bims-mideyd 2023-10-08 papers

bims-mideyd

Biomed News

on Mitochondrial dysfunction in eye diseases

Issue of 2023–10–08
nine papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

An In Vitro Bilayer Model of Human Primary Retinal Pigment Epithelial and Choroid Endothelial Cells for Permeability Studies.
EZH2 Promotes Corneal Endothelial Cell Apoptosis by Mediating H3K27me3 and Inhibiting HO-1 Transcription.
Gene expression signatures of human senescent corneal and conjunctival epithelial cells.
Mitochondrial dysfunction: A fatal blow in depression.
The glyoxylate shunt protein ICL-1 protects from mitochondrial superoxide stress through activation of the mitochondrial unfolded protein response.
Protective effect of ethyl ferulate against hypoxic injury in retinal cells and retinal neovascularization in an oxygen-induced retinopathy model.
Human Neural Progenitors Expressing GDNF Enhance Retinal Protection in a Rodent Model of Retinal Degeneration.
Effect of Cannabidiol in LPS-Induced Toxicity in Astrocytes: Possible Role for Cannabinoid Type-1 Receptors.
Melatonin prevents EAAC1 deletion-induced retinal ganglion cell degeneration by inhibiting apoptosis and senescence.

Methods Mol Biol. 2024 ;2711 205-223

An In Vitro Bilayer Model of Human Primary Retinal Pigment Epithelial and Choroid Endothelial Cells for Permeability Studies.

Karthikka Palanisamy, Subbulakshmi Chidambaram.

  The blood-retinal barrier (BRB) present in the posterior chamber of the eye plays a major role in maintaining the proper function and integrity of the retina. Retinal pigment epithelium and choriocapillaris form the outer blood retinal barrier (oBRB), and breakdown of this barrier leads to vision-threatening diseases like macular edema, macular degeneration, and diabetic retinopathy. A simplified cell culture model of oBRB will be of great importance in elucidating the molecular mechanism of the disease progression. This chapter describes methods for primary cell isolation from donor eyes to culture human retinal pigment epithelial cells (hRPE) and choroidal endothelial cells (hCEC) and the protocol for construction of a simplified in vitro model of oBRB on fibronectin-coated Transwell inserts. Further, we explained the permeability study using FITC-dextran conjugated tracers for validating the bilayer model. The permeability experiments ensured that the system could easily be manipulated to recapitulate the pathological condition in vitro. Thus, it would be an optimal system for studying the disease mechanisms related to retinal and choroidal pathologies, for screening small molecules, and for performing drug permeability kinetics. Moreover, fundamental understanding of paracellular and transcellular trafficking of cargo in hRPE and hCEC could also be studied using this model.

Keywords:  Donor eyes; FITC dextran permeability assay; Human primary choroidal endothelial cells; Human retinal pigment epithelial cells; In vitro blood retinal barrier model; Transwell inserts

DOI:  https://doi.org/10.1007/978-1-0716-3429-5_17
Curr Eye Res. 2023 Oct 06. 1-11

EZH2 Promotes Corneal Endothelial Cell Apoptosis by Mediating H3K27me3 and Inhibiting HO-1 Transcription.

Ying Lin, Huanjun Su, Baoyi Zou, Minli Huang.

