Auranofin Mediates Mitochondrial Dysregulation and Inflammatory Cell Death in Human Retinal Pigment Epithelial Cells: Implications of Retinal Neurodegenerative Diseases

The important role of ferroptosis in inflammatory bowel disease

Ferroptosis is a type of regulated cell death that occurs due to the iron-dependent accumulation of lethal reactive oxygen species (ROS) from lipids. Ferroptosis is characterized by distinct morphological, biochemical, and genetic features that differentiate it from other regulated cell death (RCD) types, which include apoptosis, various necrosis types, and autophagy. Recent reports show that ferritin formation is correlated to many disorders, such as acute injury, infarction, inflammation, and cancer. Iron uptake disorders have also been associated with intestinal epithelial dysfunction, particularly inflammatory bowel disease (IBD). Studies of iron uptake disorders may provide new insights into the pathogenesis of IBD, thereby improving the efficacy of medical interventions. This review presents an overview of ferroptosis, elucidating its fundamental mechanisms and highlighting its significant involvement in IBD.

Repurposing auranofin and meclofenamic acid as energy-metabolism inhibitors and anti-cancer drugs

OBJECTIVE

Cytotoxicity of the antirheumatic drug auranofin (Aur) and the non-steroidal anti-inflammatory drug meclofenamic acid (MA) on several cancer cell lines and isolated mitochondria was examined to assess whether these drugs behave as oxidative phosphorylation inhibitors.

METHODS

The effect of Aur or MA for 24 h was assayed on metastatic cancer and non-cancer cell proliferation, energy metabolism, mitophagy and metastasis; as well as on oxygen consumption rates of cancer and non-cancer mitochondria.

RESULTS

Aur doses in the low micromolar range were required to decrease proliferation of metastatic HeLa and MDA-MB-231 cells, whereas one or two orders of magnitude higher levels were required to affect proliferation of non-cancer cells. MA doses required to affect cancer cell growth were one order of magnitude higher than those of Aur. At the same doses, Aur impaired oxidative phosphorylation in isolated mitochondria and intact cells through mitophagy induction, as well as glycolysis. Consequently, cell migration and invasiveness were severely affected. The combination of Aur with very low cisplatin concentrations promoted that the effects on cellular functions were potentiated.

CONCLUSION

Aur surges as a highly promising anticancer drug, suggesting that efforts to establish this drug in the clinical treatment protocols are warranted and worthy to undertake.

Progress in Research on the Role of the Thioredoxin System in Chemical Nerve Injury

(1) Background: Various factors, such as oxidative stress, mitochondrial dysfunction, tumors, inflammation, trauma, immune disorders, and neuronal toxicity, can cause nerve damage. Chemical nerve injury, which results from exposure to toxic chemicals, has garnered increasing research attention. The thioredoxin (Trx) system, comprising Trx, Trx reductase, nicotinamide adenine dinucleotide phosphate, and Trx-interacting protein (TXNIP; endogenous Trx inhibitor), helps maintain redox homeostasis in the central nervous system. The dysregulation of this system can cause dementia, cognitive impairment, nerve conduction disorders, movement disorders, and other neurological disorders. Thus, maintaining Trx system homeostasis is crucial for preventing or treating nerve damage. (2) Objective: In this review study, we explored factors influencing the homeostasis of the Trx system and the involvement of its homeostatic imbalance in chemical nerve injury. In addition, we investigated the therapeutic potential of the Trx system-targeting active substances against chemical nerve injury. (3) Conclusions: Chemicals such as morphine, metals, and methylglyoxal interfere with the activity of TXNIP, Trx, and Trx reductase, disrupting Trx system homeostasis by affecting the phosphatidylinositol-3-kinase/protein kinase B, extracellular signal-regulated kinase, and apoptotic signaling-regulated kinase 1/p38 mitogen-activated protein kinase pathways, thereby leading to neurological disorders. Active substances such as resveratrol and lysergic acid sulfide mitigate the symptoms of chemical nerve injury by regulating the Ras/Raf1/extracellular signal-regulated kinase pathway and the miR-146a-5p/TXNIP axis. This study may guide the development of Trx-targeting modulators for treating neurological disorders and chemical nerve injuries.

