Inhibition of ferroptosis promotes retina ganglion cell survival in experimental optic neuropathies

Blue light induced ferroptosis in retinal damage via iron overload-associated oxidative stress

The issue of light pollution has garnered increased attention recently, largely due to the widespread use of electronic devices. Blue light (BL) holds the highest energy level among visible light and has been extensively researched for its potential to cause damage to the retina. Ferroptosis, a recently identified form of programmed cell death form, has been linked to retinal diseases. However, the connection between BL-induced retinal damage and ferroptosis remains elusive. This study aims to investigate the involvement of ferroptosis in retinal damage under BL exposure and its underlying mechanism. In this study, a mouse retinal damage model and cultured ARPE-19 cells exposed to BL were employed. Various techniques including Haematoxylin-eosin staining, fundus photography, immunostaining, and transmission electron microscopy were employed to examine retinal structure and morphology changes resulting from BL exposure. To identify ferroptosis levels in vitro, we employed DCFH-DA, C11-BODIPY 581/591, and FeRhoNox™-1 probes. Additionally, real-time PCR and western blotting techniques were used to uncover potential targets in BL-induced ferroptosis. Our study showed that BL exposure can result in iron overload, oxidative stress, evidenced by increased markers TFR1, ACSL4, HO-1 and decreased expression level of SOD2, CAT and ferroptosis-associated gene of GPX4. Interestingly, we found that Deferoxamine mesylate, a compound capable of chelating excess Fe2+ caused by BL, effectively mitigated lipid peroxidation, and alleviated retinal damage both in vivo and in vitro. The discoveries will advance our knowledge of BL-induced retinal damage.

SETD1B promotes brain cell ferroptosis in ischemic stroke mice via increasing H3K4me3 enrichment on the Tfrc promoter

AIMS

This study investigates the role of SET domain containing 1B (SETD1B), a histone lysine methyltransferase, in promoting ferroptosis induced by ischemic stroke through the upregulation of transferrin receptor 1 (TfR1).

MATERIALS AND METHODS

An ischemic stroke model was established in C57BL/6J mice by subjecting them to 1 h of ischemia followed by 24 h of reperfusion. Brain damage was assessed by neurological impairment and infarct volume. Levels of SETD1B, TfR1, total iron, Fe2+, lipid peroxidation (LPO), ferritin (FPN), and GPX4 were measured. In vitro, HT22 cells were subjected to 14 h of oxygen-glucose deprivation (OGD) followed by 24 h of reoxygenation. SETD1B knockdown was performed to assess its impact on ferroptosis.

KEY FINDINGS

In the ischemic stroke mice, SETD1B expression was elevated, accompanied by increased ferroptosis markers, including higher levels of TfR1, total iron, Fe2+, and LPO, as well as reduced levels of FPN and GPX4. These phenomena were observed in cultured HT22 cells under OGD/R conditions. SETD1B knockdown effectively reversed these effects, decreasing ferroptosis markers and reducing Tfrc expression via preventing H3K4me3 enrichment at the Tfrc promoter.

SIGNIFICANCE

These findings suggest that SETD1B enhances ferroptosis in stroke brain cells by a mechanism involving boosting H3K4me3 enrichment at the Tfrc promoter and subsequent upregulation of the expression of Tfrc. Targeting SETD1B may provide a therapeutic strategy for mitigating ferroptosis in stroke.

Transcription factor KLF5 regulates MsrB1 to promote colorectal cancer progression by inhibiting ferroptosis through β-catenin

Methionine sulfoxide reductase B1 (MsrB1), a member of the selenoprotein family with a catalytic site containing a selenocysteine (Sec) residue, has been identified as an oncogene in colorectal cancer (CRC). However, the regulatory mechanisms of MsrB1 and the relationship between its oncogenic role and antioxidant capacity are not well understood. In this study, we show that either overexpression or suppression of MsrB1 in CRC cells leads to significant phenotypic changes, confirming its role in oncogenesis. To explore the molecular regulatory mechanisms of MsrB1, we used bioinformatic analyses to predict transcription factors within its promoter region, and validated these predictions using dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays. These assays revealed that Krüppel-like factor 5 (KLF5), acting as a transcription factor, binds to the MsrB1 promoter and activates it. Additionally, through Weighted Gene Co-expression Network Analysis (WGCNA) and Co-IP experimental validation, we identified β-catenin, a key component of the Wnt signaling pathway, as being co-expressed with MsrB1. The interaction between MsrB1 and β-catenin leads to the activation of GPX4 transcription, a known ferroptosis marker, which results in the inhibition of ferroptosis and promotion of oncogenesis in CRC. In conclusion, this study elucidates the transcriptional regulatory mechanism of MsrB1 and its role in inhibiting ferroptosis in conjunction with β-catenin. These findings suggest that MsrB1 may be a promising predictive biomarker and therapeutic target for CRC, extending its role beyond that of a conventional antioxidant selenoprotein.

Dimercaprol attenuates oxidative stress-induced damage of retinal ganglion cells in an in vitro and in vivo model of traumatic optic neuropathy

Traumatic optic neuropathy (TON) is a prevalent form of optic neuropathy, which is a significant cause of irreversible blindness. To date, effective therapeutic interventions for TON are lacking, highlighting the urgent need for the development of new therapeutic drugs. In this study, a compound library comprising 480 Food and Drug Administration (FDA)-approved drugs was screened to identify potentially effective therapeutic drugs for TON. We reported that dimercaprol (DMP), an FDA-approved drug, can reduce L-Glutamic acid (Glu) and hydrogen peroxide (H2O2)-induced injury in a retinal cell line (R28 cell). Our findings further demonstrated that intracellular reactive oxygen species (ROS) and acrolein, a lipid peroxide, are major contributors to apoptosis-induced cell death in vitro. A series of functional assays revealed that DMP can inhibit apoptosis-induced by Glu via scavenging of intracellular ROS and acrolein in R28 cells and primary cortical neurones. Notably, DMP inhibited retinal ganglion cell complex (GCC) thinning and retinal ganglion cell (RGC) loss resulting from optic nerve crush (ONC) injury in vivo. Moreover, DMP effectively eliminated ONC-induced acrolein in the retina and inhibited RGC apoptosis in vivo. In conclusion, intracellular ROS and acrolein play significant roles in RGC loss in TON, and DMP effectively inhibits RGC apoptosis-induced by the oxidative stress pathway in vitro and in vivo. Therefore, DMP has emerged as a potential new therapeutic drug against TON.

Mung bean-derived carbon dots suppress ferroptosis of Schwann cells via the Nrf2/HO-1/GPX4 pathway to promote peripheral nerve repair

Schwann cells (SCs) can potentially transform into the repair-related cell phenotype after injury, which can promote nerve repair. Ferroptosis occurs in the SCs of injured tissues, causing damage to the SCs and exacerbating nerve injury. Targeting ferroptosis in SCs is a promising therapeutic strategy for effective repair; however, research on ferroptosis in the peripheral nervous system remains limited. In this study, we generated and characterized novel distinctive carbon dots, mung bean-derived carbon dots (MB-CDs). Our results demonstrated that MB-CDs have the advantages of low toxicity, good biocompatibility, high stability, the specific effect of ferric ions (Fe3+) on fluorescence, and antioxidant activity. We demonstrated that MB-CDs promoted functional recovery after peripheral nerve injury (PNI), preventing gastrocnemius atrophy. Further research indicated that MB-CDs boosted the repair-related phenotypes of SCs. We used lipopolysaccharide (LPS) to induce an inflammatory model of SCs and co-cultured them with MB-CDs. Then, we examined the effects of MB-CDs by dividing the cells into four groups: the control group (CTRL), MB-CD treatment group (CDs-SCs), LPS treatment group (LPS-SCs), and LPS and MB-CD treatment group (LPS-CDs). RNA sequencing of LPS-CDs and LPS-SCs indicated that LPS-CDs significantly upregulated heme oxygenase-1 (HO-1) expression. Furthermore, western blotting and immunofluorescence techniques demonstrated that MB-CDs suppressed the ferroptosis of SCs via the Nrf2/HO-1/GPX4 signaling pathway after PNI. Overall, this study further uncovered the connection between ferroptosis and the repair-related phenotypes of SCs, filling this gap in the existing knowledge; accordingly, they may be promising agents for treating PNI.

Ferroptosis Contributes to Retinal Ganglion Cell Loss in GLAST Knockout Mouse Model of Normal Tension Glaucoma

Purpose

Visual impairment from normal-tension glaucoma (NTG) poses an increasing burden, yet the underlying mechanism remains unclear. Investigating protective mechanisms for NTG is critical. We aimed to investigate the role of ferroptosis in retinal ganglion cell (RGC) damage in glutamate-aspartate transporter (GLAST) knockout (GLAST-/-) mice, a model for NTG, and also to determine whether inhibiting ferroptosis can provide neuroprotection.

Methods

GLAST-/- mice and a glutamate-induced excitotoxicity model in primary RGCs were used to investigate retinal and RGC damage. RNA sequencing identified ferroptosis-related pathways in GLAST-/- retinas. Oxidative stress, lipid peroxidation, and ferroptosis activation were assessed using western blotting and immunofluorescence. Immunohistochemistry (IHC) assessed lipid peroxidation and ferroptosis activation in human retinal tissue. Ferrostatin-1 (Fer-1) was administered to evaluate its neuroprotective effects on RGC survival, retinal thickness, and visual function.