   PURPOSE: This paper aims to explore the molecular mechanism of Enhancer of Zeste Homolog 2 (EZH2)-mediated H3K27me3 in human corneal endothelial cells (HCEC) apoptosis by inhibiting Heme oxygenase-1 (HO-1) transcription to provide a potential target for the treatment of corneal apoptosis.
METHODS: HCECs were cultured in vitro and transfected with si-EZH2, pcDNA3.1-EZH2, pcDNA3.1-HO-1, GSK-J4 (an effective H3K27me3 demethylase inhibitor), and corresponding controls. Western Blot assay was used to detect the levels of EZH2, HO-1, H3K27me3, and apoptosis-related proteins (Bcl-2, Bax, and Cleaved-caspase-3) in HCECs; CCK-8 assay was conducted to detect cell viability and flow cytometry to analyze the apoptosis. HO-1 mRNA levels were detected by RT-qPCR and changes in H3K27me3 levels on the HO-1 promoter were detected by chromatin immunoprecipitation.
RESULTS: HCECs transfected with si-EZH2 showed significantly lower EZH2 mRNA and protein levels, higher HCEC viability, lower apoptosis rates, higher antiapoptotic protein Bcl-2 expression, lower proapoptotic protein (Bax and Cleaved-caspase-3) levels, and significantly higher HO-1 expression. HCECs transfected with pcDNA3.1-EZH2 showed the opposite results. EZH2 repressed HO-1 transcription by mediating H3K27me3. H3K27me27 was enriched in the HO-1 promoter and overexpression of EZH2 increased H3K27me27 levels. Promotion of H3K27me3 partially reversed the mitigating effect of si-EZH2 on HCEC apoptosis. Overexpression of HO-1 partially reversed the apoptosis-promoting effects of EZH2 and H3K27me3 on HCECs.
CONCLUSIONS: EZH2 promotes HCE cell apoptosis by mediating H3K27me3 to inhibit HO-1 transcription.

Keywords:  Enhancer of zeste homolog 2; H3K27me3; apoptosis; heme oxygenase-1; human corneal endothelial cells

DOI:  https://doi.org/10.1080/02713683.2023.2257401
Aging (Albany NY). 2023 Sep 28. 15(18): 9238-9249

Gene expression signatures of human senescent corneal and conjunctival epithelial cells.

Koji Kitazawa, Akifumi Matsumoto, Kohsaku Numa, Yasufumi Tomioka, Zhixin A Zhang, Yohei Yamashita, Chie Sotozono, Pierre-Yves Desprez, Judith Campisi.

   PURPOSE: This study aimed to investigate the senescent phenotypes of human corneal and conjunctival epithelial cells.
METHODS: We examined cell morphology, senescence-associated β-galactosidase (SA-β-gal) activity, cell proliferation, and expression of senescence markers (p16 and p21). RNA sequencing analysis was conducted to compare gene expression profiles between senescent and non-senescent cells. Finally, the potential involvement of senescent cells in the pathogenesis of ocular surface diseases was investigated.
RESULTS: X-irradiated corneal and conjunctival epithelial cells exhibited typical senescence phenotypes, i.e., flattened morphologies, increased SA-β-gal activity, decreased cell proliferation, and increased expression of senescence markers, p16 and p21. RNA-seq analysis revealed substantial differences in gene expression profiles between senescent corneal (SCo) and conjunctival epithelial cells (SCj). Moreover, SCj were detected in pathological conjunctival tissues associated with limbal stem cell deficiency (LSCD) due to Stevens-Johnson syndrome or chemical burns, potentially being involved in abnormal differentiation.
CONCLUSION: This study highlights the cellular and molecular characteristics of senescent ocular surface cells, particularly in SCj that show abnormal keratin expression, and their potential roles in severe ocular surface diseases and pathology.

Keywords:  Stevens-Johnson syndrome; cellular senescence; conjunctiva; cornea; limbal stem cell deficiency

DOI:  https://doi.org/10.18632/aging.205113
Biomed Pharmacother. 2023 Oct 04. pii: S0753-3322(23)01450-6. [Epub ahead of print]167 115652

Mitochondrial dysfunction: A fatal blow in depression.

Yu Song, Huan Cao, Chengchao Zuo, Zhongya Gu, Yaqi Huang, Jinfeng Miao, Yufeng Fu, Yu Guo, Yongsheng Jiang, Furong Wang.