Targeting inflammasomes and pyroptosis in retinal diseases-molecular mechanisms and future perspectives

Retinal diseases encompass various conditions associated with sight-threatening immune responses and are leading causes of blindness worldwide. These diseases include age-related macular degeneration, diabetic retinopathy, glaucoma and uveitis. Emerging evidence underscores the vital role of the innate immune response in retinal diseases, beyond the previously emphasized T-cell-driven processes of the adaptive immune system. In particular, pyroptosis, a newly discovered programmed cell death process involving inflammasome formation, has been implicated in the loss of membrane integrity and the release of inflammatory cytokines. Several disease-relevant animal models have provided evidence that the formation of inflammasomes and the induction of pyroptosis in innate immune cells contribute to inflammation in various retinal diseases. In this review article, we summarize current knowledge about the innate immune system and pyroptosis in retinal diseases. We also provide insights into translational targeting approaches, including novel drugs countering pyroptosis, to improve the diagnosis and treatment of retinal diseases.

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.

Non-Apoptotic Programmed Cell Death as Targets for Diabetic Retinal Neurodegeneration

Diabetic retinopathy (DR) remains the leading cause of blindness among the global working-age population. Emerging evidence underscores the significance of diabetic retinal neurodegeneration (DRN) as a pivotal biomarker in the progression of vasculopathy. Inflammation, oxidative stress, neural cell death, and the reduction in neurotrophic factors are the key determinants in the pathophysiology of DRN. Non-apoptotic programmed cell death (PCD) plays a crucial role in regulating stress response, inflammation, and disease management. Therapeutic modalities targeting PCD have shown promising potential for mitigating DRN. In this review, we highlight recent advances in identifying the role of various PCD types in DRN, with specific emphasis on necroptosis, pyroptosis, ferroptosis, parthanatos, and the more recently characterized PANoptosis. In addition, the therapeutic agents aimed at the regulation of PCD for addressing DRN are discussed.

USP48 deubiquitination stabilizes SLC1A5 to inhibit retinal pigment epithelium cell inflammation, oxidative stress and ferroptosis in the progression of diabetic retinopathy

BACKGROUND

Diabetic retinopathy is one of the complications of diabetes mellitus. The aim of this study was to explore the effects of ubiquitin-specific protease 48 (USP48) and its underlying mechanisms in the development of diabetic retinopathy.

METHODS

CCK-8 assay, EdU assay, and flow cytometry were used to measure the proliferative ability and the apoptotic rate of ARPE-19 cells, respectively. ELISA kits were utilized to assess the levels of inflammatory cytokines. The levels of Fe2+, ROS and MDA were detected using the corresponding biochemical kits. The protein expression of USP48 and SLC1A5 was examined through western blot. The mRNA level of SLC1A5 was determined using RT-qPCR. The interaction relationship between USP48 and SLC1A5 was evaluated using Co-IP assay.

RESULTS

High glucose (HG) treatment significantly inhibited cell proliferation and elevated cell apoptosis, inflammation, ferroptosis and oxidative stress in ARPE-19 cells. HG treatment-caused cell damage was hindered by USP48 or SLC1A5 overexpression in ARPE-19 cells. Fer-1 treatment improved HG-caused cell damage in ARPE-19 cells, which was blocked by USP48 knockdown. Moreover, USP48 knockdown decreased SLC1A5 expression. SLC1A5 downregulation reversed the improvement effects of USP48 upregulation on cell damage in HG-treated ARPE-19 cells.

CONCLUSION

USP48 overexpression deubiquitinated SLC1A5 to elevate cell proliferation and suppress cell apoptosis, inflammation, ferroptosis and oxidative stress in HG-triggered ARPE-19 cells, thereby inhibiting the progression of diabetic retinopathy.

MiR-204-5p may regulate oxidative stress in myopia

The mechanisms underlying myopia remain not fully understood. We proposed to examine the function and underlying mechanisms of miR-204-5p in myopia development. The miR-204-5p expression level was assessed in the vitreous humor (VH) of a cohort consisting of 11 patients with high myopia (HM) and 16 control patients undergoing vitrectomy. Then the functional implications of miR-204-5p in ARPE-19 cells were assessed. Thioredoxin-interacting protein (TXNIP) was found as a possible target of miR-204-5p through mRNA sequencing, and its interaction with miR-204-5p was confirmed employing luciferase assay and western blotting. Furthermore, the miR-204-5p function in regulating oxidative stress was examined by measuring reactive oxygen species (ROS) accumulation. The results indicated a significant reduction of miR-204-5p in the VH of HM patients. Overexpression of miR-204-5p suppressed cell proliferation, migration, invasion, and apoptosis in ARPE-19 cells. The direct targeting of miR-204-5p on TXNIP has been confirmed, and its downregulation mediated the miR-204-5p impacts on ARPE-19 cells. Moreover, miR-204-5p overexpression significantly reduced ROS accumulation by targeting TXNIP. Our findings revealed the possible contribution of the miR-204-5p/TXNIP axis in myopia development by regulating oxidative stress, which may provide new targets to combat this prevalent and debilitating condition.