Results

RNA sequencing revealed significant enrichment of ferroptosis-related pathways in GLAST-/- retinas. Both GLAST deletion and glutamate-induced excitotoxicity increased oxidative stress, lipid peroxidation, and ferroptosis activation in RGCs. IHC in human retinas confirmed elevated 4-hydroxynonenal (4-HNE) and acyl-coenzyme A synthetase long-chain family member 4 (ACSL4) expression. Furthermore, Fer-1 treatment significantly reduced lipid peroxidation, thereby attenuating the ferroptosis pathways. This intervention ameliorated RGC loss associated with GLAST deletion, protected retinal structure and thickness, and improved amplitudes of the photopic negative response, a-wave, b-wave, and oscillatory potentials.

Conclusions

Ferroptosis significantly contributes to RGC and retinal damage in the GLAST-deletion NTG model. Inhibiting ferroptosis with Fer-1 presents a promising therapeutic strategy for protecting visual function in NTG.

TF and TFRC regulate ferroptosis in swine testicular cells through the JNK signaling pathway

Transferrin (TF) is a serum glycoprotein that plays a critical role in iron metabolism and typically functions through binding to its transferrin receptor (TFRC). TF is also considered a key indicator of sperm quality and, together with TFRC, plays a critical role in regulating spermatogenesis. This study aimed to explore the effects of increased TF and TFRC expression on ferroptosis in swine testicular cells (ST cells). Our findings revealed that the overexpression of either TF or TFRC diminishes ST cell viability, increases cytotoxicity, intensifies oxidative stress damage, decreases mitochondrial activity, and promotes ferroptosis. Transcriptomic analysis suggested that TF and TFRC may influence ST cells through the MAPK signaling pathway. Subsequent experiments revealed that inhibiting the JNK signaling pathway within the MAPK pathway improved mitochondrial activity, reduced oxidative stress damage, and mitigated ferroptosis progression. Moreover, we discovered that TF and TFRC might regulate cellular oxidative phosphorylation via the JNK signaling pathway. In conclusion, increased expression of TF or TFRC increases the sensitivity of ST cells to ferroptosis and modulates mitochondrial DNA transcription and energy metabolism through the JNK signaling pathway. These findings could offer potential therapeutic targets for addressing reproductive toxicity associated with ferroptosis.

From bench to bedside: targeting ferroptosis and mitochondrial damage in the treatment of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a common and fatal cardiac complication caused by diabetes, with its pathogenesis involving various forms of cell death and mitochondrial dysfunction, particularly ferroptosis and mitochondrial injury. Recent studies have indicated that ferroptosis and mitochondrial damage play crucial roles in the onset and progression of DCM, though their precise regulatory mechanisms remain unclear. Of particular interest is the interaction between ferroptosis and mitochondrial damage, as well as their synergistic effects, which are not fully understood. This review summarizes the roles of ferroptosis and mitochondrial injury in the progression of DCM and explores the molecular mechanisms involved, with an emphasis on the interplay between these two processes. Additionally, the article offers an overview of targeted drugs shown to be effective in cellular experiments, animal models, and clinical trials, analyzing their mechanisms of action and potential side effects. The goal is to provide insights for future drug development and clinical applications. Moreover, the review explores the challenges and prospects of multi-target combination therapies and personalized medicine interventions in clinical practice to offer strategic guidance for the comprehensive prevention and management of DCM.

Iron, lipid peroxidation, and ferroptosis play pathogenic roles in atherosclerosis

Oxidation of lipids, excessive cell death, and iron deposition are prominent features of human atherosclerotic plaques. While extensive research has established the detrimental roles of lipid oxidation and apoptosis in atherosclerosis development, the involvement of iron in atherogenesis is not yet fully understood. With the emergence of an iron-dependent form of cell death termed ferroptosis, new attention has been brought to the complex inter-play among iron, ferroptosis, and atherosclerosis. Mechanistically, ferroptosis is caused by the lethal accumulation of iron-mediated lipid peroxides. Emerging studies have underscored ferroptosis as a contributor to worsened atherosclerosis. Herein, we review the evidence that oxidative damage and iron overload in the context of atherosclerosis may promote ferroptosis within plaques. Furthermore, we summarize recent findings of lipid peroxidation, thereby potentially ferroptosis, in various plaque cell types-such as endothelial cells, macrophages, dendritic cells, T cells, and vascular smooth muscle cells-across different stages of atherosclerosis. Understanding how these processes influence atherosclerotic plaque progression may permit targeting stage-dependent ferroptosis in each cell population and could provide a rationale for developing cell type-specific intervention strategies to mitigate atherogenic ferroptosis effectively.

BMP4-GPX4 can improve the ferroptosis phenotype of retinal ganglion cells and enhance their differentiation ability after retinal stem cell transplantation in glaucoma with high intraocular pressure

Activation of bone morphogenetic protein (BMP) 4 signaling promotes the survival of retinal ganglion cell (RGC) after acute injury. In this study, we investigated the role of the BMP4 signaling pathway in regulating the degeneration of retinal ganglion cells (RGCs) in a mouse glaucoma model and its potential application in retinal stem cell. Our results demonstrate that BMP4-GPX4 not only reduces oxidative stress and iron accumulation but also promotes neuroprotective factors that support the survival of transplanted RSCs into the host retina. These findings suggest a novel therapeutic approach for glaucoma involving the modulation of the BMP4-GPX4 pathway to protect RGCs and improve visual function through enhanced RSC differentiation.

Preserving blood-retinal barrier integrity: a path to retinal ganglion cell protection in glaucoma and traumatic optic neuropathy

Retinal ganglion cells (RGCs) are the visual gateway of the brain, with their axons converging to form the optic nerve, making them the most vulnerable target in diseases such as glaucoma and traumatic optic neuropathy (TON). In both diseases, the disruption of the blood-retinal barrier(BRB) is considered an important mechanism that accelerates RGC degeneration and hinders axon regeneration. The BRB consists of the inner blood-retinal barrier (iBRB) and the outer blood-retinal barrier (oBRB), which are maintained by endothelial cells(ECs), pericytes(PCs), and retinal pigment epithelial (RPE), respectively. Their functions include regulating nutrient exchange, oxidative stress, and the immune microenvironment. However, in glaucoma and TON, the structural and functional integrity of the BRB is severely damaged due to mechanical stress, inflammatory reactions, and metabolic disorders. Emerging evidence highlights that BRB disruption leads to heightened vascular permeability, immune cell infiltration, and sustained chronic inflammation, creating a hostile microenvironment for RGC survival. Furthermore, the dynamic interplay and imbalance among ECs, PCs, and glial cells within the neurovascular unit (NVU) are pivotal drivers of BRB destruction, exacerbating RGC apoptosis and limiting optic nerve regeneration. The intricate molecular and cellular mechanisms underlying these processes underscore the BRB's critical role in glaucoma and TON pathophysiology while offering a compelling foundation for therapeutic strategies targeting BRB repair and stabilization. This review provides crucial insights and lays a robust groundwork for advancing research on neural regeneration and innovative optic nerve protective strategies.

Targeted Neuroprotection of Retinal Ganglion Cells Via AAV2-hSyn-NGF Gene Therapy in Glaucoma Models

Purpose

The purpose of this study was to evaluate the neuroprotective effects of delivering nerve growth factor (NGF) to retinal ganglion cells (RGCs) through adeno-associated virus serotype 2 (AAV2) carrying a neuronal-specific human synapsin (hSyn) promoter.

Methods

AAV2-hSyn-NGF was injected intravitreally in three glaucoma models: optic nerve crush (ONC), microbead-induced ocular hypertension (MB), and genetic glaucoma model (DBA). Quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA) determined the optimal injection concentration of AAV vector. Flow cytometry monitored immune responses. Transduction efficiency was quantified using green fluorescent protein (GFP) co-localization with RGC-specific marker RNA-binding protein with multiple splicing (RBPMS). The RGCs' density, retinal nerve fiber density, ganglion cell complex thickness, and positive scotopic threshold response (pSTR) were measured to assess structural and functional outcomes of the RGCs. Non-parametric Mann-Whitney U tests or Kruskal-Wallis tests were utilized to ascertain the statistical significance (P < 0.05).

Results

The optimal concentration of AAV vector for intravitreal injection was determined to be 1 × 1010 vector particles (VPs) per eye. The use of the hSyn promoter significantly enhanced targeting specificity to RGCs, resulting in a transduction efficiency of 46.64% ± 2.18%. Administration of AAV2-hSyn-NGF effectively preserved the RGCs' density, nerve fiber layer integrity, and the thickness of ganglion cell complex, while maintaining the RGCs' function across three glaucoma models. Furthermore, this gene delivery system did not elicit detectable immune responses or structural damage to the retina.

Conclusions

The AAV2-hSyn-NGF gene therapy offers a safe and effective neuroprotective strategy for RGCs across multiple glaucoma models, making it a promising candidate for future clinical trials in patients with glaucoma.

Vitamin K1 Alleviates Retinal Inflammation Following Acute Ocular Hypertension by Modulating Microglial Ferroptosis

Purpose

Glaucoma is the leading cause of irreversible blindness worldwide and encompasses a group of diseases characterized by optic nerve atrophy and visual field defects. Acute intraocular pressure (IOP) elevation is a key driver of retinal inflammation and optic nerve damage, often accompanied by microglial activation and dysregulated ferroptosis pathways. Vitamin K1, a fat-soluble vitamin, possesses anti-inflammatory and antioxidant properties, and has the potential to regulate ferroptosis. However, its mechanisms in alleviating retinal inflammation following acute IOP elevation remain unclear.

Methods

In vivo, we established a mouse model of acute ocular hypertension to evaluate the protective effects of vitamin K1 on the retina and visual function. Transcriptome sequencing was used to explore the underlying mechanisms by which vitamin K1 exerts its effects. Immunofluorescence and Western blot were used to assess retinal inflammation and observe ferroptosis in microglia. In vitro, we developed a BV2 cell OGDR model to investigate the regulatory effects of vitamin K1 on iron metabolism and inflammation in microglia.

