bims-mideyd 2023-07-23 papers

bims-mideyd

Biomed News

on Mitochondrial dysfunction in eye diseases

Issue of 2023–07–23
six papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Regulatable Complement Inhibition of the Alternative Pathway Mitigates Wet Age-Related Macular Degeneration Pathology in a Mouse Model.
Mitophagy in the retina: Viewing mitochondrial homeostasis through a new lens.
Downregulation of VEGF in the retinal pigment epithelium followed by choriocapillaris atrophy after NaIO3 treatment in mice.
Slingshot homolog-1-mediated Nrf2 sequestration tips the balance from neuroprotection to neurodegeneration in Alzheimer's disease.
Effects of Brimonidine, Omidenepag Isopropyl, and Ripasudil Ophthalmic Solutions to Protect against H2O2-Induced Oxidative Stress in Human Trabecular Meshwork Cells.
Unravelling the role of NFE2L1 in stress responses and related diseases.

Transl Vis Sci Technol. 2023 Jul 03. 12(7): 17

Regulatable Complement Inhibition of the Alternative Pathway Mitigates Wet Age-Related Macular Degeneration Pathology in a Mouse Model.

Nathaniel B Parsons, Balasubramaniam Annamalai, Bärbel Rohrer.

Purpose: Risk for developing age-related macular degeneration (AMD) is linked to an overactive complement system. In the mouse model of laser-induced choroidal neovascularization (CNV), elevated levels of complement effector molecules, including complement C3, have been identified, and the alternative pathway (AP) is required for pathology. The main soluble AP regular is complement factor H (fH). We have previously shown that AP inhibition via subretinal AAV-mediated delivery of CR2-fH using a constitutive promoter is efficacious in reducing CNV. Here we ask whether the C3 promoter (pC3) effectively drives CR2-fH bioavailability for gene therapy.
Methods: Truncated pC3 was used to generate plasmids pC3-mCherry/CR2-fH followed by production of corresponding AAV5 vectors. pC3 activation was determined in transiently transfected ARPE-19 cells stimulated with H2O2 or normal human serum (+/- antioxidant or humanized CR2-fH, respectively). CNV was analyzed in C57BL/6J mice treated subretinally with AAV5-pC3-mCherry/CR2-fH using imaging (optical coherence tomography [OCT] and fundus imaging), functional (electroretinography [ERG]), and molecular (protein expression) readouts.
Results: Modulation of pC3 in vitro is complement and oxidative stress dependent, as shown by mCherry fluorescence. AAV5-pC3-CR2-fH were identified as safe and effective using OCT and ERG. CR2-fH expression significantly reduced CNV compared to mCherry and was correlated with reduced levels of C3dg/C3d in the retinal pigment epithelium/choroid fraction.
Conclusions: We conclude that complement-dependent regulation of AP inhibition ameliorates AMD pathology as effectively as using a constitutive promoter.
Translational Relevance: The goal of anticomplement therapy is to restore homeostatic levels of complement activation, which might be more easily achievable using a self-regulating system.

DOI: https://doi.org/10.1167/tvst.12.7.17
Prog Retin Eye Res. 2023 Jul 15. pii: S1350-9462(23)00044-7. [Epub ahead of print]96 101205

Mitophagy in the retina: Viewing mitochondrial homeostasis through a new lens.

Juan Ignacio Jiménez-Loygorri, Rocío Benítez-Fernández, Álvaro Viedma-Poyatos, Juan Zapata-Muñoz, Beatriz Villarejo-Zori, Raquel Gómez-Sintes, Patricia Boya.

  Mitochondrial function is key to support metabolism and homeostasis in the retina, an organ that has one of the highest metabolic rates body-wide and is constantly exposed to photooxidative damage and external stressors. Mitophagy is the selective autophagic degradation of mitochondria within lysosomes, and can be triggered by distinct stimuli such as mitochondrial damage or hypoxia. Here, we review the importance of mitophagy in retinal physiology and pathology. In the developing retina, mitophagy is essential for metabolic reprogramming and differentiation of retina ganglion cells (RGCs). In basal conditions, mitophagy acts as a quality control mechanism, maintaining a healthy mitochondrial pool to meet cellular demands. We summarize the different autophagy- and mitophagy-deficient mouse models described in the literature, and discuss the potential role of mitophagy dysregulation in retinal diseases such as glaucoma, diabetic retinopathy, retinitis pigmentosa, and age-related macular degeneration. Finally, we provide an overview of methods used to monitor mitophagy in vitro, ex vivo, and in vivo. This review highlights the important role of mitophagy in sustaining visual function, and its potential as a putative therapeutic target for retinal and other diseases.

