bims-mideyd 2023-07-30 papers

bims-mideyd

Biomed News

on Mitochondrial dysfunction in eye diseases

Issue of 2023–07–30
eight papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Oxidative Stress and Antioxidants in Age-Related Macular Degeneration.
Antioxidative Role of Heterophagy, Autophagy, and Mitophagy in the Retina and Their Association with the Age-Related Macular Degeneration (AMD) Etiopathogenesis.
β-Asarone Alleviates High-Glucose-Induced Oxidative Damage via Inhibition of ROS Generation and Inactivation of the NF-κB/NLRP3 Inflammasome Pathway in Human Retinal Pigment Epithelial Cells.
DNMT1 regulates miR-20a/TXNIP-mediated pyroptosis of retinal pigment epithelial cells through DNA methylation.
Microglia at Sites of Atrophy Restrict the Progression of Retinal Degeneration via Galectin-3 and Trem2 Interactions.
Oxidative Stress: A Suitable Therapeutic Target for Optic Nerve Diseases?
Potential Therapeutic Functions of PU-91 and Quercetin in Personalized Cybrids Derived from Patients with Age-Related Macular Degeneration, Keratoconus, and Glaucoma.
The role of mitochondrial genes on nuclear gene expression in neovascular age related macular degeneration: analysis of nuclear VEGF gene expression after ranibizumab treatment in cytoplasmic hybrid retinal pigment epithelial cell lines correlated with clinical evolution.

Antioxidants (Basel). 2023 Jul 03. pii: 1379. [Epub ahead of print]12(7):

Oxidative Stress and Antioxidants in Age-Related Macular Degeneration.

Neetu Kushwah, Kiran Bora, Meenakshi Maurya, Madeline C Pavlovich, Jing Chen.

  Oxidative stress plays a crucial role in aging-related eye diseases, including age-related macular degeneration (AMD), cataracts, and glaucoma. With age, antioxidant reparative capacity decreases, and excess levels of reactive oxygen species produce oxidative damage in many ocular cell types underling age-related pathologies. In AMD, loss of central vision in the elderly is caused primarily by retinal pigment epithelium (RPE) dysfunction and degeneration and/or choroidal neovascularization that trigger malfunction and loss of photo-sensing photoreceptor cells. Along with various genetic and environmental factors that contribute to AMD, aging and age-related oxidative damage have critical involvement in AMD pathogenesis. To this end, dietary intake of antioxidants is a proven way to scavenge free radicals and to prevent or slow AMD progression. This review focuses on AMD and highlights the pathogenic role of oxidative stress in AMD from both clinical and experimental studies. The beneficial roles of antioxidants and dietary micronutrients in AMD are also summarized.

Keywords:  age-related macular degeneration; antioxidant; choroidal neovascularization; oxidative stress; reactive oxygen species; retinal pigment epithelium

DOI:  https://doi.org/10.3390/antiox12071379
Antioxidants (Basel). 2023 Jun 29. pii: 1368. [Epub ahead of print]12(7):

Antioxidative Role of Heterophagy, Autophagy, and Mitophagy in the Retina and Their Association with the Age-Related Macular Degeneration (AMD) Etiopathogenesis.

Małgorzata Nita, Andrzej Grzybowski.

  Age-related macular degeneration (AMD), an oxidative stress-linked neurodegenerative disease, leads to irreversible damage of the central retina and severe visual impairment. Advanced age and the long-standing influence of oxidative stress and oxidative cellular damage play crucial roles in AMD etiopathogenesis. Many authors emphasize the role of heterophagy, autophagy, and mitophagy in maintaining homeostasis in the retina. Relevantly modifying the activity of both macroautophagy and mitophagy pathways represents one of the new therapeutic strategies in AMD. Our review provides an overview of the antioxidative roles of heterophagy, autophagy, and mitophagy and presents associations between dysregulations of these molecular mechanisms and AMD etiopathogenesis. The authors performed an extensive analysis of the literature, employing PubMed and Google Scholar, complying with the 2013-2023 period, and using the following keywords: age-related macular degeneration, RPE cells, reactive oxygen species, oxidative stress, heterophagy, autophagy, and mitophagy. Heterophagy, autophagy, and mitophagy play antioxidative roles in the retina; however, they become sluggish and dysregulated with age and contribute to AMD development and progression. In the retina, antioxidative roles also play in RPE cells, NFE2L2 and PGC-1α proteins, NFE2L2/PGC-1α/ARE signaling cascade, Nrf2 factor, p62/SQSTM1/Keap1-Nrf2/ARE pathway, circulating miRNAs, and Yttrium oxide nanoparticles performed experimentally in animal studies.