Results

Our findings demonstrated that acute IOP elevation led to microglial activation, along with iron overload and ferroptosis in microglia. Further analyses revealed that microglial ferroptosis was accompanied by an upregulation of inflammatory cytokine gene expression and protein levels. Vitamin K1 intervention, however, inhibited microglial ferroptosis, alleviated retinal inflammation, minimized retinal ganglion cell (RGC) loss, and protected visual function.

Conclusions

In conclusion, this study demonstrates that vitamin K1 exerts a protective effect by modulating microglial ferroptosis, thereby alleviating acute ocular hypertension-induced retinal inflammation.

Paeonol ameliorates ferroptosis and inflammation in chondrocytes through AMPK/Nrf2/GPX4 pathway

Introduction

Chondrocyte ferroptosis is an important component of the pathogenesis of osteoarthritis. Paeonol, the main pharmacologically active ingredient of the Paeonia suffruticosa Andrews, is a natural radical scavenger with potent biological activities, including antioxidant, anti-inflammatory, and cartilage protection effects. However, the molecular mechanisms underlying its role in regulating chondrocytes ferroptosis remain unclear.

Methods

To investigate the effect of paeonol on ferroptosis and inflammation of chondrocytes through interleukin-1β (IL-1β), the proliferation activity, lipid peroxidation level, endogenous antioxidant capacity, and mitochondrial membrane potential of chondrocytes were evaluated in detail. Intracellular ferrous ion concentration was detected by FerroOrange fluorescent probe staining. Western blotting and immunofluorescence staining were used to detect biomarker proteins of ferroptosis, inflammation, and AMPK/Nrf2/GPX4 signaling pathway proteins.

Results

The results showed that paeonol significantly depressed IL-1β-induced ferroptosis and inflammation in chondrocytes. Specifically, paeonol protects cell viability, reduces lipid peroxidation damage, maintains mitochondrial function, and inhibits pro-ferroptosis and pro-inflammation biomarker proteins. In addition, the anti-inflammatory ability of paeonol was partially inhibited after the addition of ferroptosis agonist erastin, suggesting that paeonol protects against inflammatory injury in part by inhibiting ferroptosis. Further studies showed that paeonol activated AMPK phosphorylation and promoted Nrf2 nuclear translocation and Keap1 degradation. Finally, the AMPK-Nrf2-GPX4 signaling pathway was confirmed to be the underlying mechanism of paeonol against ferroptosis by the simultaneous use of the AMPK agonist and Nrf2 inhibitor.

Conclusion

These results indicate that paeonol significantly inhibits IL-1β-induced ferroptosis and inflammation in chondrocytes, and the underlying mechanism of paeonol against ferroptosis is partly through the AMPK/Nrf2/GPX4 axis.

Inhibition of Phosphodiesterase 4 Suppresses Neuronal Ferroptosis After Cerebral Ischemia/Reperfusion

We have previously shown that inhibition of phosphodiesterase 4 (PDE4) protects against cerebral ischemia/reperfusion injury. However, it remains unclear whether and how PDE4 affects ferroptosis under cerebral ischemia/reperfusion conditions. In this study, we found that overexpression of PDE4B in HT-22 cells exacerbated the detrimental effects of oxygen-glucose deprivation/reoxygenation (OGD/R), including a decrease in cell viability and glutathione (GSH) levels and an increase in Fe2+ content. PDE4B knockdown mitigated the effects of OGD/R, as evidenced by decreased oxidative stress, lactate dehydrogenase (LDH) release, Fe2+ content, and nuclear receptor coactivator 4 (NCOA4) expression. PDE4B knockdown also enhanced the levels of GSH, ferroportin (FPN), and ferritin heavy chain 1 (FTH1). Consistently, inhibition of PDE4 by roflumilast (Roflu) produced similar effects as PDE4B knockdown. Roflu also ameliorated the morphology and membrane potential of the mitochondria. Glutathione peroxidase 4 (GPX4) knockdown blocked the effects of Roflu on cell viability and lipid peroxidation. Moreover, we found that nuclear factor erythroid 2-related factor 2 (Nrf-2) knockdown decreased GPX4 expression. In addition, Nrf-2 knockdown led to enhanced lipid peroxidation, LDH release, and iron levels, while the GSH and FPN levels decreased. More crucially, PDE4 inhibition decreased infarct volume, alleviated oxidative stress, and restored the expression levels of ferroptosis-associated proteins in middle cerebral artery occlusion/reperfusion (MCAO/R) rats. Interestingly, the GPX4 inhibitor RSL3 blocked the neuroprotective effects of Roflu in rats subjected to MCAO/R. Thus, PDE4 inhibition significantly inhibits neuronal ferroptosis by activating the Nrf-2/GPX4 pathway. These data indicate the existence of a novel mechanism underlying the neuroprotective effects of PDE4 inhibition.

FABP3 promotes cell apoptosis and oxidative stress by regulating ferroptosis in lens epithelial cells

The purpose of this study is to investigate FABP3's biological function and potential mechanism in cataract. Treatment of H2O2 raised FABP3 expression. H2O2 decreased cell viability, enhanced apoptosis, promoted Bax and cleaved caspase-3 expression, inhibited Bcl-2 expression, enhanced the levels of IL-6, IL-1β, and TNF-α, raised MDA level, and decreased SOD and GSH levels in HLE-B3 cells. However, the effects of H2O2 on cell viability, apoptosis, inflammatory cytokines, and oxidative stress were reversed by FABP3 knockdown and aggravated by FABP3 overexpression. H2O2 increased the levels of lipid hydroperoxides and Fe2+, but reduced the expression of GPX4, SLC7A11, and Ferritin protein. Nevertheless, knockdown of FABP3 reversed the changes of lipid hydroperoxides, Fe2+, GPX4, SLC7A11, and Ferritin protein, and FABP3 overexpression caused the opposite results. In addition, the inhibition of FABP3 knockdown on cell apoptosis, inflammation, and oxidative stress was reversed by ferroptosis inducer (erastin), and the promotion of FABP3 overexpression on cell apoptosis, inflammation, and oxidative stress was reversed by ferroptosis inhibitor (Fer-1). Taken together, knockdown of FABP3 in lens epithelial cells treated with H2O2 restrained apoptosis, inflammation, and oxidative stress through regulating ferroptosis, suggesting that FABP3 might be a potential target for cataract treatment.

Activation of PAR1 contributes to ferroptosis of Schwann cells and inhibits regeneration of myelin sheath after sciatic nerve crush injury in rats via Hippo-YAP/ACSL4 pathway

OBJECTIVE

Peripheral nerve injury (PNI) is characterized by high incidence and sequela rate. Recently, there was increasing evidence that has shown ferroptosis may impede functional recovery. Our objective is to explore the novel mechanism that regulates ferroptosis after PNI.

METHODS

LC-MS/MS proteomics was used to explore the possible differential signals, while PCR array was performed to investigate the differential factors. Besides, we also tried to activate or inhibit the key factors and then observe the level of ferroptosis. Regeneration of myelin sheath was finally examined in vivo via transmission electron microscopy.

RESULTS

Proteomics analysis suggested coagulation signal was activated after sciatic nerve crush injury, in which high expression of F2 (encoding thrombin) and F2r (encoding PAR1) were observed. Both thrombin and PAR1-targeted activator TRAP6 can induce ferroptosis in RSC96 cells, which can be rescued by Vorapaxar (PAR1 targeted inhibitor) in vitro. Further PCR array revealed that activation of PAR1 induced ferroptosis in RSC96 cells by increasing expression of YAP and ACSL4. Immunofluorescence of sciatic nerve confirmed that the expression of YAP and ACSL4 were simultaneously reduced after PAR1 inhibition, which may contribute to myelin regeneration after injury in SD rats.

CONCLUSION

Inhibition of PAR1 can relieve ferroptosis after sciatic nerve crush injury in SD rats through Hippo-YAP/ACSL4 pathway, thereby regulating myelin regeneration after injury. In summary, PAR1/Hippo-YAP/ACSL4 pathway may be a promising therapeutic target for promoting functional recovery post-sciatic crush injury.

Identification of Ferroptosis-Associated Genes in Primary Open-Angle Glaucoma through Bioinformatics Analysis

This study aims to examine ferroptosis-associated genes in primary open-angle glaucoma (POAG) and offer new insights into the underlying disease mechanisms and potential therapeutic approaches. Differentially expressed genes (DEGs) between the POAG and control groups were identified using bioinformatics analysis and subsequently intersected with a ferroptosis gene set to isolate ferroptosis-related DEGs (Ferr DEGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted to examine their biological functions. Core genes were identified through protein-protein interaction (PPI) network and Friends analysis. The diagnostic potential of core Ferr DEGs was assessed using receiver operating characteristic (ROC) curve analysis, while immune cell infiltration was examined using the CIBERSORT algorithm. Additionally, Spearman correlation analysis was used to examine the relationships between the identified genes and immune cell populations. A total of 25 Ferr DEGs were identified, with DDIT4, GDF15, NAMPT, HBA1, and IGFBP7 recognized as key core genes. ROC analysis demonstrated that these genes exhibited high diagnostic accuracy, with an AUC > 0.7. Additionally, the infiltration levels of memory B cells and macrophage_M2 were significantly elevated in POAG tissues compared to the control group. Notably, the core genes revealed significant correlations with various immune cell types. Our findings underscore the involvement of ferroptosis-related genes in POAG pathogenesis and highlight their potential as diagnostic biomarkers and therapeutic targets. Future research should focus on validating these findings in clinical settings and exploring the therapeutic modulation of ferroptosis in POAG management.

