bims-mideyd 2024-04-14 papers

Issue of 2024‒04‒14
five papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Exp Eye Res. 2024 Apr 07. pii: S0014-4835(24)00110-6. [Epub ahead of print]242 109889

Autophagy in dry AMD: A promising therapeutic strategy for retinal pigment epithelial cell damage.

Zhao Zhang, Fengming Liang, Jun Chang, Xiaoqian Shan, Zhixian Yin, Li Wang, Shujiao Li.

Dry age-related macular degeneration (AMD) is a prevalent clinical condition that leads to permanent damage to central vision and poses a significant threat to patients' visual health. Although the pathogenesis of dry AMD remains unclear, there is consensus on the role of retinal pigment epithelium (RPE) damage. Oxidative stress and chronic inflammation are major contributors to RPE cell damage, and the NOD-like receptor thermoprotein structural domain-associated protein 3 (NLRP3) inflammasome mediates the inflammatory response leading to apoptosis in RPE cells. Furthermore, lipofuscin accumulation results in oxidative stress, NLRP3 activation, and the development of vitelliform lesions, a hallmark of dry AMD, all of which may contribute to RPE dysfunction. The process of autophagy, involving the encapsulation, recognition, and transport of accumulated proteins and dead cells to the lysosome for degradation, is recognized as a significant pathway for cellular self-protection and homeostasis maintenance. Recently, RPE cell autophagy has been discovered to be closely linked to the development of macular degeneration, positioning autophagy as a cutting-edge research area in the realm of dry AMD. In this review, we present an overview of how lipofuscin, oxidative stress, and the NLRP3 inflammasome damage the RPE through their respective causal mechanisms. We summarized the connection between autophagy, oxidative stress, and NLRP3 inflammatory cytokines. Our findings suggest that targeting autophagy improves RPE function and sustains visual health, offering new perspectives for understanding the pathogenesis and clinical management of dry AMD.

Keywords: Autophagy; Dry age-related macular degeneration; Lipofuscin; NLRP3 inflammasome; Oxidative stress; mTOR

DOI: https://doi.org/10.1016/j.exer.2024.109889

World J Diabetes. 2024 Mar 15. 15(3): 519-529

Diabetes and high-glucose could upregulate the expression of receptor for activated C kinase 1 in retina.

Jian Tan, Ang Xiao, Lin Yang, Yu-Lin Tao, Yi Shao, Qiong Zhou.

BACKGROUND: Diabetic retinopathy (DR) is a major ocular complication of diabetes mellitus, leading to visual impairment. Retinal pigment epithelium (RPE) injury is a key component of the outer blood retinal barrier, and its damage is an important indicator of DR. Receptor for activated C kinase 1 (RACK1) activates protein kinase C-ε (PKC-ε) to promote the generation of reactive oxygen species (ROS) in RPE cells, leading to apoptosis. Therefore, we hypothesize that the activation of RACK1 under hypoxic/high-glucose conditions may promote RPE cell apoptosis by modulating PKC-ε/ROS, thereby disrupting the barrier effect of the outer blood retinal barrier and contributing to the progression of DR.AIM: To investigate the role and associated underlying mechanisms of RACK1 in the development of early DR.
METHODS: In this study, Sprague-Dawley rats and adult RPE cell line-19 (ARPE-19) cells were used as in vivo and in vitro models, respectively, to explore the role of RACK1 in mediating PKC-ε in early DR. Furthermore, the impact of RACK1 on apoptosis and barrier function of RPE cells was also investigated in the former model.
RESULTS: Streptozotocin-induced diabetic rats showed increased apoptosis and up-regulated expression of RACK1 and PKC-ε proteins in RPE cells following a prolonged modeling. Similarly, ARPE-19 cells exposed to high glucose and hypoxia displayed elevated mRNA and protein levels of RACK1 and PKC-ε, accompanied by an increases in ROS production, apoptosis rate, and monolayer permeability. However, silencing RACK1 significantly downregulated the expression of PKC-ε and ROS, reduced cell apoptosis and permeability, and protected barrier function.
CONCLUSION: RACK1 plays a significant role in the development of early DR and might serve as a potential therapeutic target for DR by regulating RPE apoptosis and barrier function.

Keywords: Adult retinal pigment epithelium cell line-19; Diabetic retinopathy; Protein kinase C-ε; Receptor for activated C kinase 1

DOI: https://doi.org/10.4239/wjd.v15.i3.519

Vision Res. 2024 Apr 08. pii: S0042-6989(24)00032-4. [Epub ahead of print]220 108388

Selective microRNA expression of exosomes from retinal pigment epithelial cells by oxidative stress.

Zhengyu Zhang, Qinyuan Gu, Lu Chen, Dongqing Yuan, Xunyi Gu, Huiming Qian, Ping Xie, Qinghuai Liu, Zizhong Hu.