  Mitochondria maintain the normal physiological function of nerve cells by producing sufficient cellular energy and performing crucial roles in maintaining the metabolic balance through intracellular Ca2+ homeostasis, oxidative stress, and axonal development. Depression is a prevalent psychiatric disorder with an unclear pathophysiology. Damage to the hippocampal neurons is a key component of the plasticity regulation of synapses and plays a critical role in the mechanism of depression. There is evidence suggesting that mitochondrial dysfunction is associated with synaptic impairment. The maintenance of mitochondrial homeostasis includes quantitative maintenance and quality control of mitochondria. Mitochondrial biogenesis produces new and healthy mitochondria, and mitochondrial dynamics cooperates with mitophagy to remove damaged mitochondria. These processes maintain mitochondrial population stability and exert neuroprotective effects against early depression. In contrast, mitochondrial dysfunction is observed in various brain regions of patients with major depressive disorders. The accumulation of defective mitochondria accelerates cellular nerve dysfunction. In addition, impaired mitochondria aggravate alterations in the brain microenvironment, promoting neuroinflammation and energy depletion, thereby exacerbating the development of depression. This review summarizes the influence of mitochondrial dysfunction and the underlying molecular pathways on the pathogenesis of depression. Additionally, we discuss the maintenance of mitochondrial homeostasis as a potential therapeutic strategy for depression.

Keywords:  Major depressive disorder; Mitochondrial dysfunction; Mitochondrial quality control; Neuroinflammation

DOI:  https://doi.org/10.1016/j.biopha.2023.115652
Free Radic Biol Med. 2023 Sep 25. pii: S0891-5849(23)00654-8. [Epub ahead of print]208 771-779

The glyoxylate shunt protein ICL-1 protects from mitochondrial superoxide stress through activation of the mitochondrial unfolded protein response.

Guoqiang Wang, Ricardo Laranjeiro, Stephanie LeValley, Jeremy M Van Raamsdonk, Monica Driscoll.

Disrupting mitochondrial superoxide dismutase (SOD) causes neonatal lethality in mice and death of flies within 24 h after eclosion. Deletion of mitochondrial sod genes in C. elegans impairs fertility as well, but surprisingly is not detrimental to survival of progeny generated. The comparison of metabolic pathways among mouse, flies and nematodes reveals that mice and flies lack the glyoxylate shunt, a shortcut that bypasses part of the tricarboxylic acid (TCA) cycle. Here we show that ICL-1, the sole protein that catalyzes the glyoxylate shunt, is critical for protection against embryonic lethality resulting from elevated levels of mitochondrial superoxide. In exploring the mechanism by which ICL-1 protects against ROS-mediated embryonic lethality, we find that ICL-1 is required for the efficient activation of mitochondrial unfolded protein response (UPRmt) and that ATFS-1, a key UPRmt transcription factor and an activator of icl-1 gene expression, is essential to limit embryonic/neonatal lethality in animals lacking mitochondrial SOD. In sum, we identify a biochemical pathway that highlights a molecular strategy for combating toxic mitochondrial superoxide consequences in cells.

DOI: https://doi.org/10.1016/j.freeradbiomed.2023.09.029
Phytomedicine. 2023 Sep 20. pii: S0944-7113(23)00457-9. [Epub ahead of print]121 155097

Protective effect of ethyl ferulate against hypoxic injury in retinal cells and retinal neovascularization in an oxygen-induced retinopathy model.

Rong Xue, Xia-Lian Fan, Qian Yang, Chuan Yu, Tai-Ying Lu, Guang-Ming Wan.