TMCO1 promotes ferroptosis and ECM deposition in glaucomatous trabecular meshwork via ERK1/2 signaling

Glaucoma, a leading cause of global blindness, is marked by irreversible retinal ganglion cells (RGCs) loss, elevated intraocular pressure (IOP), and extracellular matrix (ECM) deposition in the trabecular meshwork (TM). Transmembrane and coiled-coil domain protein 1 (TMCO1), implicated in calcium regulation, has potential links to primary open-angle glaucoma (POAG). Ferroptosis, an iron-dependent cell death mechanism driven by lipid peroxidation, is also observed in glaucoma. This study investigates the role of TMCO1 in POAG, focusing on its involvement in TM ECM deposition via ferroptosis induction and ERK1/2 phosphorylation inhibition. In both in vivo and in vitro models, we demonstrated that dexamethasone (DEX) stimulation upregulates TMCO1, leading to increased ECM deposition and ferroptosis in human trabecular meshwork cells (HTMCs). Furthermore, treatment with ferrostatin-1 (Fer-1), a ferroptosis inhibitor, significantly reduced ECM deposition and ferroptosis in HTMCs. These findings establish TMCO1 as a critical regulator of ferroptosis and ECM deposition through the ERK/MAPK pathway, positioning it as a promising therapeutic target for glaucoma.

Ion channel Piezo1 induces ferroptosis of trabecular meshwork cells: a novel observation in the pathogenesis in primary open angle glaucoma

This study aims to elucidate the role of Piezo1, a mechanosensitive molecule, in trabecular meshwork cells (TMCs) in the context of primary open angle glaucoma (POAG), a leading cause of irreversible visual impairment. Dysfunction of the trabecular meshwork (TM) is a key factor in the elevated intraocular pressure (IOP) observed in POAG, yet the specific mechanisms leading to TM dysfunction are not fully understood. We performed cell stretching on human trabecular meshwork cells (HTMCs) and pharmacologically activated HTMCs with Yoda1 to study the role of Piezo1 in HTMCs. We focused on assessing cell viability, mitochondrial changes, lipid peroxidation, and the expression of ferroptosis-related targets such as acyl-CoA synthetase long-chain family member 4 (ACSL4) and glutathione peroxidase 4 (GPX4). Cell stretching induces ferroptosis in HTMCs, and this phenomenon is reversed by Piezo1 knockdown. In addition, pharmacological activation of Piezo1 also leads to ferroptosis in HTMCs. Furthermore, inhibiting the JNK/p38 signaling pathway was found to mitigate the ferroptotic response induced by Yoda1, thereby confirming that Piezo1 induces ferroptosis in TMCs through this pathway. Notably, our experiments suggest that Yoda1 may trigger ferroptosis in the TM of mouse eyes. Our findings demonstrate that the Piezo1 pathway is a crucial mediator of ferroptosis in TMCs, providing new insights into the pathogenic mechanisms of glaucoma, particularly POAG. This study highlights the potential of targeting the Piezo1 pathway as a therapeutic approach for mitigating TM dysfunction and managing POAG.NEW & NOTEWORTHY This study is the first to show that cell stretching induces ferroptosis in trabecular meshwork cells (TMCs), dependent on Piezo1 activation. Targeting the Piezo1 pathway offers new therapeutic potential for mitigating trabecular meshwork dysfunction and managing primary open angle glaucoma (POAG). The study also reveals Piezo1 induces ferroptosis via the JNK/p38 signaling pathway.

NIR-Actuated Ferroptosis Nanomotor for Enhanced Tumor Penetration and Therapy

Ferroptosis nano-inducers have drawn considerable attention in the treatment of malignant tumors. However, low intratumoral hydrogen peroxide level and complex biological barriers hinder the ability of nanomedicines to generate sufficient reactive oxygen species (ROS) and achieve tumor penetration. Here a near-infrared (NIR)-driven ROS self-supplying nanomotor is successfully designed for synergistic tumor chemodynamic therapy (CDT) and photothermal therapy (PTT). Janus nanomotor is created by the asymmetrical modification of polydopamine (PDA) with zinc peroxide (ZnO2) and subsequent ferrous ion (Fe2+) chelation via the polyphenol groups from the PDA, here refer as ZnO2@PDA-Fe (Z@P-F). ZnO2 is capable of slowly releasing hydrogen peroxide (H2O2) into an acidic tumor microenvironment (TME) providing sufficient ingredients for the Fenton reaction necessary for ferroptosis. Upon NIR laser irradiation, the loaded Fe2+ is released and a thermal gradient is simultaneously formed owing to the asymmetric PDA coating, thus endowing the nanomotor with self-thermophoresis based enhanced diffusion for subsequent lysosomal escape and tumor penetration. Therefore, the release of ferrous ions (Fe2+), self-supplied H2O2, and self-thermophoresis of nanomotors with NIR actuation further improve the synergistic CDT/PTT efficacy, showing great potential for active tumor therapy.

Self-Assembly Hypoxic and ROS Dual Response Nano Prodrug as a New Therapeutic Approach for Glaucoma Treatments

Glaucoma is an irreversible blinding eye disease characterized by retinal ganglion cell (RGC) death.Previous studies have demonstrated that protecting mitochondria and activating the CaMKII/CREB signaling pathway can effectively protect RGC and axon. However, currently treatments are often unsatisfactory, and the pathogenesis of glaucoma requires further elucidation. In this study, a ROS-responsive dual drug conjugate (OLN monomer) is first designed that simultaneously bonds nicotinamide and oleic acid. The conjugate self-assembled into nanoparticles (uhOLN-NPs) through the aggregation of multiple micelles and possesses ROS scavenging capability. Then, a polymer with a hypoxic response function is designed, which encapsulates uhOLN-NPs to form nanoparticles with hypoxic and ROS responses (HOLN-NPs). Under hypoxia in RGCs, the azo bond of HOLN-NPs breaks and releases uhOLN-NPs. Meanwhile, under high ROS conditions, the thioketone bond broke, leading to the dissociation of nano-prodrug. The released nicotinamide and oleic acid co-scavenge ROS and activate the CaMKII/CREB pathway, protecting mitochondria in RGCs. HOLN-NPs exhibit a significantly superior protective effect on R28 cells in glutamate models of glaucoma. The accumulation of HOLN-NPs in retinal RGCs lead to significant inhibition of RGC apoptosis and axonal damage in vivo. Notably, HOLN-NPs provide a new therapeutic approach for patients with neurodegenerative disease.

Downregulation of LOX Overexpression Promotes Retinal Ganglion Cells Survival in an Acute Ocular Hypertension Model

PURPOSE

To investigate the effect of reducing Lysyl oxidase (LOX) overexpression on retinal ganglion cells (RGCs) apoptosis in an acute ocular hypertension (AOH) rat model.

METHODS

AOH rat model was performed by anterior chamber perfusion and either received an intravitreal injection with β-aminopropionitrile (BAPN) or normal saline. After 2wk, Quantification of survival RGCs in the retina was performed using Retrograde FluoroGold labeling. The mRNA expression levels of LOX, LOXL1-4, collagen 1a1 (Col1a1), collagen 3a1 (Col3a1), collagen4a1 (Col4a1), elastin (Eln), fibronectin1 (Fbn1), fibronectin4 (Fbn4) were determined by RT-qPCR. LOX expression was determined by Western blot (WB) analysis and immunohistochemistry. The RNA expression of LOX, Eln and Col1a1 in RGCs retrograde-labeled with 1,1'-dioctadecyl-3,3,3',3' tetra-methylindocarbocyanine perchlorate(DiI)that selected through FACS sorting were determined by RT-qPCR analysis. Changes of the retinal function were detected by Electroretinogram (ERG) analysis.

RESULTS

Results showed that significant LOX overexpression and loss of RGCs related to IOP exposure in AOH retinas. PCR analysis indicated significant increased mRNA level of Col1a1, Col3al and Eln in AOH retinas. Significant increase mRNA expression of LOX, Col1a1 and Eln in the RGCs were observed in AOH group compared with CON group. AOH rats injected with BAPN showed a significant decrease in LOX expression, reduced the loss of RGCs and retinal function damage.

CONCLUSIONS

The results demonstrated that changes of LOX and specific ECM components in retina were correlated with AOH. Findings from this study indicated that preventing LOX over-expression may be protective against RGCs loss and retinal function damage in AOH animal model.

Targeting ferroptosis: a novel therapeutic strategy for the treatment of retinal diseases

Ferroptosis plays a vital role in the progression of various retinal diseases. The analysis of the mechanism of retinal cell ferroptosis has brought new targeted strategies for treating retinal vascular diseases, retinal degeneration and retinal nerve diseases, and is also a major scientific issue in the field of ferroptosis. In this review, we summarized results from currently available in vivo and in vitro studies of multiple eye disease models, clarified the pathological role and molecular mechanism of ferroptosis in retinal diseases, summed up the existing pharmacological agents targeting ferroptosis in retinal diseases as well as highlighting where future research efforts should be directed for the application of ferroptosis targeting agents. This review indicates that ferroptosis of retinal cells is involved in the progression of age-related/inherited macular degeneration, blue light-induced retinal degeneration, glaucoma, diabetic retinopathy, and retinal damage caused by retinal ischemia-reperfusion via multiple molecular mechanisms. Nearly 20 agents or extracts, including iron chelators and transporters, antioxidants, pharmacodynamic elements from traditional Chinese medicine, ferroptosis-related protein inhibitors, and neuroprotective agents, have a remissioning effect on retinal disease in animal models via ferroptosis inhibition. However, just a limited number of agents have received approval or are undergoing clinical trials for conditions such as iron overload-related diseases. The application of most ferroptosis-targeting agents in retinal diseases is still in the preclinical stage, and there are no clinical trials yet. Future research should focus on the development of more potent ferroptosis inhibitors, improved drug properties, and ideally clinical testing related to retinal diseases.