Copper Exposure Induced Chicken Hepatotoxicity: Involvement of Ferroptosis Mediated by Lipid Peroxidation, Ferritinophagy, and Inhibition of FSP1-CoQ10 and Nrf2/SLC7A11/GPX4 Axis

Copper (Cu) is one of the most significant trace elements in the body, but it is also a widespread environmental toxicant health. Ferroptosis is a newly identified programmed cell death, which involves various heavy metal-induced organ toxicity. Nevertheless, the role of ferroptosis in Cu-induced hepatotoxicity remains poorly understood. In this study, we found that 330 mg/kg Cu could disrupt the liver structure and cause characteristic morphological changes in mitochondria associated with ferroptosis. Additionally, Cu treatment increased MDA (malondialdehyde) and LPO (lipid peroxide) production while reducing GSH (reduced glutathione) content and GCL (glutamate cysteine ligase) activity. However, it is noticeable that there were no appreciable differences in liver iron content and key indicators of iron metabolism. Meanwhile, our further investigation found that 330 mg/kg Cu-exposure changed multiple ferroptosis-related indicators in chicken livers, including inhibition of the expression of SLC7A11, GPX4, FSP1, and COQ10B, whereas enhances the levels of ACLS4, LPCAT3, and LOXHD1. Furthermore, the changes in the expression of NCOA4, TXNIP, and Nrf2/Keap1 signaling pathway-related genes and proteins also further confirmed 330 mg/kg Cu exposure-induced ferroptosis. In conclusion, our results indicated that ferroptosis may play essential roles in Cu overload-induced liver damage, which offered new insights into the pathogenesis of Cu-induced hepatotoxicity.

Ferroptosis as a potential therapeutic target for age-related macular degeneration

Cell death plays a crucial part in the process of age-related macular degeneration (AMD), but its mechanisms remain elusive. Accumulating evidence suggests that ferroptosis, a novel form of regulatory cell death characterized by iron-dependent accumulation of lipid hydroperoxides, has a crucial role in the pathogenesis of AMD. Numerous studies have suggested that ferroptosis participates in the degradation of retinal cells and accelerates the progression of AMD. Furthermore, inhibitors of ferroptosis exhibit notable protective effects in AMD, underscoring the significance of ferroptosis as a pivotal mechanism in the death of retinal cells during the process of AMD. This review aims to summarize the molecular mechanisms of ferroptosis in AMD, enumerate potential inhibitors and discuss the challenges and future opportunities associated with targeting ferroptosis as a therapeutic strategy, providing important information references and insights for the prevention and treatment of AMD.

TXNIP-NLRP3-GSDMD axis-mediated inflammation and pyroptosis of islet β-cells is involved in cigarette smoke-induced hyperglycemia, which is alleviated by andrographolide

Epidemiologic surveys have indicated that cigarette smoking is an important risk factor for diabetes, but its mechanisms remain unclear. Andrographolide, an herb traditionally utilized in medicine, provides anti-inflammatory benefits for various diseases. In the present work, 265 patients with Type 2 diabetes (T2D) were investigated, and male C57BL/6 mice were exposed to cigareete smoke (CS) and/or to intraperitoneally injected andrographolide for 3 months. To elucidate the mechanism of CS-induced hyperglycemia and the protective mechanism of andrographolide, MIN6 cells were exposed to cigarette smoke extract (CSE) and/or to andrographolide. Our data from 265 patients with T2D showed that urinary creatinine and serum inflammatory cytokines (interleukin 6 (IL-6), IL-8, IL-1β, and tumor necrosis factor α (TNF-α)) increased with smoking pack-years. In a mouse model, CS induced hyperglycemia, decreased insulin secretion, and elevated inflammation and pyroptosis in β-cells of mice. Treatment of mice with andrographolide preserved pancreatic function by reducing the expression of inflammatory cytokines; the expression of TXNIP, NLRP3, cleaved caspase 1, IL-1β; and the N-terminal of gasdermin D (GSDMD) protein. For MIN6 cells, CSE caused increasing secretion of the inflammatory cytokines IL-6 and IL-1β, and the expression of TXNIP and pyroptosis-related proteins; however, andrographolide alleviated these changes. Furthermore, silencing of TXNIP showed that the blocking effect of andrographolide may be mediated by TXNIP. In sum, our results indicate that CS induces hyperglycemia through TXNIP-NLRP3-GSDMD axis-mediated inflammation and pyroptosis of islet β-cells and that andrographolide is a potential therapeutic agent for CS-induced hyperglycemia.

