bims-mideyd 2024-07-07 papers

Issue of 2024‒07‒07
four papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Int Ophthalmol. 2024 Jul 04. 44(1): 314

Vitamin D alleviation of oxidative stress in human retinal pigment epithelial cells.

Xiaolong Yang, Xing Qi, Kun Zuo, Yi Huang, Xiyun Bian, Jing Wang, Hao Yu, Qinbei Feng, Xia Lei, Tingli Chen.

BACKGROUND: Oxidative stress-induced retinal pigment epithelium (RPE) cell damage is a major factor in age-related macular degeneration (AMD). Vitamin D3 (VD3) is a powerful antioxidant and it has been suggested to have anti-aging properties and potential for treating AMD. This study aimed to investigate the effect of VD3 on RPE cell oxidative apoptosis of RPE cells in order to provide experimental evidence for the treatment of AMD.METHODS: Human retinal pigment epithelial cell 19 (ARPE-19) cells were divided into four groups: blank group (untreated), model group (incubated in medium with 400 μmol/L H2O2 for 1 h), VD3 group (incubated in medium with 100 μmol/L VD3 for 24 h), and treatment group (incubated in medium with 400 μmol/L H2O2 for 1 h and 100 μmol/L VD3 for 24 h). Cell viability, cell senescence, ROS content, expression levels of vitamin D specific receptors, Akt, Sirt1, NAMPT, and JNK mRNA expression levels, SOD activity, and MDA, GSH, and GPX levels were measured.
RESULTS: We first established an ARPE-19 cell stress model with H2O2. Our control experiment showed that VD3 treatment had no significant effect on ARPE-19 cell viability within 6-48 h. Treating the stressed ARPE-19 cells with VD3 showed mixed results; caspase-3 expression was decreased, Bcl-2 expression was increased, MDA level of ARPE-19 cells was decreased, GSH-PX, GPX and SOD levels were increased, the relative mRNA expression levels of Akt, Sirt1, NAMPT were increased (P < 0.05), and the relative mRNA expression level of JNK was decreased (P < 0.05).
CONCLUSION: VD3 can potentially slow the development of AMD.

Keywords: AMD; Oxidative stress; VD3

DOI: https://doi.org/10.1007/s10792-024-03240-4

Stem Cell Reports. 2024 Jun 18. pii: S2213-6711(24)00155-3. [Epub ahead of print]

Retinal cells derived from patients with DRAM2-dependent CORD21 dystrophy exhibit key lysosomal enzyme deficiency and lysosomal content accumulation.

Biallelic mutations in DRAM2 lead to an autosomal recessive cone-rod dystrophy known as CORD21, which typically presents between the third and sixth decades of life. Although DRAM2 localizes to the lysosomes of photoreceptor and retinal pigment epithelium (RPE) cells, its specific role in retinal degeneration has not been fully elucidated. In this study, we generated and characterized retinal organoids (ROs) and RPE cells from induced pluripotent stem cells (iPSCs) derived from two CORD21 patients. Our investigation revealed that CORD21-ROs and RPE cells exhibit abnormalities in lipid metabolism, defects in autophagic flux, accumulation of aberrant lysosomal content, and reduced lysosomal enzyme activity. We identified potential interactions of DRAM2 with vesicular trafficking proteins, suggesting its involvement in this cellular process. These findings collectively suggest that DRAM2 plays a crucial role in maintaining the integrity of photoreceptors and RPE cells by regulating lysosomal function, autophagy, and potentially vesicular trafficking.

Keywords: CORD21; DRAM2; RPE cells; autophagy; lipd metabolism; lysosomes; retinal organoids; vesicular transport

DOI: https://doi.org/10.1016/j.stemcr.2024.06.002

Diabetes. 2024 Jul 05. pii: db231036. [Epub ahead of print]

Overexpressed Poldip2 incurs retinal fibrosis via the TGFβ1/SMAD3 signaling pathway in diabetic retinopathy.

Zhiyu Ji, Siyu Lin, Siyu Gui, Jie Gao, Fan Cao, Yiming Guan, Qinyu Ni, Keyang Chen, Liming Tao, Zhengxuan Jiang.

Retinal fibrosis is one of the major features of Diabetic retinopathy. Our recent research has shown that Poldip2 can affect early DR through oxidative stress, but whether or not Poldip2 would regulate retinal fibrosis during DR development is still enigmatic. Here, Diabetic Sprague-Dawley (SD) rats were induced with STZ and treated with AAV9-Poldip2shRNA, while human retinal pigment epithelial cells (ARPE-19) were treated with high glucose (HG) or Poldip2 siRNA. We identified that in STZ-induced DR rats and ARPE-19 treated with high glucose, the expression of Poldip2, TGFβ1, P-SMAD3/SMAD3, MMP9, COL-1, FN, and CTGF increased while the expression of Cadherin decreased. However, deleting Poldip2 inhibited the TGF-β1/SMAD3 signaling pathway and attenuated the above protein expression in vivo and in vitro. Mechanistically, we found that Poldip2 promotes the activation of SMAD3, and facilitates its nuclear translocation through interacting with it, and significantly enhances the expression of fibrosis makers. Collectively, it was identified that Poldip2 is a novel regulator of DR fibrosis and it is expected to become a therapeutic target for PDR.

DOI: https://doi.org/10.2337/db23-1036

Invest Ophthalmol Vis Sci. 2024 Jul 01. 65(8): 1

Protective Effect of Nicotinamide Riboside on Glucocorticoid-Induced Glaucoma: Mitigating Mitochondrial Damage and Extracellular Matrix Deposition.

Nan Zhang, Pengyu Zhang, Xizhi Deng, Min Zhu, Yixin Hu, Dongxiao Ji, Lufan Li, Yang Liu, Wen Zeng, Min Ke.

Purpose: Glucocorticoid-induced glaucoma (GIG) is a prevalent complication associated with glucocorticoids (GCs), resulting in irreversible blindness. GIG is characterized by the abnormal deposition of extracellular matrix (ECM) in the trabecular meshwork (TM), elevation of intraocular pressure (IOP), and loss of retinal ganglion cells (RGCs). The objective of this study is to investigate the effects of nicotinamide riboside (NR) on TM in GIG.Methods: Primary human TM cells (pHTMs) and C57BL/6J mice responsive to GCs were utilized to establish in vitro and in vivo GIG models, respectively. The study assessed the expression of ECM-related proteins in TM and the functions of pHTMs to reflect the effects of NR. Mitochondrial morphology and function were also examined in the GIG cell model. GIG progression was monitored through IOP, RGCs, and mitochondrial morphology. Intracellular nicotinamide adenine dinucleotide (NAD+) levels of pHTMs were enzymatically assayed.
Results: NR significantly prevented the expression of ECM-related proteins and alleviated dysfunction in pHTMs after dexamethasone treatment. Importantly, NR protected damaged ATP synthesis, preventing overexpression of mitochondrial reactive oxygen species (ROS), and also protect against decreased mitochondrial membrane potential induced by GCs in vitro. In the GIG mouse model, NR partially prevented the elevation of IOP and the loss of RGCs. Furthermore, NR effectively suppressed the excessive expression of ECM-associated proteins and mitigated mitochondrial damage in vivo.
Conclusions: Based on the results, NR effectively enhances intracellular levels of NAD+, thereby mitigating abnormal ECM deposition and TM dysfunction in GIG by attenuating mitochondrial damage induced by GCs. Thus, NR has promising potential as a therapeutic candidate for GIG treatment.

DOI: https://doi.org/10.1167/iovs.65.8.1