Unveiling ferroptosis: a new frontier in skin disease research

Ferroptosis, a form of regulated cell death distinct from apoptosis, necrosis, and autophagy, is increasingly recognized for its role in skin disease pathology. Characterized by iron accumulation and lipid peroxidation, ferroptosis has been implicated in the progression of various skin conditions, including psoriasis, photosensitive dermatitis, and melanoma. This review provides an in-depth analysis of the molecular mechanisms underlying ferroptosis and compares its cellular effects with other forms of cell death in the context of skin health and disease. We systematically examine the role of ferroptosis in five specific skin diseases, including ichthyosis, psoriasis, polymorphous light eruption (PMLE), vitiligo, and melanoma, detailing its influence on disease pathogenesis and progression. Moreover, we explore the current clinical landscape of ferroptosis-targeted therapies, discussing their potential in managing and treating skin diseases. Our aim is to shed light on the therapeutic potential of modulating ferroptosis in skin disease research and practice.

Investigating the mechanism of tricyclic decyl benzoxazole -induced apoptosis in liver Cancer cells through p300-mediated FOXO3 activation

OBJECTIVE

To investigate whether tricyclic decylbenzoxazole (TDB) regulates liver cancer cell proliferation and apoptosis through p300-mediated FOXO acetylation.

METHODS

Sequencing, adenovirus, and lentivirus transfection were performed in human liver cancer cell line SMMC-7721 and apoptosis was detected by Tunel, Hoechst, and flow cytometry. TEM for mitochondrial morphology, MTT for cell proliferation ability, Western blot, and PCR were used to detect protein levels and mRNA changes.

RESULTS

Sequencing analysis and cell experiments confirmed that TDB can promote the up-regulation of FOXO3 expression. TDB induced FOXO3 up-regulation in a dose-dependent manner, promoted the expression of p300 and Bim, and enhanced the acetylation and dephosphorylation of FOXO3, thus promoting apoptosis. p300 promotes apoptosis of cancer cells through Bim and other proteins, while HAT enhances the phosphorylation of FOXO3 and inhibits apoptosis. Overexpression of FOXO3 can increase the expression of exo-apoptotic pathways (FasL, TRAIL), endo-apoptotic pathways (Bim), and acetylation at the protein level and inhibit cell proliferation and apoptotic ability, while FOXO3 silencing or p300 mutation can partially reverse apoptosis. In tumor tissues with overexpression of FOXO3, TDB intervention can further increase the expression of p53 and caspase-9 proteins in tumor cells, resulting in loss of mitochondrial membrane integrity during apoptosis, the release of cytoplasm during signal transduction, activation of caspase-9 and synergistic inhibition of growth.

CONCLUSION

TDB induces proliferation inhibition and promotes apoptosis of SMMC-7721 cells by activating p300-mediated FOXO3 acetylation.

NLRP3 and autophagy in retinal ganglion cell inflammation in age-related macular degeneration: potential therapeutic implications

Retinal degenerative diseases were a large group of diseases characterized by the primary death of retinal ganglion cells (RGCs). Recent studies had shown an interaction between autophagy and nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasomes, which may affect RGCs in retinal degenerative diseases. The NLRP3 inflammasome was a protein complex that, upon activation, produces caspase-1, mediating the apoptosis of retinal cells and promoting the occurrence and development of retinal degenerative diseases. Upregulated autophagy could inhibit NLRP3 inflammasome activation, while inhibited autophagy can promote NLRP3 inflammasome activation, which leaded to the accelerated emergence of drusen and lipofuscin deposition under the neurosensory retina. The activated NLRP3 inflammasome could further inhibit autophagy, thus forming a vicious cycle that accelerated the damage and death of RGCs. This review discussed the relationship between NLRP3 inflammasome and autophagy and its effects on RGCs in age-related macular degeneration, providing a new perspective and direction for the treatment of retinal diseases.

Mitochondria in Retinal Ganglion Cells: Unraveling the Metabolic Nexus and Oxidative Stress

This review explored the role of mitochondria in retinal ganglion cells (RGCs), which are essential for visual processing. Mitochondrial dysfunction is a key factor in the pathogenesis of various vision-related disorders, including glaucoma, hereditary optic neuropathy, and age-related macular degeneration. This review highlighted the critical role of mitochondria in RGCs, which provide metabolic support, regulate cellular health, and respond to cellular stress while also producing reactive oxygen species (ROS) that can damage cellular components. Maintaining mitochondrial function is essential for meeting RGCs' high metabolic demands and ensuring redox homeostasis, which is crucial for their proper function and visual health. Oxidative stress, exacerbated by factors like elevated intraocular pressure and environmental factors, contributes to diseases such as glaucoma and age-related vision loss by triggering cellular damage pathways. Strategies targeting mitochondrial function or bolstering antioxidant defenses include mitochondrial-based therapies, gene therapies, and mitochondrial transplantation. These advances can offer potential strategies for addressing mitochondrial dysfunction in the retina, with implications that extend beyond ocular diseases.

Uncovering the role of ferroptosis in Bietti crystalline dystrophy and potential therapeutic strategies

PURPOSE

Bietti crystalline dystrophy (BCD) is an inherited retinal degeneration disease caused by mutations in the CYP4V2 gene. Currently, there is no clinical therapy approach available for BCD patients. Previous research has suggested that polyunsaturated fatty acids (PUFAs) may play a significant role in the development of BCD, implicating the involvement of ferroptosis in disease pathogenesis. In this work, we aimed to investigate the interplay between ferroptosis and BCD and to detect potential therapeutic strategies for the disease.

METHODS

Genetic-edited RPE cell line was first established in this study by CRISPR-Cas9 technology. Cyp4v3 (the homologous gene of human CYP4V2) knock out (KO) mice have also been used. Lipid profiling and transcriptome analysis of retinal pigment epithelium (RPE) cells from Cyp4v3 KO mice have been conducted. Ferroptosis phenotypes have been first investigated in BCD models in vitro and in vivo, including lipid peroxidation, mitochondrial changes, elevated levels of reactive oxygen species (ROS), and altered gene expression. Additionally, an iron chelator, deferiprone (DFP), has been tested in vitro and in vivo to determine its efficacy in suppressing ferroptosis and restoring the BCD phenotype.

RESULTS

Cyp4v3 KO mice exhibited progressive retinal degeneration and lipid accumulation, similar to the BCD phenotype, which was exacerbated by a high-fat diet (HFD). Increased levels of PUFAs, such as EPA (C22:5) and AA (C20:4), were observed in the RPE of Cyp4v3 KO mice. Transcriptome analysis of RPE in Cyp4v3 KO mice revealed changes in genes involved in iron homeostasis, particularly an upregulation of NCOA4, which was confirmed by immunofluorescence. Ferroptosis-related characteristics, including mitochondrial defects, lipid peroxidation, ROS accumulation, and upregulation of related genes, were detected in the RPE both in vitro and in vivo. Abnormal accumulation of ferrous iron was also detected. DFP, an iron chelator administration suppressed ferroptosis phenotype in CYP4V2 mutated RPE. Oral administration of DFP also restored the retinal function and morphology in Cyp4v3 KO mice.

CONCLUSION

This study represented the first evidence of the substantial role of ferroptosis in the development of BCD. PUFAs resulting from CYP4V2 mutation may serve as substrates for ferroptosis, potentially working in conjunction with NCOA4-regulated iron accumulation, ultimately leading to RPE degeneration. DFP administration, which chelates iron, has demonstrated its ability to reverse BCD phenotype both in vitro and in vivo, suggesting a promising therapeutic approach in the future.

Ferroptosis: a novel mechanism of cell death in ophthalmic conditions

Ferroptosis, a new type of programmed cell death proposed in recent years, is characterized mainly by reactive oxygen species and iron-mediated lipid peroxidation and differs from programmed cell death, such as apoptosis, necrosis, and autophagy. Ferroptosis is associated with a variety of physiological and pathophysiological processes. Recent studies have shown that ferroptosis can aggravate or reduce the occurrence and development of diseases by targeting metabolic pathways and signaling pathways in tumors, ischemic organ damage, and other degenerative diseases related to lipid peroxidation. Increasing evidence suggests that ferroptosis is closely linked to the onset and progression of various ophthalmic conditions, including corneal injury, glaucoma, age-related macular degeneration, diabetic retinopathy, retinal detachment, and retinoblastoma. Our review of the current research on ferroptosis in ophthalmic diseases reveals significant advancements in our understanding of the pathogenesis, aetiology, and treatment of these conditions.

FTO deficiency in older livers exacerbates ferroptosis during ischaemia/reperfusion injury by upregulating ACSL4 and TFRC

Older livers are more prone to hepatic ischaemia/reperfusion injury (HIRI), which severely limits their utilization in liver transplantation. The potential mechanism remains unclear. Here, we demonstrate older livers exhibit increased ferroptosis during HIRI. Inhibiting ferroptosis significantly attenuates older HIRI phenotypes. Mass spectrometry reveals that fat mass and obesity-associated gene (FTO) expression is downregulated in older livers, especially during HIRI. Overexpressing FTO improves older HIRI phenotypes by inhibiting ferroptosis. Mechanistically, acyl-CoA synthetase long chain family 4 (ACSL4) and transferrin receptor protein 1 (TFRC), two key positive contributors to ferroptosis, are FTO targets. For ameliorative effect, FTO requires the inhibition of Acsl4 and Tfrc mRNA stability in a m6A-dependent manner. Furthermore, we demonstrate nicotinamide mononucleotide can upregulate FTO demethylase activity, suppressing ferroptosis and decreasing older HIRI. Collectively, these findings reveal an FTO-ACSL4/TFRC regulatory pathway that contributes to the pathogenesis of older HIRI, providing insight into the clinical translation of strategies related to the demethylase activity of FTO to improve graft function after older donor liver transplantation.

