bims-mideyd 2022-11-27 papers

bims-mideyd

Biomed News

on Mitochondrial dysfunction in eye diseases

Issue of 2022‒11‒27
seven papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Protrusion of KCNJ13 Gene Knockout Retinal Pigment Epithelium Due to Oxidative Stress-Induced Cell Death.
RIP140-Mediated NF-κB Inflammatory Pathway Promotes Metabolic Dysregulation in Retinal Pigment Epithelium Cells.
Intercellular communication analysis of the human retinal pigment epithelial and choroidal cells predicts pathways associated with aging, cellular senescence and age-related macular degeneration.
Microglia-Neutrophil Interactions Drive Dry AMD-like Pathology in a Mouse Model.
cGMP Signaling in the Neurovascular Unit-Implications for Retinal Ganglion Cell Survival in Glaucoma.
Changes in Mitochondrial Size and Morphology in the RPE and Photoreceptors of the Developing and Ageing Zebrafish.
Inhibition of ferroptosis promotes retina ganglion cell survival in experimental optic neuropathies.

Invest Ophthalmol Vis Sci. 2022 11 01. 63(12): 29

Protrusion of KCNJ13 Gene Knockout Retinal Pigment Epithelium Due to Oxidative Stress-Induced Cell Death.

Yuki Kanzaki, Hirofumi Fujita, Keita Sato, Mio Hosokawa, Hiroshi Matsumae, Yuki Morizane, Hideyo Ohuchi.

Purpose: This study was performed to elucidate the mechanisms of morphological abnormalities in a Leber congenital amaurosis 16 (LCA16) cell model using KCNJ13 knockout (KO) retinal pigment epithelial cells derived from human iPS cells (hiPSC-RPE).Methods: In KCNJ13 KO and wild-type hiPSC-RPE cells, ZO-1 immunofluorescence was performed, and confocal images were captured. The area and perimeter of each cell were measured. To detect cell death, ethidium homodimer III (EthD-III) staining and LDH assay were used. Scanning electron microscopy (SEM) was used to observe the cell surface. The expression levels of oxidative stress-related genes were examined by quantitative PCR. To explore the effects of oxidative stress, tert-butyl hydroperoxide (t-BHP) was administered to the hiPSC-RPE cells. Cell viability was tested by MTS assay, whereas oxidative damage was monitored by oxidized (GSSG) and reduced glutathione levels.
Results: The area and perimeter of KCNJ13-KO hiPSC-RPE cells were enlarged. EthD-III-positive cells were increased with more dead cells in the protruded region. The KO RPE had significantly higher LDH levels in the medium. SEM observations revealed aggregated cells having broken cell surfaces on the KO RPE sheet. The KCNJ13-deficient RPE showed increased expression levels of oxidative stress-related genes and total glutathione levels. Furthermore, t-BHP induced a significant increase in cell death and GSSG levels in the KO RPE.
Conclusions: We suggest that in the absence of the Kir.7.1 potassium channel, human RPE cells are vulnerable to oxidative stress and ultimately die. The dying/dead cells form aggregates and protrude from the surviving KCNJ13-deficient RPE sheet.

DOI: https://doi.org/10.1167/iovs.63.12.29
Curr Issues Mol Biol. 2022 Nov 21. 44(11): 5788-5801

RIP140-Mediated NF-κB Inflammatory Pathway Promotes Metabolic Dysregulation in Retinal Pigment Epithelium Cells.

Zeli Guo, Yuli Shen, Jianwen Zhong, Zhuoyun Li, Qi Guo, Xiangchao Yao, Yandong Wang, Wenyu Wu.