Alleviated NCOA4-mediated ferritinophagy protected RA FLSs from ferroptosis in lipopolysaccharide-induced inflammation under hypoxia

OBJECTIVE

Ferroptosis is a reactive oxygen species (ROS)- and iron-dependent form of non-apoptotic cell death process. Previous studies have demonstrated that ferroptosis participates in the development of inflammatory arthritis. However, the role of ferroptosis in rheumatoid arthritis (RA) inflammatory hypoxic joints remains unclear. This study sought to explore the underlying mechanism of ferroptosis on lipopolysaccharide (LPS)-induced RA fibroblast-like synoviocytes (FLSs).

METHODS

FLSs, isolated from patients with RA, were treated with LPS and ferroptosis inducer (erastin and RSL-3), and ferroptosis inhibitor (Fer-1 and DFO), respectively. The cell viability was measured by CCK-8. The cell death was detected by flow cytometer. The proteins level were tested by Western blot. The cytosolic ROS and lipid peroxidation were determined using DCFH-DA and C11-BODIPY581/591 fluorescence probes, respectively. The small interfering RNA (siRNA) was used to knock down related proteins. The levels of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), iron, inflammatory cytokines (IL6 and IL8), and LDH were analyzed by commercial kits.

RESULTS

Ferroptosis was activated by LPS in RA FLS with increased cellular damage, ROS and lipid peroxidation, intracellular Fe and IL8, which can be further amplified by ferroptosis inducer (erastin and RSL-3) and inhibited by ferroptosis inhibitor (Fer-1 and DFO). Mechanistically, LPS triggered ferroptosis via NCOA4-mediated ferritinophagy in RA FLSs, and knockdown of NCOA4 strikingly prevent the process of ferroptosis. Intriguingly, LPS-induced RA FLSs became insensitive to ferroptosis and NCOA4-mediated ferritinophagy under hypoxia compared with normoxia. Knockdown of HIF-1α reverted ferroptosis and ferritinophagy evoking by LPS-induced RA FLSs inflammation under hypoxia. In addition, low dose of auranofin (AUR) induced re-sensitization of ferroptosis and ferritinophagy through inhibiting the expression of HIF-1α under hypoxia.

CONCLUSIONS

NCOA4-mediated ferritinophagy was a key driver of ferroptosis in inflammatory RA FLSs. The suppression of NCOA4-mediated ferritinophagy protected RA FLSs from ferroptosis in LPS-induced inflammation under hypoxia. Targeting HIF-1α/NCOA4 and ferroptosis could be an effective and valuable therapeutic strategy for synovium hyperplasia in the patients with RA.

Natural compounds efficacy in Ophthalmic Diseases: A new twist impacting ferroptosis

Ferroptosis, a distinct form of cell death, is characterized by the iron-mediated oxidation of lipids and is finely controlled by multiple cellular metabolic pathways. These pathways encompass redox balance, iron regulation, mitochondrial function, as well as amino acid, lipid, and sugar metabolism. Additionally, various disease-related signaling pathways also play a role in the regulation of ferroptosis. In recent years, with the introduction of the concept of ferroptosis and the deepening of research on its mechanism, ferroptosis is closely related to various biological conditions of eye diseases, including eye organ development, aging, immunity, and cancer. This article reviews the development of the concept of ferroptosis, the mechanism of ferroptosis, and its latest research progress in ophthalmic diseases and reviews the research on ferroptosis in ocular diseases within the framework of metabolism, active oxygen biology, and iron biology. Key regulators and mechanisms of ferroptosis in ocular diseases introduce important concepts and major open questions in the field of ferroptosis and related natural compounds. It is hoped that in future research, further breakthroughs will be made in the regulation mechanism of ferroptosis and the use of ferroptosis to promote the treatment of eye diseases. At the same time, natural compounds may be the direction of new drug development for the potential treatment of ferroptosis in the future. Open up a new way for clinical ophthalmologists to research and prevent diseases.

