bims-mideyd 2023-09-03 papers

bims-mideyd

Biomed News

on Mitochondrial dysfunction in eye diseases

Issue of 2023–09–03
nine papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Prolonged Exposure to High Glucose Induces Premature Senescence Through Oxidative Stress and Autophagy in Retinal Pigment Epithelial Cells.
Astaxanthin ameliorates oxidative stress in lens epithelial cells by regulating GPX4 and ferroptosis.
N-retinylidene-N-retinylethanolamine degradation in human retinal pigment epithelial cells via memantine- and ifenprodil-mediated autophagy.
Hypo-angiogenesis: a possible pathological factor in the development of dry age-related macular degeneration and a novel therapeutic target.
A Method for Real-Time Assessment of Mitochondrial Respiration Using Murine Corneal Biopsy.
Intercellular communication atlas reveals Oprm1 as a neuroprotective factor for retinal ganglion cells.
miR-200a attenuated oxidative stress, inflammation, and apoptosis in dextran sulfate sodium-induced colitis through activation of Nrf2.
Endoplasmic reticulum stress-mediated autophagy alleviates lipopolysaccharide-induced nucleus pulposus cell pyroptosis by inhibiting CHOP signaling in vitro.
Nicotinamide mononucleotide inhibits oxidative stress-induced damage in a SIRT1/NQO-1-dependent manner.

Arch Immunol Ther Exp (Warsz). 2023 Aug 28. 71(1): 21

Prolonged Exposure to High Glucose Induces Premature Senescence Through Oxidative Stress and Autophagy in Retinal Pigment Epithelial Cells.

Chien-Chih Chiu, Kai-Chun Cheng, Yi-Hsiung Lin, Chen-Xi He, Yung-Ding Bow, Chia-Yang Li, Chang-Yi Wu, Hui-Min David Wang, Shwu-Jiuan Sheu.

  Chronic hyperglycemia involves persistent high-glucose exposure and correlates with retinal degeneration. It causes various diseases, including diabetic retinopathy (DR), a major cause of adult vision loss. Most in vitro studies have investigated the damaging short-term effects of high glucose exposure on retinal pigment epithelial (RPE) cells. DR is also a severe complication of diabetes. In this study, we established a model with prolonged high-glucose exposure (15 and 75 mM exogenous glucose for two months) to mimic RPE tissue pathophysiology in patients with hyperglycemia. Prolonged high-glucose exposure attenuated glucose uptake and clonogenicity in ARPE-19 cells. It also significantly increased reactive oxygen species levels and decreased antioxidant protein (superoxide dismutase 2) levels in RPE cells, possibly causing oxidative stress and DNA damage and impairing proliferation. Western blotting showed that autophagic stress, endoplasmic reticulum stress, and genotoxic stress were induced by prolonged high-glucose exposure in RPE cells. Despite a moderate apoptotic cell population detected using the Annexin V-staining assay, the increases in the senescence-associated proteins p53 and p21 and SA-β-gal-positive cells suggest that prolonged high-glucose exposure dominantly sensitized RPE cells to premature senescence. Comprehensive next-generation sequencing suggested that upregulation of oxidative stress and DNA damage-associated pathways contributed to stress-induced premature senescence of ARPE-19 cells. Our findings elucidate the pathophysiology of hyperglycemia-associated retinal diseases and should benefit the future development of preventive drugs. Prolonged high-glucose exposure downregulates glucose uptake and oxidative stress by increasing reactive oxygen species (ROS) production through regulation of superoxide dismutase 2 (SOD2) expression. Autophagic stress, ER stress, and DNA damage stress (genotoxic stress) are also induced by prolonged high-glucose exposure in RPE cells. Consequently, multiple stresses induce the upregulation of the senescence-associated proteins p53 and p21. Although both apoptosis and premature senescence contribute to high glucose exposure-induced anti-proliferation of RPE cells, the present work shows that premature senescence rather than apoptosis is the dominant cause of RPE degeneration, eventually leading to the pathogenesis of DR.