The function of exosomal miRNAs (miRs) in retinal degeneration is largely unclear. We were aimed to investigate the functions of exosomes as well as their miRs derived from retinal pigment epithelial (RPE) cells following exposure to oxidative stress (OS). After the OS by lipopolysaccharide and rotenone on RPE cells, interleukin-1 beta (IL-1β), Interleukin-6 (IL-6), Tumor Necrosis Factor-alpha (TNF-α) were upregulated, along with the decreased mitochondrial membrane potential and upregulated oxidative damage marker 8-OH-dG in RPE cells. RPE-derived exosomes were then isolated, identified, injected into the subretinal space in mice. After subretinal injection, RPE-exosomes after OS not only induced higher ROS level and apoptotic retinal cells, but also elevated IL-1β, IL-6 alongside TNF-α expressions among retina/RPE/choroidal complex. Next, miRs inside the exosomes were sequenced by the next generation sequencing (NGS) technology. NGS revealed that certain miRs were abundant in exosomes, while others were selectively kept by RPE cells. Further, downregulated miRs, like miR-125b-5p, miR-125a-5p, alongside miR-128-3p, and upregulated miR, such as miR-7-5p were validated byRT-qPCR. Finally, Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to find the possible target genes of those selective exosomal miRs. Our results proved that the RPE-derived exosomes after OS selectively express certain miRs, providing novel insights into the pathogenesis of age-related macular degeneration (AMD) in future.

Keywords: Exosome; Next generation sequencing; Retinal pigment epithelia; Retinopathy; miRNA

DOI: https://doi.org/10.1016/j.visres.2024.108388

Cell Prolif. 2024 Apr 09. e13635

The antioxidant effect of tetrahedral framework nucleic acid-based delivery of small activating RNA targeting DJ-1 on retinal oxidative stress injury.

Qiaowei Wu, Jingyi Zhu, Xianggui Zhang, Xiaoxiao Xu, Delun Luo, Yunfeng Lin, Ming Yan, Yanping Song.

Age-related macular degeneration (AMD) and diabetic retinopathy (DR) are the world's leading causes of blindness. The retinal pigment epithelium (RPE) and vascular endothelial cell exposed to oxidative stress is the major cause of AMD and DR. DJ-1, an important endogenous antioxidant, its overexpression is considered as a promising antioxidant treatment for AMD and DR. Here, we modified the tetrahedral frame nucleic acids (tFNAs) with DJ-1 saRNAs as a delivery system, and synthesized a novel nanocomplex (tFNAs-DJ-1 saRNAs). In vitro studies show that tFNAs-DJ-1 saRNAs can efficiently transfer DJ-1 saRNAs to human umbilical vein endothelial cells (HUVECs) and ARPE-19s, and significantly increased their cellular DJ-1 level. Reactive oxygen species expression in H2O2-treated HUVECs and ARPE-19s were decreased, cell viability was enhanced and cell apoptosis were inhibited when tFNAs-DJ-1 saRNAs were delivered. Moreover, tFNAs-DJ-1 saRNAs preserved mitochondrial structure and function under oxidative stress conditions. In the aspect of molecular mechanism, tFNAs-DJ-1 saRNAs activated Erk and Nrf2 pathway, which might contribute to its protective effects against oxidative stress damage. To conclude, this study shows the successfully establishment of a simple but effective delivery system of DJ-1 saRNAs associated with antioxidant effects in AMD and DR, which may be a promising agent for future treatment in oxidative stress-related retinal disorders.

DOI: https://doi.org/10.1111/cpr.13635

Biomol Ther (Seoul). 2024 Apr 09.

Activation of Heme Oxygenase-1 by Mangiferin in Human Retinal Pigment Epithelial Cells Contributes to Blocking Oxidative Damage.

Cheol Park, Hee-Jae Cha, Hyun Hwangbo, EunJin Bang, Heui-Soo Kim, Seok Joong Yun, Sung-Kwon Moon, Wun-Jae Kim, Gi-Young Kim, Seung-On Lee, Jung-Hyun Shim, Yung Hyun Choi.

Mangiferin is a kind of natural xanthone glycosides and is known to have various pharmacological activities. However, since the beneficial efficacy of this compound has not been reported in retinal pigment epithelial (RPE) cells, this study aimed to evaluate whether mangiferin could protect human RPE ARPE-19 cells from oxidative injury mimicked by hydrogen peroxide (H2O2). The results showed that mangiferin attenuated H2O2-induced cell viability reduction and DNA damage, while inhibiting reactive oxygen species (ROS) production and preserving diminished glutathione (GSH). Mangiferin also antagonized H2O2-induced inhibition of the expression and activity of antioxidant enzymes such as manganese superoxide dismutase and GSH peroxidase, which was associated with inhibition of mitochondrial ROS production. In addition, mangiferin protected ARPE-19 cells from H2O2-induced apoptosis by increasing the Bcl-2/Bax ratio, decreasing caspase-3 activation, and blocking poly(ADP-ribose) polymerase cleavage. Moreover, mangiferin suppressed the release of cytochrome c into the cytosol, which was achieved by interfering with mitochondrial membrane disruption. Furthermore, mangiferin increased the expression and activity of heme oxygenase-1 (HO-1) and nuclear factor-erythroid-2 related factor 2 (Nrf2). However, the inhibition of ROS production, cytoprotective and anti-apoptotic effects of mangiferin were significantly attenuated by the HO-1 inhibitor, indicating that mangiferin promoted Nrf2-mediated HO-1 activity to prevent ARPE-19 cells from oxidative injury. The results of this study suggest that mangiferin, as an Nrf2 activator, has potent ROS scavenging activity and may have the potential to protect oxidative stress-mediated ocular diseases.

Keywords: Apoptosis; DNA damage; Mangiferin; Nrf2/HO-1; Reactive oxygen species

DOI: https://doi.org/10.4062/biomolther.2023.175