bims-mideyd 2022-06-12 papers

Issue of 2022‒06‒12
five papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Biomed Res Int. 2022 ;2022 6180349

Mitochondrial-Targeted Antioxidant Peptide SS31 Prevents RPE Cell Death under Oxidative Stress.

Yuan He, Zejun Chen, Ruixue Zhang, Zhuoya Quan, Yun Xu, Beilei He, Yuan Ren.

This work aims at investigating the protective effects of the mitochondria-targeted peptide SS31, on mitochondria function, preventing human retinal pigment epithelial cell-19 (ARPE-19) cell apoptosis. The ARPE-19 cells were subjected to 24 h of intervention with H2O2 of various concentrations (0, 100, 150, 200, 250, 300, and 500 μmol/L). Various concentrations of SS31 (10 nM, 100 nM, and 1 μmol/L) pretreated the cells for 2 h. The MTT assay determined cell viability. ARPE-19 cell apoptosis was observed by 4',6-diamidino-2-phenylindole (DAPI) staining under fluorescence microscope and detected by Annexin-V/PI staining under flow cytometry. The measurement of reactive oxygen species (ROS) release level used MitoSOX Red (a mitochondrial superoxide indicator) and the probe 2'-7'dichlorofluorescin diacetate (DCFH-DA). And with the use of a JC-1 probe, the mitochondrial membrane potential (MMP; ΔΨm) was analyzed. Reverse transcription polymerase chain reaction (RT-PCR) and real-time PCR were responsible for measuring the levels of apoptosis related genes (Bcl-2, Bax, and Caspase-3). The cell viability increased significantly with SS31 pretreated (P < 0.05). In the SS31 + H2O2 group, the fluorescence of the cell nuclei with DAPI staining was weaker than H2O2 along group accordance with the decreased ratio of apoptotic cells (P < 0.05). The ROS generation decreased in SS31 pretreated group, with the increased ΔΨm. The RT-PCR result showed decreased Bax gene and Caspase-3 gene expression with SS31 pretreatment, while increased antiapoptotic gene Bcl-2 (P < 0.05). We provide evidence that SS31 promotes resilience of RPE cells to oxidative stress by stabilizing mitochondrial function.

DOI: https://doi.org/10.1155/2022/6180349

Cutan Ocul Toxicol. 2022 Jun 05. 1-8

Inhibition of galectin-3 ameliorates high-glucose-induced oxidative stress and inflammation in ARPE-19 cells.

Min Li, Meimei Tian, Xinli Jiang, Yan Liu, Yan Wang, Yukun Li.

PURPOSE: Retinal pigment epithelium (RPE) has been found to be participated in the pathogenesis of DR in recent years. Galectin-3 (Gal-3) is involved in many diabetic complications and ophthalmological diseases. However, the role of Gal-3 in RPE cells in DR remains unknown. This study aims to investigate the role of Gal-3 in ARPE-19 cells under high glucose treatment.MATERIALS AND METHODS: ARPE-19 cells were cultured under normal or high glucose (HG) for 48 h. Expression of Gal-3 was inhibited by Si-Gal-3 transfection. Apoptosis was checked by flow cytometry. Oxidative stress was checked by measuring ROS, MDA levels, and SOD activities. Occludin and ZO-1 expression were checked by immunofluorescence staining. Genes involved in inflammatory response were measured by real-time PCR and Western blot.
RESULTS: Gal-3 expression could be increased by HG treatment in ARPE-19 cells. Gal-3 knockdown might reduce oxidative stress, apoptosis, and gene expression of VCAM-1, ICAM-1, and integrin-β1 induced by HG treatment. The gene expression of IL-1β could be markedly promoted by HG treatment and this increasement was partly alleviated by Gal-3 knockdown only at the mRNA level. The reduced expression of ZO-1 and occludin caused by HG could also be improved by Gal-3 knockdown.
CONCLUSION: Gal-3 participated in increased oxidative stress and inflammatory response caused by HG in ARPE-19 cells.

Keywords: Retinal pigment epithelia; galectin-3; hyperglycaemia; inflammation; oxidative stress

DOI: https://doi.org/10.1080/15569527.2022.2081701

Immunol Res. 2022 Jun 04.

Hydroquinone predisposes for retinal pigment epithelial (RPE) cell degeneration in inflammatory conditions.

Niina Bhattarai, Maria Hytti, Mika Reinisalo, Kai Kaarniranta, Yashavanthi Mysore, Anu Kauppinen.

In addition to hypoxia, inflammation is capable of inducing vascular endothelial growth factor (VEGF) expression in human retinal pigment epithelial (RPE) cells. Excessive levels of VEGF promote choroidal neovascularization and thereby contribute to the pathogenesis of wet age-related macular degeneration (AMD). Intravitreal anti-VEGF injections ameliorate pathological vessel neoformation in wet AMD but excessive dampening of VEGF can result in a degeneration of the RPE. In the present study, we induced VEGF production by exposing human ARPE-19 cells to the pro-inflammatory IL-1α and subsequently to hydroquinone, a component of tobacco smoke that is a major environmental risk factor for AMD. Effects were monitored by measuring the levels of VEGF and anti-angiogenic pigment epithelium-derived factor (PEDF) using an enzyme-linked immunosorbent assay (ELISA) technique. In addition, we measured the production of reactive oxygen species (ROS) using the 2',7'-dichlorofluorescin diacetate (H2DCFDA) probe and studied the effects of two anti-oxidants, ammonium pyrrolidinedithiocarbamate (APDC) and N-acetyl-cysteine (NAC), on VEGF production. Cellular and secreted VEGF as well as secreted PEDF levels were reduced at all tested hydroquinone concentrations (10, 50, or 200 µM); these effects were evident prior to any reduction of cell viability evoked by hydroquinone. Cell viability was carefully explored in our previous study and verified by microscoping in the present study. APDC further reduced the VEGF levels, whereas NAC increased them. The 50 μM concentration of hydroquinone increased ROS production in ARPE-19 cells primed with IL-1α. Hydroquinone disturbs the regulatory balance of VEGF and PEDF in inflammatory conditions. These data support the idea that hydroquinone mediates RPE degeneration by reducing VEGF levels and may predispose to dry AMD since VEGF is as well important for retinal integrity.