Keywords:  Autophagy; Diabetic retinopathy; Hyperglycemia; Oxidative stress; Premature senescence

DOI:  https://doi.org/10.1007/s00005-023-00686-9
Chem Biol Interact. 2023 Aug 28. pii: S0009-2797(23)00351-4. [Epub ahead of print] 110684

Astaxanthin ameliorates oxidative stress in lens epithelial cells by regulating GPX4 and ferroptosis.

Deqian Kong, Yue Liu, Li Li, Huajun Wang, Ke Li, Guangying Zheng.

  Ferroptosis is a form of regulated cell death closely associated with oxidative stress and mitochondrial dysfunction and is characterised by the accumulation of reactive oxygen species (ROS) and lipid species and iron overload. Damage to human lens epithelial cells (LECs) is associated with age-related cataract progression. Astaxanthin (ATX), a carotenoid with natural antioxidant properties, counteracts ferroptosis in the treatment of various degenerative diseases. However, this mechanism has not been reported with respect to cataract treatment. In this study, the differential expression levels of glutathione peroxidase 4 (GPX4) in the lens of young and aged mice were analysed. Continuous ATX supplementation for 8 months upregulated GPX4 expression in the mouse LECs and delayed the progression of ferroptosis. Upon treatment with erastin, ROS and malondialdehyde accumulated and the mitochondrial membrane potential decreased. At the same time, the expressions of GPX4, SLC7A11, and ferritin were suppressed in human LECs. All of these phenomena were partially reversed by ATX and Fer-1, a ferroptosis inhibitor. This study confirmed that the ATX-mediated targeting of GPX4 might alleviate human LECs damage by inhibiting ferroptosis and ameliorating oxidative stress and that this could represent a promising therapeutic approach for age-related cataract.

Keywords:  Astaxanthin; Ferroptosis; GPX4; Reactive oxygen species

DOI:  https://doi.org/10.1016/j.cbi.2023.110684
Korean J Physiol Pharmacol. 2023 Sep 01. 27(5): 449-456

N-retinylidene-N-retinylethanolamine degradation in human retinal pigment epithelial cells via memantine- and ifenprodil-mediated autophagy.

Jae Rim Lee, Kwang Won Jeong.

  N-methyl-D-aspartate (NMDA) receptors are ionic glutamine receptors involved in brain development and functions such as learning and memory formation. NMDA receptor inhibition is associated with autophagy activation. In this study, we investigated whether the NMDA receptor antagonists, memantine and ifenprodil, induce autophagy in human retinal pigment epithelial cells (ARPE-19) to remove Nretinylidene- N-retinylethanolamine (A2E), an intracellular lipofuscin component. Fluorometric analysis using labeled A2E (A2E-BDP) and confocal microscopic examination revealed that low concentrations of NMDA receptor antagonists, which did not induce cytotoxicity, significantly reduced A2E accumulation in ARPE-19 cells. In addition, memantine and ifenprodil activated autophagy in ARPE-19 cells as measured by microtubule-associated protein 1A/1B-light chain3-II formation and phosphorylated p62 protein levels. Further, to understand the correlation between memantine- and ifenprodil-mediated A2E degradation and autophagy, autophagy-related 5 (ATG5) was depleted using RNA interference. Memantine and ifenprodil failed to degrade A2E in ARPE-19 cells lacking ATG5. Taken together, our study indicates that the NMDA receptor antagonists, memantine and ifenprodil, can remove A2E accumulated in cells via autophagy activation in ARPE-19 cells.

Keywords:  A2E; ARPE-19; Autophagy; Ifenprodil; Memantine

DOI:  https://doi.org/10.4196/kjpp.2023.27.5.449
Med Hypothesis Discov Innov Ophthalmol. 2021 ;10(4): 185-190

Hypo-angiogenesis: a possible pathological factor in the development of dry age-related macular degeneration and a novel therapeutic target.

Pradeep Venkatesh.