Blue light induced ferroptosis via STAT3/GPX4/SLC7A11/FTH1 in conjunctiva epithelium in vivo and in vitro

The prevalence of Light-emitting diodes (LEDs) has exposed us to an excessive amount of blue light (BL) which causes various ophthalmic diseases. Previous studies have shown that conjunctiva is vulnerable to BL. In this study, we aimed to investigate the underlying mechanism of BL-induced injury in conjunctiva. We placed C57BL/6 mice and human conjunctival epithelial cell lines (HCECs) under BL (440 nm ± 15 nm, 0.2 mW/cm2) to establish a BL injury model in vivo and in vitro. Immunohistochemistry and MDA assay were used to identify lipid peroxidation (LPO) in vivo. HE staining was applied to detect morphological damage of conjunctival epithelium. DCFH-DA, C11-BODIPY 581/591, Calcein-AM, and FeRhoNox™-1 probes were performed to identify ferroptosis levels in vitro. Real-time qPCR and Western blotting techniques were employed to uncover signaling pathways of blue light-induced ferroptosis. Our findings demonstrated that BL affected tear film instability and induced conjunctival epithelium injury in vivo. Ferrostatin-1 significantly alleviated blue light-induced ferroptosis in vivo and in vitro. BL downregulates the levels of solute carrier family 7 member 11 (SLC7A11), Ferritin heavy chain (FTH1), and glutathione peroxidase (GPX4) by inhibiting the activation and translocation of the Signal transducer and activator of transcription 3 (STAT3) from inducing Fe2+ burst, ROS and LPO accumulation, ultimately resulting in ferroptosis. This study will offer new insight into BL-induced conjunctival injury and LED-induced dry eye.

The positive feedback loop of the NAT10/Mybbp1a/p53 axis promotes cardiomyocyte ferroptosis to exacerbate cardiac I/R injury

Ferroptosis is a nonapoptotic form of regulated cell death that has been reported to play a central role in cardiac ischemia‒reperfusion (I/R) injury. N-acetyltransferase 10 (NAT10) contributes to cardiomyocyte apoptosis by functioning as an RNA ac4c acetyltransferase, but its role in cardiomyocyte ferroptosis during I/R injury has not been determined. This study aimed to elucidate the role of NAT10 in cardiac ferroptosis as well as the underlying mechanism. The mRNA and protein levels of NAT10 were increased in mouse hearts after I/R and in cardiomyocytes that were exposed to hypoxia/reoxygenation. P53 acted as an endogenous activator of NAT10 during I/R in a transcription-dependent manner. Cardiac overexpression of NAT10 caused cardiomyocyte ferroptosis to exacerbate I/R injury, while cardiomyocyte-specific knockout of NAT10 or pharmacological inhibition of NAT10 with Remodelin had the opposite effects. The inhibition of cardiomyocyte ferroptosis by Fer-1 exerted superior cardioprotective effects against the NAT10-induced exacerbation of post-I/R cardiac damage than the inhibition of apoptosis by emricasan. Mechanistically, NAT10 induced the ac4C modification of Mybbp1a, increasing its stability, which in turn activated p53 and subsequently repressed the transcription of the anti-ferroptotic gene SLC7A11. Moreover, knockdown of Mybbp1a partially abolished the detrimental effects of NAT10 overexpression on cardiomyocyte ferroptosis and cardiac I/R injury. Collectively, our study revealed that p53 and NAT10 interdependently cooperate to form a positive feedback loop that promotes cardiomyocyte ferroptosis to exacerbate cardiac I/R injury, suggesting that targeting the NAT10/Mybbp1a/p53 axis may be a novel approach for treating cardiac I/R.

NADPH and NAC synergistically inhibits chronic ocular hypertension-induced neurodegeneration and neuroinflammation through regulating p38/MAPK pathway and peroxidation

Glaucoma, the leading cause of irreversible blindness worldwide, is characterized by neurodegeneration and neuroinflammation with retinal NAD/NADP and GSH decline. Nicotinamide adenine dinucleotide (NAD)/NAD phosphate (NADP) and glutathione (GSH) are two redox reducers in neuronal and glial metabolism. However, therapeutic strategies targeting NAD/NADP or GSH do not exert ideal effects, and the underlying mechanisms are still poorly understood. We assessed morphological changes in retinal ganglion cells (RGCs), the affected neurons in glaucoma, and Müller cells, the major glial cells in the retina, as well as the levels of phosphorylated p38 (p-p38) and Caspase-3 in glaucoma patients. We constructed a modified chronic ocular hypertensive rat model and an oxygen-glucose deprivation (OGD) cell model. After applying NADPH and N-acetylcysteine (NAC), a precursor to cysteine, the rate-limiting substrate in GSH biosynthesis, to cells, apoptosis, axonal damage and peroxidation were reduced in the RGCs of the NAC group and p-p38 levels were decreased in the RGCs of the NADPH group, while in stimulated Müller cells cultured individually or cocultured with RGCs, gliosis and p38/MAPK, rather than JNK/MAPK, activation were inhibited. The results were more synergistic in the rat model, where either NADPH or NAC showed crossover effects on inhibiting peroxidation and p38/MAPK pathway activation. Moreover, the combination of NADPH and NAC ameliorated RGC electrophysiological function and prevented Müller cell gliosis to the greatest extent. These data illustrated conjoined mechanisms in glaucomatous RGC injury and Müller cell gliosis and suggested that NADPH and NAC collaborate as a neuroprotective and anti-inflammatory combination treatment for glaucoma and other underlying human neurodegenerative diseases.

Association of plasma lactoferrin levels with disease severity in glaucoma patients

Objective

To explore the relationship between plasma lactoferrin (Lf) and glaucoma, assessing the clinical utility of Lf in glaucoma.

Methods

A cross-sectional study involved 161 glaucoma patients and 115 healthy controls, with a follow-up of 14 subjects after approximately 2 years. Plasma Lf markers were quantified using ELISA, comparing levels between glaucoma patients and healthy controls, and analyzing plasma Lf across different glaucoma severity grades.

Results

Glaucoma patients had significantly elevated plasma Lf levels compared to healthy controls (p < 0.001). Higher plasma Lf levels correlated with more severe disease stages (HPA grades showed ρ = 0.435, p < 0.001; AGIS grades showed ρ = 0.436, p < 0.001) and reduced retinal nerve fiber layer (RNFL) thickness (RNFL thickness showed ρ = -0.204, p = 0.024). ROC curve analysis demonstrated the efficacy of glaucoma markers in differentiating early-stage from advanced glaucoma.

Conclusion

Plasma Lf levels are significantly associated with glaucoma severity and may be involved in the pathogenic progression of the disease.

GSH-responsive degradable nanodrug for glucose metabolism intervention and induction of ferroptosis to enhance magnetothermal anti-tumor therapy

The challenges associated with activating ferroptosis for cancer therapy primarily arise from obstacles related to redox and iron homeostasis, which hinder the susceptibility of tumor cells to ferroptosis. However, the specific mechanisms of ferroptosis resistance, especially those intertwined with abnormal metabolic processes within tumor cells, have been consistently underestimated. In response, we present an innovative glutathione-responsive magnetocaloric therapy nanodrug termed LFMP. LFMP consists of lonidamine (LND) loaded into PEG-modified magnetic nanoparticles with a Fe3O4 core and coated with disulfide bonds-bridged mesoporous silica shells. This nanodrug is designed to induce an accelerated ferroptosis-activating state in tumor cells by disrupting homeostasis. Under the dual effects of alternating magnetic fields and high concentrations of glutathione in the tumor microenvironment, LFMP undergoes disintegration, releasing drugs. LND intervenes in cell metabolism by inhibiting glycolysis, ultimately enhancing iron death and leading to synthetic glutathione consumption. The disulfide bonds play a pivotal role in disrupting intracellular redox homeostasis by depleting glutathione and inactivating glutathione peroxidase 4 (GPX4), synergizing with LND to enhance the sensitivity of tumor cells to ferroptosis. This process intensifies oxidative stress, further impairing redox homeostasis. Furthermore, LFMP exacerbates mitochondrial dysfunction, triggering ROS formation and lactate buildup in cancer cells, resulting in increased acidity and subsequent tumor cell death. Importantly, LFMP significantly suppresses tumor cell proliferation with minimal side effects both in vitro and in vivo, exhibiting satisfactory T2-weighted MR imaging properties. In conclusion, this magnetic hyperthermia-based nanomedicine strategy presents a promising and innovative approach for antitumor therapy.

SOX9 depletion attenuates retinal ganglion cell ferroptosis through blocking ERK/p38 signaling

BACKGROUND

Retinal ischemia-refusion (I/R) is a leading cause of irreversible blindness worldwide. This study aims to explore the regulatory role of SOX9 in retinal I/R injury, and attempts to elucidate its potential regulatory mechanism.