   BACKGROUND: Pathological neovascularization is a major cause of visual impairment in hypoxia-induced retinopathy. Ethyl ferulate (EF), the natural ester derivative of ferulic acid commonly found in Ferula and Angelica Sinensis, has been shown to exert antioxidant, neuroprotective, and anti-inflammatory properties. However, whether EF exerts a protective effect on retinal neovascularization and the underlying mechanisms are not well known.
PURPOSE: The aim of the study was to investigate the effect of EF on retinal neovascularization and explore its underlying molecular mechanisms.
STUDY-DESIGN/METHODS: We constructed hypoxia models induced by cobalt chloride (CoCl2) in ARPE-19 cells and Rhesus choroid-retinal vascular endothelial (RF/6A) cells in vitro, as well as a retinal neovascularization model in oxygen-induced retinopathy (OIR) mice in vivo.
RESULTS: In this work, we demonstrated that EF treatment inhibited hypoxia-induced vascular endothelial growth factor A (VEGFA) expression in ARPE-19 cells and abrogated hypoxia-induced tube formation in RF/6A cells. As expected, intravitreal injection of EF significantly suppressed retinal neovascularization in a dose-dependent manner in OIR retinas. We also found that hypoxia increased VEGFA expression by blocking autophagic flux, whereas EF treatment enhanced autophagic flux, thereby reducing VEGFA expression. Furthermore, EF activated the sequestosome 1 (p62) / nuclear factor E2-related factor 2 (Nrf-2) pathway via upregulating oxidative stress-induced growth inhibitor 1 (OSGIN1) expression, thus alleviating oxidative stress and reducing VEGFA expression.
CONCLUSION: As a result of our findings, EF has an inhibitory effect on retinal neovascularization, implying a potential therapeutic strategy for hypoxia-induced retinopathy.

Keywords:  Autophagy; Ethyl ferulate; Hypoxia; Nrf-2; Retinal neovascularization

DOI:  https://doi.org/10.1016/j.phymed.2023.155097
Stem Cells Transl Med. 2023 Oct 03. pii: szad054. [Epub ahead of print]

Human Neural Progenitors Expressing GDNF Enhance Retinal Protection in a Rodent Model of Retinal Degeneration.

Saba Shahin, Patrick Tan, Jason Chetsawang, Bin Lu, Soshana Svendsen, Stephany Ramirez, Trevor Conniff, Jorge S Alfaro, Michael Fernandez, Aaron Fulton, Alexander H Laperle, Clive N Svendsen, Shaomei Wang.

  Stem cell therapy for retinal degenerative diseases has been extensively tested in preclinical and clinical studies. However, preclinical studies performed in animal models at the early stage of disease do not optimally translate to patients that present to the clinic at a later stage of disease. As the retina degenerates, inflammation and oxidative stress increase and trophic factor support declines. Testing stem cell therapies in animal models at a clinically relevant stage is critical for translation to the clinic. Human neural progenitor cells (hNPC) and hNPC engineered to stably express GDNF (hNPCGDNF) were subretinally injected into the Royal College of Surgeon (RCS) rats, a well-established model for retinal degeneration, at early and later stages of the disease. hNPCGDNF treatment at the early stage of retinal degeneration provided enhanced visual function compared to hNPC alone. Treatment with both cell types resulted in preserved retinal morphology compared to controls. hNPCGDNF treatment led to significantly broader photoreceptor protection than hNPC treatment at both early and later times of intervention. The phagocytic role of hNPC appears to support RPE cell functions and the secreted GDNF offers neuroprotection and enables the extended survival of photoreceptor cells in transplanted animal eyes. Donor cells in the RCS rat retina survived with only limited proliferation, and hNPCGDNF produced GDNF in vivo. Cell treatment led to significant changes in various pathways related to cell survival, antioxidative stress, phagocytosis, and autophagy. A combined stem cell and trophic factor therapy holds great promise for treating retinal degenerative diseases including retinitis pigmentosa and age-related macular degeneration.

Keywords:  neural progenitors; oxidative stress; retinal degeneration; trophic factors; visual function

DOI:  https://doi.org/10.1093/stcltm/szad054
Neurotox Res. 2023 Oct 02.

Effect of Cannabidiol in LPS-Induced Toxicity in Astrocytes: Possible Role for Cannabinoid Type-1 Receptors.

Hind Ibork, Sara El Idrissi, Simo Siyanda Zulu, Robert Miller, Lhoussain Hajji, Annabelle Manalo Morgan, Khalid Taghzouti, Oualid Abboussi.