Ferroptosis and its emerging role in kidney stone formation

Kidney stone is a common and highly recurrent disease in urology, and its pathogenesis is associated with various factors. However, its precise pathogenesis is still unknown. Ferroptosis describes a form of regulated cell death that is driven by unrestricted lipid peroxidation, which does not require the activation of caspase and can be suppressed by iron chelators, lipophilic antioxidants, inhibitors of lipid peroxidation, and depletion of polyunsaturated fatty acids. Recent studies have shown that ferroptosis plays a crucial role in kidney stone formation. An increasing number of studies have shown that calcium oxalate, urate, phosphate, and selenium deficiency induce ferroptosis and promote kidney stone formation through mechanisms such as oxidative stress, endoplasmic reticulum stress, and autophagy. We also offered a new direction for the downstream mechanism of ferroptosis in kidney stone formation based on the "death wave" phenomenon. We reviewed the emerging role of ferroptosis in kidney stone formation and provided new ideas for the future treatment and prevention of kidney stones.

Targeting Ferroptosis Promotes Functional Recovery by Mitigating White Matter Injury Following Acute Carbon Monoxide Poisoning

Survivors experiencing acute carbon monoxide poisoning (ACMP) tend to develop white matter injury (WMI). The mechanism of ACMP-induced WMI remains unclear. Considering the role of ferroptosis in initiating oligodendrocyte damage to deteriorate WMI, exploring therapeutic options to attenuate ferroptosis is a feasible approach to alleviating WMI. Our results indicated that ACMP induced accumulation of iron and reactive oxygen species (ROS) eventually leading to WMI and motor impairment after ACMP. Furthermore, ferrostatin-1 reduced iron and ROS deposition to alleviate ferroptosis, thereafter reducing WMI to promote the recovery of motor function. The nuclear factor erythroid-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway was found to be involved in alleviating ferroptosis as seen with the administration of ferrostatin-1. The present study rationalizes that targeting ferroptosis to alleviate WMI is a feasible therapeutic strategy for managing ACMP.

Puerarin Attenuates Iron Overload-Induced Ferroptosis in Retina through a Nrf2-Mediated Mechanism

SCOPE

Age-related increases in retinal iron are involved in the development of retinal degeneration. The recently discovered iron-dependent mechanism of cell death known as ferroptosis has been linked to a wide range of pathologies. However, its role in iron overload-induced retinal degeneration is still uncertain. Puerarin has been associated with retinal protection. The purpose of this research is to determine how puerarin prevents retinal ferroptosis under iron overload conditions.

METHODS AND RESULTS

Models of iron overload in Kunming mice, 661W cell, and ARPE-19 cell are established. Increased iron deposition significantly worsens retinal pathology, decreases cell viability, and induces ferroptotic changes. Puerarin mitigates iron overload-induced ferroptosis by decreasing excessive iron through the regulation of iron handling proteins and lowering lipid peroxidation through the inhibition of cyclooxygenase 2 expression and activation of the nuclear factor-E2-related factor 2 (Nrf2) signaling pathway and downstream ferroptosis-related proteins (solute carrier family 7 member 11, glutathione peroxidase 4 and heme oxygenase-1). The protective effect of puerarin on ferroptosis is diminished by the Nrf2-specific inhibitor ML385.

CONCLUSION

These findings suggest targeting ferroptosis may be a novel strategy for the management of retinal degeneration. Puerarin may exert some of its ocular benefits by attenuating ferroptosis.

Pipecolic acid mitigates ferroptosis in diabetic retinopathy by regulating GPX4-YAP signaling