Keywords:  Age-related macular degeneration; Autophagy; Diabetic retinopathy; Glaucoma; Metabolism; Mitochondria; Mitophagy; Retinal development; Retinal homeostasis; Retinitis pigmentosa

DOI:  https://doi.org/10.1016/j.preteyeres.2023.101205
Exp Eye Res. 2023 Jul 19. pii: S0014-4835(23)00219-1. [Epub ahead of print] 109598

Downregulation of VEGF in the retinal pigment epithelium followed by choriocapillaris atrophy after NaIO3 treatment in mice.

Toshiro Iwagawa, Kosuke Saita, Hiroshi Sagara, Sumiko Watanabe.

Sodium iodate (NaIO3) induces retinal pigment epithelium (RPE) dysfunction, which leads to photoreceptor degeneration. Previously, we used electron microscopy to show that the administration of NaIO3 resulted in the accumulation of cell debris in the subretinal space, which was thought to be caused by failed phagocytosis in the outer segment of the photoreceptor due to RPE dysfunction. We further analyzed the pathological changes in the retina and choroid of NaIO3-injected mice, and found that the expression of OTX2, an RPE marker, disappeared from central part of the RPE 1 day after NaIO3 administration. Furthermore, fenestrated capillaries (choriocapillaris, CC) adjacent to the RPE could not be identified only 2 days after NaIO3 administration. An examination of the expression of the CC-specific protein plasmalemma vesicle-associated protein (PLVAP), in sections and flat-mount retina/choroid specimens showed destruction of the CC, and complete disappearance of the PLVAP signal 7 days after NaIO3 administration. In contrast, CD31 flat-mount immunohistochemistry of the retina indicated no difference in retinal vessels between NaIO3-treated mice and controls. Electron microscopy showed that the fenestrated capillaries in the kidney and duodenum were morphologically indistinguishable between control and NaIO3-treated mice. We examined cytokine production in the retina and RPE, and found that the Vegfa transcript level in the RPE decreased starting 1 day after NaIO3 administration. Taken together, these observations show that NaIO3 reduces the CC in the early stages of the pathology, which is accompanied by a rapid decrease in Vegfa expression in the RPE.

DOI: https://doi.org/10.1016/j.exer.2023.109598
Proc Natl Acad Sci U S A. 2023 07 25. 120(30): e2217128120

Slingshot homolog-1-mediated Nrf2 sequestration tips the balance from neuroprotection to neurodegeneration in Alzheimer's disease.

Sara Cazzaro, Jung-A A Woo, Xinming Wang, Tian Liu, Shanon Rego, Teresa R Kee, Yeojung Koh, Edwin Vázquez-Rosa, Andrew A Pieper, David E Kang.

  Oxidative damage in the brain is one of the earliest drivers of pathology in Alzheimer's disease (AD) and related dementias, both preceding and exacerbating clinical symptoms. In response to oxidative stress, nuclear factor erythroid 2-related factor 2 (Nrf2) is normally activated to protect the brain from oxidative damage. However, Nrf2-mediated defense against oxidative stress declines in AD, rendering the brain increasingly vulnerable to oxidative damage. Although this phenomenon has long been recognized, its mechanistic basis has been a mystery. Here, we demonstrate through in vitro and in vivo models, as well as human AD brain tissue, that Slingshot homolog-1 (SSH1) drives this effect by acting as a counterweight to neuroprotective Nrf2 in response to oxidative stress and disease. Specifically, oxidative stress-activated SSH1 suppresses nuclear Nrf2 signaling by sequestering Nrf2 complexes on actin filaments and augmenting Kelch-like ECH-associated protein 1 (Keap1)-Nrf2 interaction, independently of SSH1 phosphatase activity. We also show that Ssh1 elimination in AD models increases Nrf2 activation, which mitigates tau and amyloid-β accumulation and protects against oxidative injury, neuroinflammation, and neurodegeneration. Furthermore, loss of Ssh1 preserves normal synaptic function and transcriptomic patterns in tauP301S mice. Importantly, we also show that human AD brains exhibit highly elevated interactions of Nrf2 with both SSH1 and Keap1. Thus, we demonstrate here a unique mode of Nrf2 blockade that occurs through SSH1, which drives oxidative damage and ensuing pathogenesis in AD. Strategies to inhibit SSH1-mediated Nrf2 suppression while preserving normal SSH1 catalytic function may provide new neuroprotective therapies for AD and related dementias.

Keywords:  Nrf2; alzheimer; oxidative stress; slingshot; tauopathy

DOI:  https://doi.org/10.1073/pnas.2217128120
Curr Eye Res. 2023 Jul 19. 1-12

Effects of Brimonidine, Omidenepag Isopropyl, and Ripasudil Ophthalmic Solutions to Protect against H2O2-Induced Oxidative Stress in Human Trabecular Meshwork Cells.