  Cerebral metabolic abnormalities are common in neurodegenerative diseases. Previous studies have shown that mitochondrial damage alters ATP production and increases reactive oxygen species (ROS) release which may contribute to neurodegeneration. In the present study, we investigated the neuroprotective effects of cannabidiol (CBD), a non-psychoactive component derived from marijuana (Cannabis sativa L.), on astrocytic bioenergetic balance in a primary cell culture model of lipopolysaccharide (LPS)-induced neurotoxicity. Astrocytic metabolic profiling using an extracellular flux analyzer demonstrated that CBD decreases mitochondrial proton leak, increased spare respiratory capacity and coupling efficiency in LPS-stimulated astrocytes. Simultaneously, CBD increased astrocytic glycolytic capacity and glycolysis reserve in a cannabinoid receptor type 1 (CB1)-dependent manner. CBD-restored metabolic changes were correlated with a significant decrease in the pro-inflammatory cytokines tumor necrosis factor α (TNFα) and interleukin-6 (IL-6) concentration and reduction of ROS production in LPS-stimulated astrocytes. These results suggest that CBD may inhibit LPS-induced metabolic impairments and inflammation by enhancing astrocytic metabolic glycolysis versus oxidative phosphorylation through its action on CB1 receptors. The present findings suggest CBD as a potential anti-inflammatory treatment in metabolic pathologies and highlight a possible role for the cannabinoidergic system in the modulation of mitochondrial oxidative stress. CBD enhances mitochondrial bioenergetic profile, attenuates proinflammatory cytokines release, and ROS overproduction of astrocytes stimulated by LPS. These effects are not mediated directly by CB1 receptors, while these receptors seem to have a key role in the anti-inflammatory response of the endocannabinoid system on astrocytes, as their specific inhibition by SR141716A led to increased pro-inflammatory cytokines release and ROS production. The graphical abstract is created with BioRender.com.

Keywords:  Cannabidiol; Cannabinoid receptor 1; Metabolism; Mitochondrial bioenergetics; Primary astrocytes

DOI:  https://doi.org/10.1007/s12640-023-00671-2
J Pineal Res. 2023 Oct 03. e12916

Melatonin prevents EAAC1 deletion-induced retinal ganglion cell degeneration by inhibiting apoptosis and senescence.

Chenyang Hu, Yanlin Feng, Guangyi Huang, Kaixuan Cui, Matthew Fan, Wu Xiang, Yuxun Shi, Dan Ye, Huiwen Ye, Xue Bai, Fan Xu, Yue Xu, Jingjing Huang.

  Normal tension glaucoma (NTG) is referred to as a progressive degenerative disorder of the retinal ganglion cells (RGCs), resulting in nonreversible visual defects, despite intraocular pressure levels within the statistically normal range. Current therapeutic strategies for NTG yield limited benefits. Excitatory amino acid carrier 1 (EAAC1) knockout (EAAC1-/- ) in mice has been shown to induce RGC degeneration without elevating intraocular pressure, mimicking pathological characteristics of NTG. In this study, we explored whether daily oral administration of melatonin could block RGCs loss and prevent retinal morphology and function defects associated with EAAC1 deletion. We also explored the molecular mechanisms underlying EAAC1 deletion-induced RGC degeneration and the neuroprotective effects of melatonin. Our RNA sequencing and in vivo data indicated EAAC1 deletion caused elevated oxidative stress, activation of apoptosis and cellular senescence pathways, and neuroinflammation in RGCs. However, melatonin administration efficiently prevented these detrimental effects. Furthermore, we investigated the potential role of apoptosis- and senescence-related redox-sensitive factors in EAAC1 deletion-induced RGCs degeneration and the neuroprotective effects of melatonin administration. We observed remarkable upregulation of p53, whereas NRF2 and Sirt1 expression were significantly decreased in EAAC1-/- mice, which were prevented by melatonin treatment, suggesting that melatonin exerted its neuroprotective effects possibly through modulating NRF2/p53/Sirt1 redox-sensitive signaling pathways. Overall, our study provided a solid foundation for the application of melatonin in the management of NTG.

Keywords:  EAAC1; apoptosis; melatonin; normal tension glaucoma; oxidative stress; retinal ganglion cells; senescence

DOI:  https://doi.org/10.1111/jpi.12916