  Metabolic dysregulation of the retinal pigment epithelium (RPE) has been implicated in age-related macular degeneration (AMD). However, the molecular regulation of RPE metabolism remains unclear. RIP140 is known to affect oxidative metabolism and mitochondrial biogenesis by negatively controlling mitochondrial pathways regulated by PPAR-γ co-activator-1 α(PGC-1α). This study aims to disclose the effect of RIP140 on the RPE metabolic program in vitro and in vivo. RIP140 protein levels were assayed by Western blotting. Gene expression was tested using quantitative real-time PCR (qRT-PCR), ATP production, and glycogen concentration assays, and the release of inflammatory factors was analyzed by commercial kits. Mice photoreceptor function was measured by electroretinography (ERG). In ARPE-19 cells, RIP140 overexpression changed the expression of the key metabolic genes and lipid processing genes, inhibited mitochondrial ATP production, and enhanced glycogenesis. Moreover, RIP140 overexpression promoted the translocation of NF-κB and increased the expression and production of IL-1β, IL-6, and TNF-α in ARPE-19 cells. Importantly, we also observed the overexpression of RIP140 through adenovirus delivery in rat retinal cells, which significantly decreased the amplitude of the a-wave and b-wave measured by ERG assay. Therapeutic strategies that modulate the activity of RIP140 could have clinical utility for the treatment of AMD in terms of preventing RPE degeneration.

Keywords:  NF-κB; RIP140; age-related macular degeneration; inflammation; metabolism

DOI:  https://doi.org/10.3390/cimb44110393
Front Aging Neurosci. 2022 ;14 1016293

Intercellular communication analysis of the human retinal pigment epithelial and choroidal cells predicts pathways associated with aging, cellular senescence and age-related macular degeneration.

Dhanach Dhirachaikulpanich, Cyril Lagger, Kasit Chatsirisupachai, João Pedro de Magalhães, Luminita Paraoan.

  The retinal pigment epithelium (RPE) and the choroid are ocular tissues with fundamental roles in supporting neuroretinal function. The pathogenesis of age-related macular degeneration (AMD), a leading cause of irreversible blindness for which aging is the highest risk factor is closely linked with progressive impairment of various functions of these tissues. Cellular senescence, marked by cell cycle arrest and secretion of proinflammatory factors, is known to be associated with aging and has been proposed as a potential driver of AMD. Here, we investigated the role played by intercellular communication in the RPE/choroid within the context of aging, senescence and AMD. We inferred cell-cell interactions in the RPE/choroid by applying CellChat and scDiffCom on a publicly available scRNA-seq dataset from three human donors with and without AMD. We identified age-regulated ligand and receptor genes by using limma on a separate publicly available bulk microarray dataset providing RPE/choroid samples at multiple time points. Cellular senescence was investigated by assigning a score to each cell and each sample of these scRNA-seq and microarray datasets, respectively, based on the expression of key signature genes determined by a previous senescence meta-analysis. We identified VEGF-, BMP-and tenascin-mediated pathways supporting some of the strongest cell-cell interactions between RPE cells, fibroblasts and choroidal endothelial cells and as strong intercellular communication pathways related to both aging and senescence. Their signaling strength was enhanced between subpopulations of cells having high senescence scores. Predominant ligands of these pathways were upregulated with age whereas predominant receptors were downregulated. Globally, we also observed that cells from AMD samples presented slightly bigger senescence scores than normal cells and that the senescence score positively correlated with age in bulk samples (R = 0.26, value of p < 0.01). Hence, our analysis provides novel information on RPE/choroid intercellular communication that gives insights into the connection between aging, senescence and AMD.

Keywords:  AMD; BMP; RPE; VEGF; aging; choroid; senescence; tenascin

DOI:  https://doi.org/10.3389/fnagi.2022.1016293
Cells. 2022 Nov 09. pii: 3535. [Epub ahead of print]11(22):

Microglia-Neutrophil Interactions Drive Dry AMD-like Pathology in a Mouse Model.