Keywords:  RPE cells; age-related macular degeneration; autophagy; heterophagy; mitophagy; oxidative stress; reactive oxygen species

DOI:  https://doi.org/10.3390/antiox12071368
Antioxidants (Basel). 2023 Jul 11. pii: 1410. [Epub ahead of print]12(7):

β-Asarone Alleviates High-Glucose-Induced Oxidative Damage via Inhibition of ROS Generation and Inactivation of the NF-κB/NLRP3 Inflammasome Pathway in Human Retinal Pigment Epithelial Cells.

Cheol Park, Hee-Jae Cha, Hyun Hwangbo, EunJin Bang, Su Hyun Hong, Kyoung Seob Song, Jeong Sook Noh, Do-Hyung Kim, Gi-Young Kim, Yung Hyun Choi.

  Diabetic retinopathy (DR) is the leading cause of vision loss and a major complication of diabetes. Hyperglycemia-induced accumulation of reactive oxygen species (ROS) is an important risk factor for DR. β-asarone, a major component of volatile oil extracted from Acori graminei Rhizoma, exerts antioxidant effects; however, its efficacy in DR remains unknown. In this study, we investigated whether β-asarone inhibits high-glucose (HG)-induced oxidative damage in human retinal pigment epithelial (RPE) ARPE-19 cells. We found that β-asarone significantly alleviated cytotoxicity, apoptosis, and DNA damage in HG-treated ARPE-19 cells via scavenging of ROS generation. β-Asarone also significantly attenuated the excessive accumulation of lactate dehydrogenase and mitochondrial ROS by increasing the manganese superoxide dismutase and glutathione activities. HG conditions markedly increased the release of interleukin (IL)-1β and IL-18 and upregulated their protein expression and activation of the nuclear factor-kappa B (NF-κB) signaling pathway, whereas β-asarone reversed these effects. Moreover, expression levels of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome multiprotein complex molecules, including thioredoxin-interacting protein, NLRP3, apoptosis-associated speck-like protein containing a caspase-recruitment domain, and cysteinyl aspartate-specific proteinase-1, were increased in ARPE-19 cells under HG conditions. However, their expression levels remained similar to those in the control group in the presence of β-asarone. Therefore, β-asarone protects RPE cells from HG-induced injury by blocking ROS generation and NF-κB/NLRP3 inflammasome activation, indicating its potential as a therapeutic agent for DR treatment.

Keywords:  NF-κB; NLRP3 inflammasome; ROS; high glucose; β-asarone

DOI:  https://doi.org/10.3390/antiox12071410
Mol Cell Endocrinol. 2023 Jul 26. pii: S0303-7207(23)00163-6. [Epub ahead of print] 112012

DNMT1 regulates miR-20a/TXNIP-mediated pyroptosis of retinal pigment epithelial cells through DNA methylation.

Xiaoting Xi, Min Wang, Qianbo Chen, Jia Ma, Junyan Zhang, Yan Li.

   BACKGROUND: Pyroptosis of retinal pigment epithelium (RPE) cells is associated with the etiology of diabetic retinopathy (DR). In this study, we investigated the effect of DNMT1 on RPE cell pyroptosis by regulating miR-20a/TXNIP expression through DNA methylation.
METHODS: High glucose (HG)-induced ARPE-19 RPE cells and mice were injected with streptozotocin (STZ) to generate DR cells and animal models. RT‒qPCR was used to detect the expression of miR-20a, and methylation-specific PCR (MS-PCR) was used to determine the occurrence of methylation of miR-20a. The expression of pyroptosis-related proteins (caspase-1 and NLRP3) and DNA methyltransferase (DNMT1) was detected by western blotting, and the expression of inflammatory factors (IL-1β and IL-18) was detected by ELISA. Apoptosis was detected by flow cytometry and TUNEL. HE staining was used to observe the pathological changes in retinal tissue in mice.
RESULTS: In HG-induced DR cell models, the expression of miR-20a was significantly downregulated, while the expression of inflammatory factors (IL-1β, IL-18) and pyroptosis-associated proteins (caspase-1, NLRP3) was significantly upregulated. Transfection of miR-20a mimic can effectively reverse HG-induced pyroptosis and release of inflammatory factors. DNMT1 promotes miR-20a methylation and inhibits the expression of miR-20a. DNMT1-mediated methylation is involved in the pyroptosis process of high glucose-induced RPE cells, and silencing DNMT1 can promote the expression of miR-20a, thereby inhibiting the release of IL-1β and IL-18 and reducing the occurrence of cell pyrozoosis. miR-20a targets negative regulation of TXNIP expression, and overexpression of TXNIP can effectively reverse the inhibitory effect of miR-20a on pyroptosis. The methylation inhibitor 5-AZ can inhibit the occurrence of pyroptosis and DR processes, while treatment with a miR-20a inhibitor or OE-TXNIP can reverse the effect of 5-AZ.
CONCLUSION: DNMT1 promotes DNA methylation, decreases the expression of miR-20a and increases the expression of TXNIP, which ultimately leads to the occurrence of pyroptosis in RPE cells.

