res, 180:77-85.