Diabetic retinopathy (DR) is currently recognized as the leading cause of end-stage eye disease. Pipecolic acid, a metabolite, has a significant regulatory effect on several pathological processes. However, the exact mechanism by which it causes damage in diabetic retinopathy is unknown. Between September 2021 and December 2022, 40 patients were retrospectively examined and divided into two groups: the healthy group (n = 20) and the DR group (n = 20). Metabolomic analysis found that pipecolic acid plays an important role in this process. Streptozotocin-induced diabetic mice and high-glucose cultured human retinal capillary endothelial cells (HRCECs) were then treated with pipecolic acid. Several oxidative stress measurements and RNA sequencing of retinal cells were tested. A gene interaction study was conducted using bioinformatics. Comparison of serological metabolites between healthy volunteers and DR patients showed that pipecolic acid was significantly lower in DR patients, and there was a negative correlation between the level of pipecolic acid with blood glucose and glycated hemoglobin. Yes-associated protein (YAP) mRNA, Malondialdehyde (MDA), and reactive oxygen species (ROS) levels were significantly higher in diabetic mice, but glutathione peroxidase (GSH-Px) levels were significantly lower. Pipecolic acid significantly alleviated oxidative stress and YAP expression. The number of vascular tubes was significantly higher in the DR group, and pipecolic acid treatment significantly reduced tube formation. RNA-Sequencing analysis revealed that YAP and glutathione-dependent lipid hydroperoxidase glutathione peroxidase 4 (GPX4) expression was reduced, and functional enrichment analysis revealed that ferroptosis and Hippo signaling pathways play an important role in this process. Additionally, pipecolic acid's ability to improve DR is diminished after YAP and GPX4 ablation. This study found that pipecolic acid, as a metabolite, may impede the progression of DR by inhibiting the YAP-GPX4 signaling pathway.

Spotlight on iron and ferroptosis: research progress in diabetic retinopathy

Iron, as the most abundant metallic element within the human organism, is an indispensable ion for sustaining life and assumes a pivotal role in governing glucose and lipid metabolism, along with orchestrating inflammatory responses. The presence of diabetes mellitus (DM) can induce aberrant iron accumulation within the corporeal system. Consequentially, iron overload precipitates a sequence of important adversities, subsequently setting in motion a domino effect wherein ferroptosis emerges as the utmost pernicious outcome. Ferroptosis, an emerging variant of non-apoptotic regulated cell death, operates independently of caspases and GSDMD. It distinguishes itself from alternative forms of controlled cell death through distinctive morphological and biochemical attributes. Its principal hallmark resides in the pathological accrual of intracellular iron and the concomitant generation of iron-driven lipid peroxides. Diabetic retinopathy (DR), established as the predominant cause of adult blindness, wields profound influence over the well-being and psychosocial strain experienced by afflicted individuals. Presently, an abundance of research endeavors has ascertained the pervasive engagement of iron and ferroptosis in the microangiopathy inherent to DR. Evidently, judicious management of iron overload and ferroptosis in the early stages of DR bears the potential to considerably decelerate disease progression. Within this discourse, we undertake a comprehensive exploration of the regulatory mechanisms governing iron homeostasis and ferroptosis. Furthermore, we expound upon the subsequent detriments induced by their dysregulation. Concurrently, we elucidate the intricate interplay linking iron overload, ferroptosis, and DR. Delving deeper, we engage in a comprehensive deliberation regarding strategies to modulate their influence, thereby effecting prospective interventions in the trajectory of DR's advancement or employing them as therapeutic modalities.

Reduction of high glucose-induced oxidative injury in human retinal pigment epithelial cells by sarsasapogenin through inhibition of ROS generation and inactivation of NF-κB/NLRP3 inflammasome pathway

BACKGROUND

Hyperglycemia-induced accumulation of reactive oxygen species (ROS) is a major risk factor for diabetic retinopathy (DR). Sarsasapogenin is a natural steroidal saponin that is known to have excellent antidiabetic effects and improve diabetic complications, but its potential efficacy and mechanism for DR are unknown.

OBJECTIVES

The current study was designed to explore whether sarsasapogenin inhibits hyperglycemia-induced oxidative stress in human retinal pigment epithelial (RPE) ARPE-19 cells and to elucidate the molecular mechanisms.

METHODS

To mimic hyperglycemic conditions, ARPE-19 cells were cultured in medium containing high glucose (HG). The suppressive effects of sarsasapogenin on HG-induced cell viability reduction, apoptosis and ROS production were investigated. In addition, the relevance of the nuclear factor-kappa B (NF-κB)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome signaling pathway was explored to investigate the mechanism of antioxidant and anti-inflammatory activity of sarsasapogenin.