   Background: Angiogenesis causes severe vision loss in patients with exudative or wet forms of age-related macular degeneration (AMD). The pathogenesis involves upregulation of several proangiogenic factors, particularly the vascular endothelial growth factor (VEGF). Contrary to the pathogenesis of exudative AMD, molecular events leading to the development of dry AMD remain unclear. Dry AMD is characterized by loss of the retinal pigment epithelium (RPE). The mechanism that triggers RPE cell loss remains unclear. Choriocapillaris development is absent in mice with RPE-specific deletion of VEGF. Moreover, in later life, background VEGF secretion promotes the survival of the RPE and maintains choriocapillaris integrity.
Hypothesis: We hypothesized that reduced synthesis of VEGF (hypo-angiogenesis) or abnormalities in its receptors, VEGF receptor-1 (VEGFR1) and VEGFR2, may be involved in the pathogenesis of non-exudative AMD or dry AMD. If the concept of hypo-angiogenesis as a driver for dry AMD is proven, treatment with VEGF or induction of angiogenesis could be considered. Similar attempts at therapeutic angiogenesis have been actively investigated in cardiac and limb ischemia.
Conclusions: The reasons for a patient developing exudative AMD or dry AMD remain poorly understood. Nevertheless, targeting increased VEGF production in patients with exudative AMD using anti-VEGF drugs is highly efficacious in preserving vision. Similarly, dry AMD may be a manifestation of reduced VEGF synthesis (hypo-angiogenesis) and subsequent decreased RPE cell survival. Experimental studies exploring the possibility of reduced VEGF secretion and/or increased receptor resistance/abnormality could pave the way for clinical trials of angiogenesis to treat dry AMD.

Keywords:  VEGF; aflibercept; age-related macular degeneration; angiogenesis; anti-VEGF; bevacizumab; brolucizumab; dry AMD; exudative AMD; geographic atrophy; hypo-angiogenesis; macular degeneration; ranibizumab; therapeutic angiogenesis; vascular endothelial growth factor; wet macular degeneration

DOI:  https://doi.org/10.51329/mehdiophthal1437
Invest Ophthalmol Vis Sci. 2023 08 01. 64(11): 33

A Method for Real-Time Assessment of Mitochondrial Respiration Using Murine Corneal Biopsy.

Wentao Liang, Li Huang, Tian Yuan, Rui Cheng, Yusuke Takahashi, Gennadiy P Moiseyev, Dimitrios Karamichos, Jian-Xing Ma.

Purpose: To develop and optimize a method to monitor real-time mitochondrial function by measuring the oxygen consumption rate (OCR) in murine corneal biopsy punches with a Seahorse extracellular flux analyzer.
Methods: Murine corneal biopsies were obtained using a biopsy punch immediately after euthanasia. The corneal metabolic profile was assessed using a Seahorse XFe96 pro analyzer, and mitochondrial respiration was analyzed with specific settings.
Results: Real-time adenosine triphosphate rate assay showed that mitochondrial oxidative phosphorylation is a major source of adenosine triphosphate production in ex vivo live murine corneal biopsies. Euthanasia methods (carbon dioxide asphyxiation vs. overdosing on anesthetic drugs) did not affect corneal OCR values. Mouse corneal biopsy punches in 1.5-mm diameter generated higher and more reproducible OCR values than those in 1.0-mm diameter. The biopsy punches from the central and off-central cornea did not show significant differences in OCR values. There was no difference in OCR reading by the tissue orientations (the epithelium side up vs. the endothelium side up). No significant differences were found in corneal OCR levels between sexes, strains (C57BL/6J vs. BALB/cJ), or ages (4, 8, and 32 weeks). Using this method, we showed that the wound healing process in the mouse cornea affected mitochondrial activity.
Conclusions: The present study validated a new strategy to measure real-time mitochondrial function in fresh mouse corneal tissues. This procedure should be helpful for studies of the ex vivo live corneal metabolism in response to genetic manipulations, disease conditions, or pharmacological treatments in mouse models.

DOI: https://doi.org/10.1167/iovs.64.11.33
Res Sq. 2023 Aug 17. pii: rs.3.rs-3193738. [Epub ahead of print]

Intercellular communication atlas reveals Oprm1 as a neuroprotective factor for retinal ganglion cells.

Jiang Qian, Cheng Qian, Ying Xin, Cheng Qi, Hui Wang, Donald Zack, Seth Blackshaw, Samer Hattar, Feng-Quan Zhou.