Keywords:  DNMT1; Diabetic retinopathy; Pyroptosis; Retinal pigment epithelium cells; miR-20a/TXNIP

DOI:  https://doi.org/10.1016/j.mce.2023.112012
bioRxiv. 2023 Jul 19. pii: 2023.07.19.549403. [Epub ahead of print]

Microglia at Sites of Atrophy Restrict the Progression of Retinal Degeneration via Galectin-3 and Trem2 Interactions.

Chen Yu, Eleonora M Lad, Rose Mathew, Sejiro Littleton, Yun Chen, Kai Schlepckow, Simone Degan, Lindsey Chew, Joshua Amason, Joan Kalnitsky, Catherine Bowes Rickman, Alan D Proia, Marco Colonna, Christian Haass, Daniel R Saban.

Degenerative diseases of the outer retina, including age-related macular degeneration (AMD), are characterized by atrophy of photoreceptors and retinal pigment epithelium (RPE). In these blinding diseases, macrophages are known to accumulate ectopically at sites of atrophy, but their ontogeny and functional specialization within this atrophic niche remain poorly understood, especially in the human context. Here, we uncovered a transcriptionally unique profile of microglia, marked by galectin-3 upregulation, at atrophic sites in mouse models of retinal degeneration and in human AMD. Using disease models, we found that conditional deletion of galectin-3 in microglia led to defects in phagocytosis and consequent augmented photoreceptor death, RPE damage and vision loss, suggestive of a protective role. Mechanistically, Trem2 signaling orchestrated the migration of microglial cells to sites of atrophy, and there, induced galectin-3 expression. Moreover, pharmacologic Trem2 agonization led to heightened protection, but only in a galectin-3-dependent manner, further signifying the functional interdependence of these two molecules. Likewise in elderly human subjects, we identified a highly conserved population of microglia at the transcriptomic, protein and spatial levels, and this population was enriched in the macular region of postmortem AMD subjects. Collectively, our findings reveal an atrophy-associated specialization of microglia that restricts the progression of retinal degeneration in mice and further suggest that these protective microglia are conserved in AMD.
One Sentence Summary: A common neuroprotective response of microglia at the site of retinal atrophy is identified in mice and humans.

DOI: https://doi.org/10.1101/2023.07.19.549403
Antioxidants (Basel). 2023 Jul 20. pii: 1465. [Epub ahead of print]12(7):

Oxidative Stress: A Suitable Therapeutic Target for Optic Nerve Diseases?

Francesco Buonfiglio, Elsa Wilma Böhm, Norbert Pfeiffer, Adrian Gericke.

  Optic nerve disorders encompass a wide spectrum of conditions characterized by the loss of retinal ganglion cells (RGCs) and subsequent degeneration of the optic nerve. The etiology of these disorders can vary significantly, but emerging research highlights the crucial role of oxidative stress, an imbalance in the redox status characterized by an excess of reactive oxygen species (ROS), in driving cell death through apoptosis, autophagy, and inflammation. This review provides an overview of ROS-related processes underlying four extensively studied optic nerve diseases: glaucoma, Leber's hereditary optic neuropathy (LHON), anterior ischemic optic neuropathy (AION), and optic neuritis (ON). Furthermore, we present preclinical findings on antioxidants, with the objective of evaluating the potential therapeutic benefits of targeting oxidative stress in the treatment of optic neuropathies.

Keywords:  Leber’s hereditary optic neuropathy; glaucoma; ischemic optic neuropathy; optic nerve; optic neuritis; oxidative stress; retinal ganglion cell

DOI:  https://doi.org/10.3390/antiox12071465
Antioxidants (Basel). 2023 Jun 22. pii: 1326. [Epub ahead of print]12(7):

Potential Therapeutic Functions of PU-91 and Quercetin in Personalized Cybrids Derived from Patients with Age-Related Macular Degeneration, Keratoconus, and Glaucoma.

Nasim Salimiaghdam, Lata Singh, Mithalesh Kumar Singh, Marilyn Chwa, Shari Atilano, Zahra Mohtashami, Anthony Nesburn, Baruch D Kuppermann, M Cristina Kenney.

