bims-mideyd 2026-01-11 papers

J Ophthalmol. 2025 ;2025 6121757

Caffeine Alleviates Oxidative Damage of Retinal Pigment Epithelium Cells.

Haiyu Liu, Wenwen Zhang, Yucong Xiong, Meiling Yang, Huirong Long, Chaoju Gong, Suyan Li.

Purpose: The purpose of this study was to explore the protective effect of caffeine on oxidative damage of RPE cells and NaIO3-induced retinal degeneration.
Methods: H2O2 was used to induce the oxidative damage in ARPE-19 cells. Cell viability was measured by the CCK-8 assay. The morphology of ARPE-19 cells was observed by optical microscope. The apoptosis of ARPE-19 cells was analyzed by Annexin V/PI staining, and DNA fragmentation was detected using the TUNEL assay. The protein levels of apoptosis markers BAX and BCL2 as well as senescence marker p21 were detected by Western blot. DNA damage was indicated by immunofluorescence staining of γ-H2AX and observed by fluorescence microscopy. Transcriptome profiling of ARPE-19 cells was performed by RNA-seq. In vivo model of retinal oxidative damage was constructed by injecting NaIO3 into the tail vein of C57BL/6 mice. H&E staining was performed after removing the eyeballs.
Results: The CCK-8 assay showed that caffeine could significantly increase the cell viability inhibited by 200 μM H2O2. Caffeine significantly reduced H2O2-induced DNA fragmentation and apoptosis in ARPE-19 cells, as demonstrated by the TUNEL assay and Annexin V/PI staining. The results of Western blot showed that caffeine modulated key proteins associated with apoptosis by decreasing BAX and p21 levels while increasing BCL2 expression in H2O2-treated ARPE-19 cells, thereby suggesting its cytoprotective effects. In terms of mechanism, caffeine reduced the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) produced by H2O2. Caffeine treatment attenuated the accumulation of γ-H2AX, a marker of DNA damage, in ARPE-19 cells. Importantly, transcriptome profiling revealed that caffeine might affect complement cascade and lipid metabolism in H2O2-treated ARPE-19 cells. Finally, in vivo experiment suggested that chronic administration of caffeine could alleviate oxidative damage of the RPE layer and improve the structure of the entire retina in mice with NaIO3-induced retinal degeneration.
Conclusion: Caffeine can reduce oxidative damage of RPE cells and improve NaIO3-induced retinal degeneration.

Keywords: ARPE-19; NaIO3; apoptosis; caffeine; oxidative damage

DOI: https://doi.org/10.1155/joph/6121757

bioRxiv. 2025 Dec 27. pii: 2025.12.27.696636. [Epub ahead of print]

BDH1-Dependent Ketone Body Metabolism Maintains Müller Cell Homeostasis and Retinal Function.

Richa Garg, Eshani Karmakar, David DeBruin, Shauna Prasad, Ethan Naquin, Michelle Brennan, Niloofar Piri, Oleg Kisselev, Jaya P Gnana-Prakasam.

Ketone body metabolism serves as an auxiliary regulator of cellular energetics and redox balance, particularly during prolonged fasting and carbohydrate restriction, yet its role in retinal homeostasis under physiological conditions remains poorly defined. β-hydroxybutyrate dehydrogenase 1 (BDH1) is a mitochondrial enzyme that interconverts acetoacetate and β-hydroxybutyrate, and is required for efficient ketone utilization. Here, we investigated the impact of impaired endogenous ketone metabolism on retinal function using global and retinal pigment epithelium (RPE)-specific BDH1 knockout (KO) mice. Global BDH1 KO mice showed reduced circulating β-hydroxybutyrate and blunted fasting-induced ketone elevations, accompanied by ganglion cell loss, structural abnormalities on fundus and OCT imaging, and diminished scotopic and photopic electroretinogram (ERG) a- and b-wave amplitudes, consistent with impaired photoreceptor responses and downstream bipolar and Müller cell signaling. In contrast, RPE-specific BDH1 KO mice exhibited no changes in ERG responses or retinal morphology. Transcriptomic and molecular analyses in global KO retinas revealed disrupted Müller cell homeostasis, including reduced CAMKII-CREB activation, which is required for EAAT1 glutamate transporter expression. Administration of exogenous β-hydroxybutyrate, in vitro and in vivo, restored CAMKII-CREB-EAAT1 signaling, glutamate uptake, and antioxidant gene expression in BDH1 KO mice, demonstrating a central role for ketone bodies in Müller cell metabolic support, glutamate homeostasis, and redox balance. Together with reduced BDH1 expression in human AMD retinas, these findings identify the BDH1-β-hydroxybutyrate axis as a critical metabolic pathway for Müller cell function and retinal integrity, and highlight ketone metabolism as a potential therapeutic target in degenerative retinal diseases.

Keywords: AMD; CAMKII-CREB; Müller cells; glutamate transporter; neurodegeneration; retinal dysfunction; β-hydroxybutyrate

DOI: https://doi.org/10.64898/2025.12.27.696636

Free Radic Biol Med. 2026 Jan 06. pii: S0891-5849(26)00015-8. [Epub ahead of print]

Mitochondrial Cysteinyl-tRNA Synthetase 2 Protects Against Excitotoxic Retinal Cell Death via Enhanced Supersulfide Production.

Yuri Chida, Risa Shiokawa, Hiroshi Tawarayama, Minami Takeda, Hirokazu Hasegawa, Naoki Takahashi, Hiroshi Kunikata, Takaaki Akaike, Toru Nakazawa.

Mitochondrial cysteinyl-transfer RNA synthetase 2 (CARS2) is involved not only in the ligation of cysteine to transfer RNA but also in the synthesis of intracellular supersulfides. In this study, we investigated the role of CARS2 in the survival of retinal ganglion cells (RGCs) under excitotoxic conditions. Immunohistochemical analysis showed strong expression of CARS2 in RBPMS-positive RGCs in the mouse retina. Overexpression of exogenous human CARS2 (hCARS2) in mouse retinas and in the rat-derived retinal cell line R28 did not affect endogenous CARS2 mRNA levels. Adeno-associated virus 2-mediated overexpression of hCARS2 in RGCs significantly reduced cell death induced by excitotoxicity following intravitreal injection of N-methyl-D-aspartate. Similarly, hCARS2 overexpression decreased glutamate-induced excitotoxic cell death in R28 cells. Quantitative reverse transcription polymerase chain reaction analysis demonstrated a significant increase in CARS2 expression in R28 cells treated with glutamate. Using specific probes, we found that hCARS2-overexpressing R28 cells treated with glutamate exhibited higher intracellular levels of sulfane sulfur species and lower levels of reactive oxygen species (ROS) than control cells with basal CARS2 expression. Moreover, the oxidative stress marker gene Hmox1 was significantly downregulated in CARS2-overexpressing R28 cells compared with control cells. Taken together, these findings suggest that CARS2 plays a critical role in protecting retinal cells from excitotoxic cell death by increasing sulfane sulfur production and decreasing ROS accumulation. Given that CARS2 is predominantly expressed in RGCs among retinal cells, it may serve as a preemptive defense mechanism that enhances antioxidative activity at basal expression levels to support RGC survival.

Keywords: CARS2; RGC degeneration; neuroexcitotoxicity; oxidative stress; supersulfide

DOI: https://doi.org/10.1016/j.freeradbiomed.2026.01.009