Mengxuan Liu, Megumi Honjo, Reiko Yamagishi, Makoto Aihara.

   PURPOSE: We investigated whether hydrogen peroxide (H2O2)-induced oxidative stress causes human trabecular meshwork (HTM) cell dysfunction observed in open angle glaucoma (OAG) in vitro, and the effects of topical glaucoma medications on oxidative stress in HTM cells.
METHODS: We used commercially available ophthalmic solutions of brimonidine, omidenepag isopropyl, and ripasudil in the study. HTM cells were exposed to H2O2 for 1 h, with or without glaucoma medications. We assessed cell viability and senescence via WST-1 and senescence-associated-β-galactosidase (SA-β-Gal) activity assays. After exposure to H2O2 and glaucoma medications, we evaluated changes in markers of fibrosis and stress by using real-time quantitative polymerase chain reaction (qPCR) to measure the mRNA levels of collagen type I alpha 1 chain (COL1A1), fibronectin, alpha-smooth muscle actin (α-SMA), matrix metalloproteinase-2 (MMP-2), endoplasmic reticulum stress markers of C/EBP homologous protein (CHOP), 78-kDa glucose-regulated protein (GRP78), and splicing X-box binding protein-1 (sXBP-1).
RESULTS: HTM cell viability decreased and SA-β-Gal activity increased significantly after exposure to H2O2. Treatment with three ophthalmic solutions attenuated these changes. Real-time qPCR revealed that H2O2 upregulated the mRNA levels of COL1A1, fibronectin, α-SMA, CHOP, GRP78, and sXBP-1, whereas it downregulated MMP-2 mRNA expression significantly. Brimonidine suppressed the upregulation of stress markers CHOP and GRP78. Additionally, omidenepag isopropyl and ripasudil decreased the upregulation of COL1A1 and sXBP-1. Furthermore, ripasudil significantly suppressed fibrotic markers fibronectin and α-SMA, compared with the other two medications.
CONCLUSION: In vitro, H2O2 treatment of HTM cells induced characteristic changes of OAG, such as fibrosis changes and the upregulation of stress markers. These glaucomatous changes were attenuated by additional treatments with brimonidine, omidenepag isopropyl, and ripasudil ophthalmic solutions.

Keywords:  Human trabecular meshwork cells; endoplasmic reticulum stress; hydrogen peroxide; ophthalmic solutions; oxidative stress

DOI:  https://doi.org/10.1080/02713683.2023.2235892
Redox Biol. 2023 Jul 14. pii: S2213-2317(23)00220-3. [Epub ahead of print]65 102819

Unravelling the role of NFE2L1 in stress responses and related diseases.

Xingzhu Liu, Chang Xu, Wanglong Xiao, Nianlong Yan.

  The nuclear factor erythroid 2 (NF-E2)-related factor 1 (NFE2L1, also known as Nrf1) is a highly conserved transcription factor that belongs to the CNC-bZIP subfamily. Its significance lies in its control over redox balance, proteasome activity, and organ integrity. Stress responses encompass a series of compensatory adaptations utilized by cells and organisms to cope with extracellular or intracellular stress initiated by stressful stimuli. Recently, extensive evidence has demonstrated that NFE2L1 plays a crucial role in cellular stress adaptation by 1) responding to oxidative stress through the induction of antioxidative responses, and 2) addressing proteotoxic stress or endoplasmic reticulum (ER) stress by regulating the ubiquitin-proteasome system (UPS), unfolded protein response (UPR), and ER-associated degradation (ERAD). It is worth noting that NFE2L1 serves as a core factor in proteotoxic stress adaptation, which has been extensively studied in cancer and neurodegeneration associated with enhanced proteasomal stress. In these contexts, utilization of NFE2L1 inhibitors to attenuate proteasome "bounce-back" response holds tremendous potential for enhancing the efficacy of proteasome inhibitors. Additionally, abnormal stress adaptations of NFE2L1 and disturbances in redox and protein homeostasis contribute to the pathophysiological complications of cardiovascular diseases, inflammatory diseases, and autoimmune diseases. Therefore, a comprehensive exploration of the molecular basis of NFE2L1 and NFE2L1-mediated diseases related to stress responses would not only facilitate the identification of novel diagnostic and prognostic indicators but also enable the identification of specific therapeutic targets for NFE2L1-related diseases.

Keywords:  Adaptive responses; Cancer; NFE2L1; Neurodegeneration; Oxidative stress; Proteasome

DOI:  https://doi.org/10.1016/j.redox.2023.102819