  The aim of this study is to investigate the therapeutic potential of higher doses of PU-91, quercetin, or in combination on transmitochondrial cybrid cell lines with various mtDNA haplogroups derived from patients with age-related macular degeneration (AMD), glaucoma (Glc), keratoconus (KC), and normal (NL) individuals. Cybrids were treated with PU-91 (P) (200 µM) alone, quercetin (Q) (20 µM) alone, or a combination of PU-91 and quercetin (P+Q) for 48 h. Cellular metabolism and the intracellular levels of reactive oxygen species (ROS) were measured by MTT and H2DCFDA assays, respectively. Quantitative real-time PCR was performed to measure the expression levels of genes associated with mitochondrial biogenesis, antioxidant enzymes, inflammation, apoptosis, and senescence pathways. PU-91(P) (i) improves cellular metabolism in AMD cybrids, (ii) decreases ROS production in AMD cybrids, and (iii) downregulates the expression of LMNB1 in AMD cybrids. Combination treatment of PU-91 plus quercetin (P+Q) (i) improves cellular metabolism in AMD, (ii) induces higher expression levels of TFAM, SOD2, IL6, and BAX in AMD cybrids, and (iii) upregulates CDKN1A genes expression in all disease cybrids. Our study demonstrated that the P+Q combination improves cellular metabolism and mitochondrial biogenesis in AMD cybrids, but senescence is greatly exacerbated in all cybrids regardless of disease type by the P+Q combined treatment.

Keywords:  AMD cybrids; Glc cybrids; KC cybrids; PU-91; combined PU-91 and quercetin; quercetin

DOI:  https://doi.org/10.3390/antiox12071326
Int J Retina Vitreous. 2023 Jul 25. 9(1): 44

The role of mitochondrial genes on nuclear gene expression in neovascular age related macular degeneration: analysis of nuclear VEGF gene expression after ranibizumab treatment in cytoplasmic hybrid retinal pigment epithelial cell lines correlated with clinical evolution.

Rodrigo Donato Costa, Farid José Thomaz Neto, M Tarek Moustafa, Shari R Atilano, Marilyn Chwa, Javier Cáceres-Del-Carpi, Mohamed Hamid Mohamed, M Cristina Kenney, Baruch D Kuppermann.

PURPOSE: The present study tests the hypothesis that mitochondrial genes have retrograde signaling capacity that influences the expression of nuclear genes related to angiogenesis pathways. Cytoplasmic hybrid (cybrid) in vitro cell lines with patient specific mitochondria inserted into an immortalized retinal pigment epithelial cell line (ARPE-19) were used to test this hypothesis. This type of analysis can provide important information to identify the optimal regimen of anti-VEGF treatment, personalizing age-related macular degeneration (AMD) therapies.
METHODS: Mitochondria deficient ARPE-19 cells (Rho0) were fused with AMD donor's platelets to create individual cybrid cell lines containing mitochondria from patients with phenotypic AMD disease and nuclear DNA from the immortalized RPE cell line. The cybrids were treated with Ranibizumab (Lucentis, Genentech, San Francisco, CA), at 4 different concentrations for 24 h, and subsequently the levels of reactive oxygen species (ROS), gene expression for VEGF-A, hypoxia-inducible factor 1-alpha (HIF1-a) and manganese superoxide dismutase (SOD2) were measured. The clinical evolution of the two AMD-donors were correlated with the molecular findings found in their 'personalized' cybrids.
RESULTS: Cybrids from Patient-01 showed down-regulation of gene expression of VEGF-A and HIF-1a at both 1X and 4X Ranibizumab concentrations. Patient-01 AMD cybrid cultures had an increase in the ROS levels at 1X (P = 0.0317), no changes at 2X (P = 0.8350) and a decrease at 4X (P = 0.0015) and 10X (P = 0.0011) of Ranibizumab. Clinically, Patient-01 responded to anti-VEGF therapy but eventually developed geographic atrophy. Patient-02 cybrids demonstrated up-regulation of gene expression of VEGF-A and HIF-1a at Ranibizumab 1X and 4X concentrations. There was decreased ROS levels with Ranibizumab 1X (P = 0.1606), 2X (P = 0.0388), 4X (P = 0.0010) and 10X (P = < 0.0001). Clinically, Patient-02 presented with a neovascular lesion associated with a prominent production of intraretinal fluid in clinical follow-up requiring regular and repeated intravitreal injections of Ranibizumab with recurrent subretinal fluid.
CONCLUSIONS: Our cybrid model has the potential to help personalize the treatment regimen with anti-VEGF drugs in patients with neovascular AMD. Further investigation is needed to better understand the role that the mitochondria play in the cellular response to anti-VEGF drugs. Future studies that focus on this model have the potential to help personalize anti-VEGF treatment.

DOI: https://doi.org/10.1186/s40942-023-00476-7