Maeve Boyce, Ying Xin, Olivia Chowdhury, Peng Shang, Haitao Liu, Victoria Koontz, Anastasia Strizhakova, Mihir Nemani, Stacey Hose, J Samuel Zigler, Matthew Campbell, Debasish Sinha, James T Handa, Kai Kaarniranta, Jiang Qian, Sayan Ghosh.

  In dry age-related macular degeneration (AMD), inflammation plays a key role in disease pathogenesis. Innate immune cells such as microglia and neutrophils infiltrate the sub-retinal space (SRS) to induce chronic inflammation and AMD progression. But a major gap in our understanding is how these cells interact with each other in AMD. Here, we report a novel concept of how dynamic interactions between microglia and neutrophils contribute to AMD pathology. Using well-characterized genetically engineered mouse models as tools, we show that in the diseased state, retinal pigmented epithelial (RPE) cells trigger pro-inflammatory (M1) transition in microglia with diminished expression of the homeostatic marker, CX3CR1. Activated microglia localize to the SRS and regulate local neutrophil function, triggering their activation and thereby inducing early RPE changes. Ligand receptor (LR)-loop analysis and cell culture studies revealed that M1 microglia also induce the expression of neutrophil adhesion mediators (integrin β1/α4) through their interaction with CD14 on microglia. Furthermore, microglia-induced neutrophil activation and subsequent neutrophil-mediated RPE alterations were mitigated by inhibiting Akt2 in microglia. These results suggest that the Akt2 pathway in microglia drives M1 microglia-mediated neutrophil activation, thereby triggering early RPE degeneration and is a novel therapeutic target for early AMD, a stage without treatment options.

Keywords:  Akt2; CD14; LR-loop; age-related macular degeneration; chronic inflammation; integrin α4; integrin β1; microglia; neutrophils; retinal pigmented epithelial cells

DOI:  https://doi.org/10.3390/cells11223535
Biomolecules. 2022 Nov 11. pii: 1671. [Epub ahead of print]12(11):

cGMP Signaling in the Neurovascular Unit-Implications for Retinal Ganglion Cell Survival in Glaucoma.

Ameer A Haider, Tonia S Rex, Lauren K Wareham.

  Glaucoma is a progressive age-related disease of the visual system and the leading cause of irreversible blindness worldwide. Currently, intraocular pressure (IOP) is the only modifiable risk factor for the disease, but even as IOP is lowered, the pathology of the disease often progresses. Hence, effective clinical targets for the treatment of glaucoma remain elusive. Glaucoma shares comorbidities with a multitude of vascular diseases, and evidence in humans and animal models demonstrates an association between vascular dysfunction of the retina and glaucoma pathology. Integral to the survival of retinal ganglion cells (RGCs) is functional neurovascular coupling (NVC), providing RGCs with metabolic support in response to neuronal activity. NVC is mediated by cells of the neurovascular unit (NVU), which include vascular cells, glial cells, and neurons. Nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling is a prime mediator of NVC between endothelial cells and neurons, but emerging evidence suggests that cGMP signaling is also important in the physiology of other cells of the NVU. NO-cGMP signaling has been implicated in glaucomatous neurodegeneration in humans and mice. In this review, we explore the role of cGMP signaling in the different cell types of the NVU and investigate the potential links between cGMP signaling, breakdown of neurovascular function, and glaucoma pathology.

Keywords:  endothelial cell; glaucoma; glia; neurodegeneration; neurovascular coupling; neurovascular unit; retina

DOI:  https://doi.org/10.3390/biom12111671
Cells. 2022 Nov 09. pii: 3542. [Epub ahead of print]11(22):

Changes in Mitochondrial Size and Morphology in the RPE and Photoreceptors of the Developing and Ageing Zebrafish.

Thomas Burgoyne, Maria Toms, Chris Way, Dhani Tracey-White, Clare E Futter, Mariya Moosajee.