METHODS

Retinal I/R injury model was established in vivo, and the histological changes was examined by hematoxylin and eosin (H&E) staining and immunofluorescent assay was performed to examine SOX9 expression. Oxygenation-glucose deprivation/reoxygenation (OGD/R)-induced retinal ischemia/reperfusion (I/R) injury in 661 W cells was constructed as an in vitro cellular model of glaucoma. The production of cytokines, lactate dehydrogenase (LDH) and the antioxidant enzymes were assessed by their commercial kits. Cellular reactive oxygen species (ROS) and lipid ROS was detected using DCFH-DA and C11-BODIPY 581/591 staining, respectively. Lipid peroxidation and Fe2+ level were detected to assess the ferroptosis level. Protein expression was examined by western blot. LM22B-10, the agonist of ERK signaling, was used to pretreat 661 W cells for mechanism investigation.

RESULTS

SOX9 was aberrantly upregulated following retinal I/R injury both in vivo and in vitro. SOX9 knockdown exerted a protective role against OGD/R-triggered oxidative stress, inflammatory response and ferroptosis in 661 W cells. Further, ERK/p38 signaling was activated in 661 W cells following OGD/R induction, which was repressed by SOX9 knockdown, and the ERK signaling agonist partially counteracted the protective role of SOX9 knockdown against oxidative stress, inflammatory response and ferroptosis in OGD/R-induced 661 W cells.

CONCLUSION

Collectively, inhibiting SOX9 to block oxidative stress, inflammation and ferroptosis by inactivating ERK/p38 signaling might be effective to prevent retinal I/R injury, thereby alleviating glaucoma.

Neuroinvasive virus facilitates viral replication by employing lipid droplets to reduce arachidonic acid-induced ferroptosis

Lipids have been previously implicated in the lifecycle of neuroinvasive viruses. However, the role of lipids in programmed cell death and the relationship between programmed cell death and lipid droplets (LDs) in neuroinvasive virus infection remains unclear. Here, we found that the infection of neuroinvasive virus, such as rabies virus and encephalomyocarditis virus could enhance the LD formation in N2a cells, and decreasing LDs production by targeting diacylglycerol acyltransferase could suppress viral replication. The lipidomics analysis revealed that arachidonic acid (AA) was significantly increased after reducing LD formation by restricting diacylglycerol acyltransferase, and AA was further demonstrated to induce ferroptosis to inhibit neuroinvasive virus replication. Moreover, lipid peroxidation and viral replication inhibition could be significantly alleviated by a ferroptosis inhibitor, ferrostatin-1, indicating that AA affected neuroinvasive virus replication mainly through inducing ferroptosis. Furthermore, AA was demonstrated to activate the acyl-CoA synthetase long-chain family member 4-lysophosphatidylcholine acyltransferase 3-cytochrome P450 oxidoreductase axis to induce ferroptosis. Our findings highlight novel cross-talks among viral infection, LDs, and ferroptosis for the first time, providing a potential target for antiviral drug development.

Emerging role of ferroptosis in diabetic retinopathy: a review

BACKGROUND

Diabetic retinopathy (DR) is a significant complication of diabetes and the primary cause of blindness among working age adults globally. The development of DR is accompanied by oxidative stress, characterised by an overproduction of reactive oxygen species (ROS) and a compromised antioxidant system. Clinical interventions aimed at mitigating oxidative stress through ROS scavenging or elimination are currently available. Nevertheless, these treatments merely provide limited management over the advanced stage of the illness. Ferroptosis is a distinctive form of cell death induced by oxidative stress, which is characterised by irondependent phospholipid peroxidation.

PURPOSE

This review aims to synthesise recent experimental evidence to examine the involvement of ferroptosis in the pathological processes of DR, as well as to explicate the regulatory pathways governing oxidative stress and ferroptosis in retina.

METHODS

We systematically reviewed literature available up to 2023.

RESULTS

This review included 12 studies investigating the involvement of ferroptosis in DR.

Association between glaucoma susceptibility with combined defects in mitochondrial oxidative phosphorylation and fatty acid beta oxidation

Glaucoma is one of the leading causes of visual impairment and blindness worldwide, and is characterized by the progressive damage of retinal ganglion cells (RGCs) and the atrophy of the optic nerve head (ONH). The exact cause of RGC loss and optic nerve damage in glaucoma is not fully understood. The high energy demands of these cells imply a higher sensitivity to mitochondrial defects. Moreover, it has been postulated that the optic nerve is vulnerable towards damage from oxidative stress and mitochondrial dysfunction. To investigate this further, we conducted a pooled analysis of mitochondrial variants related to energy production, specifically focusing on oxidative phosphorylation (OXPHOS) and fatty acid β-oxidation (FAO). Our findings revealed that patients carrying non-synonymous (NS) mitochondrial DNA (mtDNA) variants within the OXPHOS complexes had an almost two-fold increased risk of developing glaucoma. Regarding FAO, our results demonstrated that longer-chain acylcarnitines (AC) tended to decrease, while shorter-chain AC tended to increase in patients with glaucoma. Furthermore, we observed that the knocking down cpt1a (a key rate-limiting enzyme involved in FAO) in zebrafish induced a degenerative process in the optic nerve and RGC, which resembled the characteristics observed in glaucoma. In conclusion, our study provides evidence that genes encoding mitochondrial proteins involved in energy metabolisms, such as OXPHOS and FAO, are associated with glaucoma. These findings contribute to a better understanding of the molecular mechanisms underlying glaucoma pathogenesis and may offer potential targets for therapeutic interventions in the future.

Inflammatory mechanisms contributing to retinal alterations in HIV infection and long-term ART

People living with HIV (PLWH) may face an increased risk of eye complications associated with ageing, chronic inflammation, and the toxicity arising from long-term antiretroviral therapy (ART). This review aims to understand how inflammatory pathways contribute to retinal alterations observed in PLWH on long-term ART. This review was conducted using four electronic database searches, namely Scopus, Hinari, Google Scholar, and PubMed; from 1996 (when ART became available) until January 2022, without language restriction. Sources from clinical trials, meta-analyses, randomised controlled trials, and systematic reviews were used. Dysregulated para-inflammation (chronic inflammation) damages the blood-retina barrier, resulting in the altered retinal immune privilege and leading to the development of retinal and blood vessel changes. There is an interplay between the effects of the disease versus ART. ART causes mitochondrial toxicity, which affects the retinal ganglion cells and retinal pigment epithelium (RPE) due to oxidative stress. Infection by HIV also affects retinal microglia, which contributes to RPE damage. Both of these mechanisms affect the blood vessels. Assessing the integrity of the inner and outer blood-retina barrier is a pivotal point in pinpointing the pathogenesis of inner retinal alterations. Optical coherence tomography is a valuable tool to assess these changes. There is a paucity of research to understand how these structural changes may affect visual function, such as contrast sensitivity and colour vision.

Identification and validation of the biomarkers related to ferroptosis in calcium oxalate nephrolithiasis

Ferroptosis is a specific type of programmed cell death characterized by iron-dependent lipid peroxidation. Understanding the involvement of ferroptosis in calcium oxalate (CaOx) stone formation may reveal potential targets for this condition. The publicly available dataset GSE73680 was used to identify 61 differentially expressed ferroptosis-related genes (DEFERGs) between normal kidney tissues and Randall's plaques (RPs) from patients with nephrolithiasis through employing weighted gene co-expression network analysis (WGCNA). The findings were validated through in vitro and in vivo experiments using CaOx nephrolithiasis rat models induced by 1% ethylene glycol administration and HK-2 cell models treated with 1 mM oxalate. Through WGCNA and the machine learning algorithm, we identified LAMP2 and MDM4 as the hub DEFERGs. Subsequently, nephrolithiasis samples were classified into cluster 1 and cluster 2 based on the expression of the hub DEFERGs. Validation experiments demonstrated decreased expression of LAMP2 and MDM4 in CaOx nephrolithiasis animal models and cells. Treatment with ferrostatin-1 (Fer-1), a ferroptosis inhibitor, partially reversed oxidative stress and lipid peroxidation in CaOx nephrolithiasis models. Moreover, Fer-1 also reversed the expression changes of LAMP2 and MDM4 in CaOx nephrolithiasis models. Our findings suggest that ferroptosis may be involved in the formation of CaOx kidney stones through the regulation of LAMP2 and MDM4.

Ripa-56 protects retinal ganglion cells in glutamate-induced retinal excitotoxic model of glaucoma

Glaucoma is a prevalent cause of blindness globally, characterized by the progressive degeneration of retinal ganglion cells (RGCs). Among various factors, glutamate excitotoxicity stands out as a significant contributor of RGCs loss in glaucoma. Our study focused on Ripa-56 and its protective effect against NMDA-induced retinal damage in mice, aiming to delve into the potential underlying mechanism. The R28 cells were categorized into four groups: glutamate (Glu), Glu + Ripa-56, Ripa-56 and Control group. After 24 h of treatment, cell death was assessed by PI / Hoechst staining. Mitochondrial membrane potential changes, apoptosis and reactive oxygen species (ROS) production were analyzed using flow cytometry. The alterations in the expression of RIP-1, p-MLKL, Bcl-2, BAX, Caspase-3, Gpx4 and SLC7A11 were examined using western blot analysis. C57BL/6j mice were randomly divided into NMDA, NMDA + Ripa-56, Ripa-56 and control groups. Histological changes in the retina were evaluated using hematoxylin and eosin (H&E) staining. RGCs survival and the protein expression changes of RIP-1, Caspase-3, Bcl-2, Gpx4 and SLC7A11 were observed using immunofluorescence. Ripa-56 exhibited a significant reduction in the levels of RIP-1, p-MLKL, Caspase-3, and BAX induced by glutamate, while promoting the expression of Bcl-2, Gpx-4, and SLC7A1 in the Ripa-56-treated group. In our study, using an NMDA-induced normal tension glaucoma mice model, we employed immunofluorescence and H&E staining to observe that Ripa-56 treatment effectively ameliorated retinal ganglion cell loss, mitigating the decrease in retinal ganglion cell layer and bipolar cell layer thickness caused by NMDA. In this study, we have observed that Ripa-56 possesses remarkable anti- necroptotic, anti-apoptotic and anti-ferroptosis properties. It demonstrates the ability to combat not only glutamate-induced excitotoxicity in R28 cells, but also NMDA-induced retinal excitotoxicity in mice. Therefore, Ripa-56 could be used as a potential retinal protective agent.