RESULTS

Sarsasapogenin significantly alleviated cytotoxicity and apoptosis in HG-treated ARPE-19 cells through inhibition of intracellular ROS generation. Sarsasapogenin also effectively attenuated HG-induced excess accumulation of mitochondrial superoxide, reduction of glutathione content, and inactivation of manganese superoxide dismutase and glutathione peroxidase. The HG condition markedly increased the expression and maturation of interleukin (IL)-1β and IL-18 through the activation of the NF-kB signaling pathway, whereas sarsasapogenin reversed these effects. Moreover, although the expression of NLRP3 inflammasome multiprotein complex molecules was increased in ARPE-19 cells cultured under HG conditions, their levels remained similar to the control group in the presence of sarsasapogenin.

CONCLUSION

Sarsasapogenin could protect RPE cells from HG-induced injury by inhibiting ROS generation and NF-κB/NLRP3 inflammasome pathway, suggesting its potential as a therapeutic agent to improve the symptoms of DR.

β-Asarone Alleviates High-Glucose-Induced Oxidative Damage via Inhibition of ROS Generation and Inactivation of the NF-κB/NLRP3 Inflammasome Pathway in Human Retinal Pigment Epithelial Cells

Diabetic retinopathy (DR) is the leading cause of vision loss and a major complication of diabetes. Hyperglycemia-induced accumulation of reactive oxygen species (ROS) is an important risk factor for DR. β-asarone, a major component of volatile oil extracted from Acori graminei Rhizoma, exerts antioxidant effects; however, its efficacy in DR remains unknown. In this study, we investigated whether β-asarone inhibits high-glucose (HG)-induced oxidative damage in human retinal pigment epithelial (RPE) ARPE-19 cells. We found that β-asarone significantly alleviated cytotoxicity, apoptosis, and DNA damage in HG-treated ARPE-19 cells via scavenging of ROS generation. β-Asarone also significantly attenuated the excessive accumulation of lactate dehydrogenase and mitochondrial ROS by increasing the manganese superoxide dismutase and glutathione activities. HG conditions markedly increased the release of interleukin (IL)-1β and IL-18 and upregulated their protein expression and activation of the nuclear factor-kappa B (NF-κB) signaling pathway, whereas β-asarone reversed these effects. Moreover, expression levels of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome multiprotein complex molecules, including thioredoxin-interacting protein, NLRP3, apoptosis-associated speck-like protein containing a caspase-recruitment domain, and cysteinyl aspartate-specific proteinase-1, were increased in ARPE-19 cells under HG conditions. However, their expression levels remained similar to those in the control group in the presence of β-asarone. Therefore, β-asarone protects RPE cells from HG-induced injury by blocking ROS generation and NF-κB/NLRP3 inflammasome activation, indicating its potential as a therapeutic agent for DR treatment.

Immune Fingerprint in Diabetes: Ocular Surface and Retinal Inflammation

Diabetes is a prevalent global health issue associated with significant morbidity and mortality. Diabetic retinopathy (DR) is a well-known inflammatory, neurovascular complication of diabetes and a leading cause of preventable blindness in developed countries among working-age adults. However, the ocular surface components of diabetic eyes are also at risk of damage due to uncontrolled diabetes, which is often overlooked. Inflammatory changes in the corneas of diabetic patients indicate that inflammation plays a significant role in diabetic complications, much like in DR. The eye's immune privilege restricts immune and inflammatory responses, and the cornea and retina have a complex network of innate immune cells that maintain immune homeostasis. Nevertheless, low-grade inflammation in diabetes contributes to immune dysregulation. This article aims to provide an overview and discussion of how diabetes affects the ocular immune system's main components, immune-competent cells, and inflammatory mediators. By understanding these effects, potential interventions and treatments may be developed to improve the ocular health of diabetic patients.

1,8-Cineole ameliorates diabetic retinopathy by inhibiting retinal pigment epithelium ferroptosis via PPAR-γ/TXNIP pathways