  Mitochondria are essential adenosine triphosphate (ATP)-generating cellular organelles. In the retina, they are highly numerous in the photoreceptors and retinal pigment epithelium (RPE) due to their high energetic requirements. Fission and fusion of the mitochondria within these cells allow them to adapt to changing demands over the lifespan of the organism. Using transmission electron microscopy, we examined the mitochondrial ultrastructure of zebrafish photoreceptors and RPE from 5 days post fertilisation (dpf) through to late adulthood (3 years). Notably, mitochondria in the youngest animals were large and irregular shaped with a loose cristae architecture, but by 8 dpf they had reduced in size and expanded in number with more defined cristae. Investigation of temporal gene expression of several mitochondrial-related markers indicated fission as the dominant mechanism contributing to the changes observed over time. This is likely to be due to continued mitochondrial stress resulting from the oxidative environment of the retina and prolonged light exposure. We have characterised retinal mitochondrial ageing in a key vertebrate model organism, that provides a basis for future studies of retinal diseases that are linked to mitochondrial dysfunction.

Keywords:  ageing; mitochondria; retina; zebrafish

DOI:  https://doi.org/10.3390/cells11223542
Redox Biol. 2022 Nov 15. pii: S2213-2317(22)00313-5. [Epub ahead of print]58 102541

Inhibition of ferroptosis promotes retina ganglion cell survival in experimental optic neuropathies.

Miao Guo, Yanfang Zhu, Ying Shi, Xiangda Meng, Xue Dong, Haokun Zhang, Xiaohong Wang, Mei Du, Hua Yan.

  Retinal ganglion cell (RGC) death is a hallmark of traumatic optic neuropathy, glaucoma, and other optic neuropathies that result in irreversible vision loss. However, therapeutic strategies for rescuing RGC loss still remain challenging, and the molecular mechanism underlying RGC loss has not been fully elucidated. Here, we highlight the role of ferroptosis, a non-apoptotic form of programmed cell death characterized by iron-dependent lethal lipid peroxides accumulation, in RGC death using an experimental model of glaucoma and optic nerve crush (ONC). ONC treatment resulted in significant downregulation of glutathione peroxidase 4 (GPx4) and system xc(-) cystine/glutamate antiporter (xCT) in the rat retina, accompanied by increased lipid peroxide and iron levels. The reduction of GPx4 expression in RGCs after ONC was confirmed by laser-capture microdissection and PCR. Transmission electron microscopy (TEM) revealed alterations in mitochondrial morphology, including increased membrane density and reduced mitochondrial cristae in RGCs after ONC. Notably, the ferroptosis inhibitor ferrostatin-1 (Fer-1) significantly promoted RGC survival and preserved retinal function in ONC and microbead-induced glaucoma mouse models. In addition, compared to the apoptosis inhibitor Z-VAD-FMK, Fer-1 showed better effect in rescuing RGCs death in ONC retinas. Mechanistically, we found the downregulation of GPx4 mainly occurred in the mitochondrial compartment, accompanied by increased mitochondrial reactive oxygen species (ROS) and lipid peroxides. The mitochondria-selective antioxidant MitoTEMPO attenuated RGC loss after ONC, implicating mitochondrial ROS and lipid peroxides as major mechanisms in ferroptosis-induced RGC death in ONC retinas. Notably, administering Fer-1 effectively prevented the production of mitochondrial lipid peroxides, the impairment of mitochondrial adenosine 5'-triphosphate (ATP) production, and the downregulation of mitochondrial genes, such as mt-Cytb and MT-ATP6, in ONC retinas. Our findings suggest that ferroptosis is a major form of regulated cell death for RGCs in experimental glaucoma and ONC models and suggesting targeting mitochondria-dependent ferroptosis as a protective strategy for RGC injuries in optic neuropathies.

Keywords:  Ferroptosis; Glutathione peroxidase 4; Mitochondrial ROS; Optic neuropathies; Retinal ganglion cells

DOI:  https://doi.org/10.1016/j.redox.2022.102541