The progressive death of mature neurons often results in neurodegenerative diseases. While the previous studies have mostly focused on identifying intrinsic mechanisms controlling neuronal survival, the extracellular environment also plays a critical role in regulating cell viability. Here we explore how intercellular communication contributes to the survival of retinal ganglion cells (RGCs) following the optic nerve crush (ONC). Although the direct effect of the ONC is restricted to the RGCs, we observed transcriptomic responses in other retinal cells to the injury based on the single-cell RNA-seq, with astrocytes and Müller glia having the most interactions with RGCs. By comparing the RGC subclasses showing distinct resilience to ONC-induced cell death, we found that the high-survival RGCs tend to have more ligand-receptor interactions with other retinal cells, suggesting that these RGCs are intrinsically programmed to foster more communication with their surroundings. Furthermore, we identified top 47 interactions that are stronger in the high-survival RGCs, likely representing neuroprotective interactions. We performed functional assays on one of the receptors, Mu-opioid receptor (Oprm1), a receptor known to play roles in regulating pain, reward, and addictive behavior. Although Oprm1 is preferentially expressed in intrinsically photosensitive retinal ganglion cells (ipRGCs), its neuroprotective effect could be transferred to multiple RGC subclasses by specific overexpressing Oprm1 in pan-RGCs in ONC, excitotoxicity, and glaucoma models. Lastly, manipulating Oprm1 activity improved visual functions and altered pupillary light response in mice. Our study provides an atlas of cell-cell interactions in both intact and post-ONC retina and an effective strategy to predict molecular mechanisms in neuroprotection, underlying the principal role played by extracellular environment in supporting neuron survival.

DOI: https://doi.org/10.21203/rs.3.rs-3193738/v1
Front Immunol. 2023 ;14 1196065

miR-200a attenuated oxidative stress, inflammation, and apoptosis in dextran sulfate sodium-induced colitis through activation of Nrf2.

Shuai Peng, Lei Shen, Xiaoyun Yu, Jing Wu, Lanlan Zha, Yuan Xia, Hesheng Luo.

   Introduction: Oxidative stress and inflammatory responses are critical factors in ulcerative colitis disease pathogenesis. Nuclear factor erythroid 2-related factor 2 (Nrf2) modulates oxidative stress and suppresses inflammatory responses, and the protective benefits of Nrf2 activation have been associated with the therapy of ulcerative colitis. MicroRNA-200a (miR-200a) could target Kelch-like ECH-associated protein 1 (Keap1) and activate the Nrf2-regulated antioxidant pathway. Nevertheless, whether miR-200a modulates the Keap1/Nrf2 pathway in dextran sulfate sodium (DSS)-induced colonic damage is unknown. Here, our research intends to examine the impact of miR-200a in the model of DSS-induced colitis.
Methods: Prior to DSS intervention, we overexpressed miR-200a in mice for four weeks using an adeno-associated viral (AAV) vector to address this problem. ELISA detected the concentration of inflammation-related cytokines. The genes involved in inflammatory reactions and oxidative stress were identified using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blot, and immunofluorescence. Moreover, we applied siRNAs to weakened Nrf2 expression to confirm the hypothesis that miR-200a provided protection via Nrf2.
Results: The present study discovered miR-200a down-regulation, excessive inflammatory activation, enterocyte apoptosis, colonic dysfunction, and Keap1/Nrf2 antioxidant pathway inactivation in mouse colitis and NCM460 cells under DSS induction. However, our data demonstrated that miR-200a overexpression represses Keap1 and activates the Nrf2 antioxidant pathway, thereby alleviating these adverse alterations in animal and cellular models. Significantly, following Nrf2 deficiency, we failed to observe the protective benefits of miR-200a against colonic damage.
Discussion: Taken together, through activating the Keap1/Nrf2 signaling pathway, miR-200a protected against DSS-induced colonic damage. These studies offer an innovative therapeutic approach for ulcerative colitis.

Keywords:  Nrf2; colitis; inflammation; miR-200a; oxidative stress

DOI:  https://doi.org/10.3389/fimmu.2023.1196065
J Biochem Mol Toxicol. 2023 Aug 31. e23523

Endoplasmic reticulum stress-mediated autophagy alleviates lipopolysaccharide-induced nucleus pulposus cell pyroptosis by inhibiting CHOP signaling in vitro.