Keywords: ARPE-19; Antioxidants; Hydroquinone; IL-1α; PEDF; ROS; VEGF

DOI: https://doi.org/10.1007/s12026-022-09300-0

Transpl Immunol. 2022 May 31. pii: S0966-3274(22)00110-1. [Epub ahead of print]73 101636

Hyperglycemia induces retinal ganglion cell endoplasmic reticulum stress to the involvement of glaucoma in diabetic mice.

Jinzi Zhou, Fenghua Chen, Aimin Yan, Jian Jiang, Xiaobo Xia.

Glaucoma is a neurodegenerative disease leading to visual loss. Since glaucoma is associated with chronic renal diseases (RDs) their rate is higher in patients with RDs, and end-stage RDs (ESRDs) than in the general population and kidney transplant recipients.OBJECTIVE: To explore the molecular mechanism of diabetic internal environment in regulating the endoplasmic reticulum stress of the retinal ganglion cells (RGCs).
METHODS: Thirty-six SPF grade type 2 diabetes models were divided into 3 groups: Diabetes mellitus (DM), DM + glaucoma and 4-phenylbutyric acid-DM (4-PBA-DM) + glaucoma group. C57BL6 mice of the same week age were taken as the negative control (NC) group. The morphology of RGCs and their axon in the 4 groups were labeled by fluorescent reactive dye Dil. The apoptosis situation of RGCs was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. The protein expression values of RTN4IP1, Protein kinase R-like endoplasmic reticulum kinase (PERK), eukaryotic initiation factor 2A (eIF2a) and X-box-binding Protein 1 (XBP1) were determined by western blot. The relative mRNA levels of cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP), Caspase12 and Bax were determined by quantitative real-time polymerase chain reaction (qRT-PCR).
RESULTS: Glaucoma promotes the apoptosis of RGCs. The protein expression values of RTN4IP1, PERK and XBP1 in DM mouse models with glaucoma were much higher compared to only DM mouse models. Further injection of endoplasmic reticulum stress inhibitor 4-PBA decreased the expression values. The relative mRNA levels of CHOP, Cysteine aspartic acid specific protease12 (Caspase12) and BCL2-associated X protein (Bax) in DM + glaucoma were significantly higher compared to those in DM group. Further injection of endoplasmic reticulum stress inhibitor 4-PBA decreased the mRNA levels.
CONCLUSION: Endoplasmic reticulum stress (ERS) is the underlying cause of glaucoma, which could promote the apoptosis of RGCs in diabetic mice.

Keywords: Endoplasmic reticulum stress; Glaucoma; Intraocular pressure; Retinal ganglion cells

DOI: https://doi.org/10.1016/j.trim.2022.101636

FASEB J. 2022 Jul;36(7): e22397

Inhibition of Rho-associated protein kinase activity enhances oxidative phosphorylation to support corneal endothelial cell migration.

Wei-Ting Ho, Jung-Shen Chang, Tsan-Chi Chen, Jia-Kang Wang, Shu-Wen Chang, Muh-Hwa Yang, Tzuu-Shuh Jou, I-Jong Wang.

Corneal endothelial cell (CEC) dysfunction causes corneal edema and severe visual impairment that require transplantation to restore vision. To address the unmet need of organ shortage, descemetorhexis without endothelial keratoplasty has been specifically employed to treat early stage Fuchs endothelial corneal dystrophy, which is pathophysiologically related to oxidative stress and exhibits centrally located corneal guttae. After stripping off central Descemet's membrane, rho-associated protein kinase (ROCK) inhibitor has been found to facilitate CEC migration, an energy-demanding task, thereby achieving wound closure. However, the correlation between ROCK inhibition and the change in bioenergetic status of CECs remained to be elucidated. Through transcriptomic profiling, we found that the inhibition of ROCK activity by the selective inhibitor, ripasudil or Y27632, promoted enrichment of oxidative phosphorylation (OXPHOS) gene set in bovine CECs (BCECs). Functional analysis revealed that ripasudil, a clinically approved anti-glaucoma agent, enhanced mitochondrial respiration, increased spare respiratory capacity, and induced overexpression of electron transport chain components through upregulation of AMP-activated protein kinase (AMPK) pathway. Accelerated BCEC migration and in vitro wound healing by ripasudil were diminished by OXPHOS and AMPK inhibition, but not by glycolysis inhibition. Correspondingly, lamellipodial protrusion and actin assembly that were augmented by ripasudil became reduced with additional OXPHOS or AMPK inhibition. These results indicate that ROCK inhibition induces metabolic reprogramming toward OXPHOS to support migration of CECs.

Keywords: AMP-activated protein kinase; cell migration; corneal endothelial cell; mitochondria; oxidative phosphorylation; rho-associated protein kinase

DOI: https://doi.org/10.1096/fj.202101442RR