Ferroptosis in the ageing retina: A malevolent fire of diabetic retinopathy

Ageing retina is prone to ferroptosis due to the iron accumulation and impaired efficiency of intracellular antioxidant defense system. Ferroptosis acts as a cell death modality that is characterized by the iron-dependent accumulation of lipid peroxidation. Ferroptosis is distinctively different from other types of regulated cell death (RCD) at the morphological, biochemical, and genetic levels. Diabetic retinopathy (DR) is a common microvascular complication of diabetes. Its prevalence and severity increase progressively with age. Recent reports have shown that ferroptosis is implicated in the pathophysiology of DR. Under hyperglycemia condition, the endothelial cell and retinal pigment epithelium (RPE) cell will undergo ferroptosis, which contributes to the increased vascular permeability and the disrupted blood retinal barrier (BRB). The underlying etiology of DR can be attributed to the impaired BRB integrity and subsequent damages of the neurovascular units. In the absence of timely intervention, the compromised BRB can ultimately cause profound visual impairments. In particular, the ageing retina is vulnerable to ferroptosis, and hyperglycemia will accelerate the progression of this pathological process. In this article, we discuss the contributory role of ferroptosis in DR pathogenesis, and summarize recent therapeutic trials that targeting the ferroptosis. Further study on the ferroptosis mediated damage would enrich our knowledge of DR pathology, and promote the development of clinical treatment for this degenerative retinopathy.

Signalling pathways and cell death mechanisms in glaucoma: Insights into the molecular pathophysiology

Glaucoma is a complex multifactorial eye disease manifesting in retinal ganglion cell (RGC) death and optic nerve degeneration, ultimately causing irreversible vision loss. Research in recent years has significantly enhanced our understanding of RGC degenerative mechanisms in glaucoma. It is evident that high intraocular pressure (IOP) is not the only contributing factor to glaucoma pathogenesis. The equilibrium of pro-survival and pro-death signalling pathways in the retina strongly influences the function and survival of RGCs and optic nerve axons in glaucoma. Molecular evidence from human retinal tissue analysis and a range of experimental models of glaucoma have significantly contributed to unravelling these mechanisms. Accumulating evidence reveals a wide range of molecular signalling pathways that can operate -either alone or via intricate networks - to induce neurodegeneration. The roles of several molecules, including neurotrophins, interplay of intracellular kinases and phosphates, caveolae and adapter proteins, serine proteases and their inhibitors, nuclear receptors, amyloid beta and tau, and how their dysfunction affects retinal neurons are discussed in this review. We further underscore how anatomical alterations in various animal models exhibiting RGC degeneration and susceptibility to glaucoma-related neuronal damage have helped to characterise molecular mechanisms in glaucoma. In addition, we also present different regulated cell death pathways that play a critical role in RGC degeneration in glaucoma.

Understanding the complex genetics and molecular mechanisms underlying glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide. Currently the only effective treatment for glaucoma is to reduce the intraocular pressure, which can halt the progression of the disease. Highlighting the importance of identifying individuals at risk of developing glaucoma and those with early-stage glaucoma will help patients receive treatment before sight loss. However, some cases of glaucoma do not have raised intraocular pressure. In fact, glaucoma is caused by a variety of different mechanisms and has a wide range of different subtypes. Understanding other risk factors, the underlying mechanisms, and the pathology of glaucoma might lead to novel treatments and treatment of underlying diseases. In this review we present the latest research into glaucoma including the genetics and molecular basis of the disease.

GGT1 Suppresses the Development of Ferroptosis and Autophagy in Mouse Retinal Ganglion Cell Through Targeting GCLC

Background

Glaucoma is a neurodegenerative disorder characterized with optic nerve injury and the loss of retinal ganglion cells (RGCs). Ferroptosis has been proved to be associated with the degradation of RGCs. The aim of this study is to elucidate the relationship between ferroptosis and glaucoma pathogenesis, and unveil the underlying mechanism.

Methods

Methyl thiazolyl tetrazolium (MTT) assay was used to evaluate the proliferation of RGCs. The accumulation of cellular iron was measured by Iron assay kit, and the level of reactive oxygen species (ROS) was detected by fluorescence probe. The mitochondrial morphology and autophagosomes were analysed by using transmission electron microscopy (TEM). The contents of glutathione (GSH) and malondialdehyde (MDA) were tested by a GSH assay kit and an MDA detection kit, respectively. The expression of autophagy-related proteins was detected by Western blotting.

Results

A serious cell damage, aberrant iron homeostasis, and oxidative stress was shown in RGC-5 after oxygen-glucose deprivation/reoxygenation (OGD/R) treatment and gamma-Glutamyl transpeptidase 1 (GGT1) knockdown, but these effects were significantly alleviated by overexpression of GGT1 or ferroptosis inhibitors. The TEM and immunofluorescent results indicated that mitochondria impairment and autophagosome accumulation in OGD/R-treated cells was improved after GGT1 overexpression, while the phenomenon in GGT1-silenced cells was aggravated. Furthermore, we found that GGT1 can interact with glutamate cysteine ligase catalytic subunit (GCLC) to inhibit autophagy and ferroptosis in RGC-5 cells.

Conclusion

GGT1 represses autophagy in RGC-5 cells by targeting GCLC, which further restrains the development of ferroptosis in cells.

Mesenchymal stem cell attenuates spinal cord injury by inhibiting mitochondrial quality control-associated neuronal ferroptosis

Ferroptosis is a newly discovered form of iron-dependent oxidative cell death and drives the loss of neurons in spinal cord injury (SCI). Mitochondrial damage is a critical contributor to neuronal death, while mitochondrial quality control (MQC) is an essential process for maintaining mitochondrial homeostasis to promote neuronal survival. However, the role of MQC in neuronal ferroptosis has not been clearly elucidated. Here, we further demonstrate that neurons primarily suffer from ferroptosis in SCI at the single-cell RNA sequencing level. Mechanistically, disordered MQC aggravates ferroptosis through excessive mitochondrial fission and mitophagy. Furthermore, mesenchymal stem cells (MSCs)-mediated mitochondrial transfer restores neuronal mitochondria pool and inhibits ferroptosis through mitochondrial fusion by intercellular tunneling nanotubes. Collectively, these results not only suggest that neuronal ferroptosis is regulated in an MQC-dependent manner, but also fulfill the molecular mechanism by which MSCs attenuate neuronal ferroptosis at the subcellular organelle level. More importantly, it provides a promising clinical translation strategy based on stem cell-mediated mitochondrial therapy for mitochondria-related central nervous system disorders.

Melatonin Ameliorates Hepatic Ferroptosis in NAFLD by Inhibiting ER Stress via the MT2/cAMP/PKA/IRE1 Signaling Pathway

Ferroptosis, an iron-dependent cell death form, has recently been observed in the development of non-alcoholic fatty liver disease (NAFLD). Melatonin (Mel) shows potential benefits for preventing and treating liver diseases. Whether and how Mel ameliorates hepatic ferroptosis in NAFLD is not fully understood. Here we established a mouse model of NAFLD induced by long-term high-fat diet (HFD) feeding. We found that Mel treatment ameliorated global metabolic abnormalities and inhibited the progression of NAFLD in mice. Most importantly, Mel supplementation significantly improved HFD-induced iron homeostasis disorders in the liver, including iron overload and ferritin transport disorders. For another, Mel ameliorated HFD-induced hepatic lipid peroxidation. The recuperative role of exogenous Mel on hepatocyte ferroptosis was also observed in PA- or Erastin-treated HepG2 cells. Mechanistically, MT2, but not MT1, was involved in the effect of Mel. Furthermore, Mel treatment inhibited HFD or Erastin-activated ER stress and activated the PKA/IRE1 signaling pathway. Co-expression of p-PKA and p-IRE1 was enhanced by the MT2 antagonist. Inhibitions of PKA and IRE1 respectively improved hepatocyte ferroptosis, and activations of cAMP/PKA reversed Mel's effect on ferroptosis. Collectively, these findings suggest that exogenous Mel inhibits hepatic ferroptosis in NAFLD by ameliorating ER stress through the MT2/cAMP/PKA/IRE1 pathway, proving that Mel is a promising candidate drug for the treatment of hepatic ferroptosis in NAFLD.

Exploring the current use of animal models in glaucoma drug discovery: where are we in 2023?

INTRODUCTION

Animal models are widely used in glaucoma-related research. Since the elevated intraocular pressure (IOP) is a major risk factor underlying the disease pathogenesis, animal models with high IOP are commonly used. However, models are also used to represent the clinical context of glaucomatous changes developing despite a normal IOP.

AREAS COVERED

Herein, the authors discuss the various factors that contribute to the quality of studies using animal models based on the evaluation of studies published in 2022. The factors affecting the quality of studies using animal models, such as the animal species, age, and sex, are discussed, along with various methods and outcomes of studies involving different animal models of glaucoma.

EXPERT OPINION

Translating animal research data to clinical applications remains challenging. Our observations in this review clearly indicate that many studies lack scientific robustness not only in their experiment conduct but also in data analysis, interpretation, and presentation. In this context, ensuring the internal validity of animal studies is the first step in quality assurance. External validity, however, is more challenging, and steps should be taken to satisfy external validity at least to some extent.