Lu Chen, Lei Zhu, Hang Shi, Zhi-Yang Xie, Zan-Li Jiang, Zheng-Yuan Xu, Zi-Jian Zhang, Xiao-Tao Wu.

  Pyroptosis, a newly discovered pro-inflammatory programmed necrosis of cells, serves as an initiating and promoting event that leads to intervertebral disc (IVD) degeneration (IDD). Endoplasmic reticulum stress (ERS) and autophagy are vital regulatory mechanisms of cellular homeostasis, which is also closely related to IDD. However, the role and relationship of ERS and autophagy in the pyroptosis of nucleus pulposus cell (NPC) are not well understood. In this research, we aimed to elucidate the role and mechanism of ERS-C/EBP homologous protein (CHOP) in lipopolysaccharide (LPS)-induced cell pyroptosis and determine its interaction with autophagy. ERS and autophagy inducers or inhibitors were used or not in the preconditioning of rat NPCs. Cell viability, pyroptosis-related protein expression, caspase-1 activity assay, and enzyme-linked immunosorbent assay were performed to observe rat NPC pyroptosis after the treatment of LPS. Activation of the ERS pathway and autophagy were assessed by quantitative real-time PCR, western blot analyses, and immunofluorescence staining assay to classify the molecular mechanisms. Our results showed that LPS stimulation induced NPC pyroptosis with concomitant activation of the ERS-CHOP pathway and initiated autophagy. Activation of the ERS-CHOP pathway exacerbated rat NPC pyroptosis, whereas autophagy inhibited cell pyroptosis. LPS-induced cell pyroptosis and CHOP upregulation were negatively regulated by autophagy. LPS-induced autophagy was depressed by the ERS inhibitor but aggravated by the ERS inducer. Taken together, our findings suggested that LPS induced NPC pyroptosis by activating ERS-CHOP signaling and ERS mediated LPS-induced autophagy, which in turn alleviated NPC pyroptosis by inhibiting CHOP signaling.

Keywords:  autophagy; endoplasmic reticulum stress; intervertebral disc degeneration; nucleus pulposus cell; pyroptosis

DOI:  https://doi.org/10.1002/jbt.23523
Toxicol In Vitro. 2023 Aug 26. pii: S0887-2333(23)00132-7. [Epub ahead of print] 105683

Nicotinamide mononucleotide inhibits oxidative stress-induced damage in a SIRT1/NQO-1-dependent manner.

T Nakajo, N Kitajima, T Katayoshi, K Tsuji-Naito.

  Oxidative stress causes endothelial dysfunction, which is associated with vascular cellular aging and is causally related to cardiovascular disease pathogenesis. Preclinical studies indicate that a nicotinamide adenine dinucleotide (NAD+) precursor, nicotinamide mononucleotide (NMN), alleviates oxidative stress in aged vessels, granting vasoprotective effects. However, the associated cellular mechanism remains largely unclear. In this study, we used human umbilical vein endothelial cells (HUVECs) to demonstrate that NMN inhibits oxidative stress-induced damage by activating the sirtuin 1 (SIRT1)/NAD(P)H: quinone oxidoreductase 1 (NQO-1) axis. We found that NMN inhibited H2O2-induced cytotoxicity and senescence-associated protein expression, such as p16 and p21. Furthermore, NMN prevented H2O2-induced actin cytoskeletal disorganization via inhibiting reactive oxygen species (ROS) production. NMN increased NQO-1 mRNA and protein expression that in turn was abrogated by SIRT1 inhibition, suggesting that NMN-inducible NQO-1 was associated with SIRT1 activity. SIRT1 and NQO-1 inhibition attenuated the inhibitory effect of NMN on H2O2-inducible cytotoxicity, senescence-related protein upregulation, and actin cytoskeletal disorganization. Our findings provide new insights into the mechanism by which NMN exerts protective effects against vascular oxidative stress.

Keywords:  HUVEC; NQO1; Nicotinamide mononucleotide; Oxidative stress; Senescence; Sirtuin

DOI:  https://doi.org/10.1016/j.tiv.2023.105683