1,8-Cineole, the main component of volatile oil in aromatic plants, has diverse pharmacological properties, including antioxidant, anti-inflammatory, and anti-cancer properties. Diabetic retinopathy (DR) is a common microvascular complication of diabetes mellitus (DM). Here, we investigated the protective effect of 1,8-cineole on DR and found that 1,8-cineole treatment could alter the expression of several genes in both high glucose (HG)-induced ARPE-19 cells and retinal tissues of DM mice, as well as inhibit ferroptosis. Subsequent investigations into the molecular mechanisms underlying this inhibition revealed that expression of thioredoxin-interacting protein (TXNIP) was significantly upregulated while that of peroxisome proliferator-activated receptor γ (PPAR-γ) was significantly downregulated in HG-induced ARPE-19 cells, and treatment with 1,8-cineole could effectively reverse these changes. Treatment with a PPAR-γ pharmacological agonist (rosiglitazone), alone or combined with 1,8-cineole, significantly inhibited the transcription of TXNIP and ferroptosis in HG-induced ARPE-19 cells. Conversely, pretreatment with GW9662, a PPAR-γ inhibitor, upregulated the transcription and expression of TXNIP in HG-induced ARPE-19 cells; 1,8-cineole failed to reverse this upregulated expression. To explore these relationships, we constructed a PPAR-γ adenovirus shRNA to elucidate the effect of 1,8-cineole on the negative regulation of TXNIP by PPAR-γ. Taken together, the present findings indicate that HG-induced ferroptosis in retinal tissue plays an essential role in the pathogenesis of DR, which can be ameliorated by 1,8-cineole.

Research progress on the mechanism of ferroptosis and its role in diabetic retinopathy

Ferroptosis is iron-dependent regulatory cell death (RCD). Morphologically, ferroptosis is manifested as mitochondrial atrophy and increased mitochondrial membrane density. Biochemically, ferroptosis is characterized by the depletion of glutathione (GSH), the inactivation of glutathione peroxidase 4 (GPX4), and an increase in lipid peroxides (LPO)and divalent iron ions. Ferroptosis is associated with various diseases, but the relationship with diabetic retinopathy(DR) is less studied. DR is one of the complications of diabetes mellitus and has a severe impact on visual function. The pathology of DR is complex, and the current treatment is unsatisfactory. Therefore, exploring pathogenesis is helpful for the clinical treatment of DR. This paper reviews the pathological mechanism of ferroptosis and DR in recent years and the involvement of ferroptosis in the pathology of DR. In addition, we propose problems that need to be addressed in this research field. It is expected to provide new ideas for treating DR by analyzing the role of ferroptosis in DR.

The mechanisms of NLRP3 inflammasome/pyroptosis activation and their role in diabetic retinopathy

In the working-age population worldwide, diabetic retinopathy (DR), a prevalent complication of diabetes, is the main cause of vision impairment. Chronic low-grade inflammation plays an essential role in DR development. Recently, concerning the pathogenesis of DR, the Nod-Like Receptor Family Pyrin Domain Containing 3 (NLRP3) inflammasome in retinal cells has been determined as a causal factor. In the diabetic eye, the NLRP3 inflammasome is activated by several pathways (such as ROS and ATP). The activation of NPRP3 leads to the secretion of inflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18), and leads to pyroptosis, a rapid inflammatory form of lytic programmed cell death (PCD). Cells that undergo pyroptosis swell and rapture, releasing more inflammatory factors and accelerating DR progression. This review focuses on the mechanisms that activate NLRP3 inflammasome and pyroptosis leading to DR. The present research highlighted some inhibitors of NLRP3/pyroptosis pathways and novel therapeutic measures concerning DR treatment.

Targeting the NLRP3 inflammasome in diabetic retinopathy: From Pathogenesis to Therapeutic Strategies

Diabetic retinopathy (DR) is a common diabetic microvascular complication and the main cause of vision loss in working-aged people. The NLRP3 inflammasome is a cytosolic multimeric complex that plays a significant role in innate immunity. After sensing injury, the NLRP3 inflammasome induces inflammatory mediator secretion and triggers a form of inflammatory cell death known as pyroptosis. Studies over the past five years have shown increased expression of NLRP3 and related inflammatory mediators in vitreous samples from DR patients at different clinical stages. Many NLRP3-targeted inhibitors have shown great antiangiogenic and anti-inflammatory effects in diabetes mellitus models, suggesting that the NLRP3 inflammasome is involved in the progression of DR. This review covers the molecular mechanisms of NLRP3 inflammasome activation. Furthermore, we discuss the implications of the NLRP3 inflammasome in DR, including the induction of pyroptosis and inflammation and the promotion of microangiopathy and retinal neurodegeneration. We also summarize the research progress on targeting the NLRP3 inflammasome in DR therapeutics with the expectation of providing new insights into DR progression and treatment.

Research Progress on Mitochondrial Dysfunction in Diabetic Retinopathy

Diabetic Retinopathy (DR) is one of the most important microvascular complications of diabetes mellitus, which can lead to blindness in severe cases. Mitochondria are energy-producing organelles in eukaryotic cells, which participate in metabolism and signal transduction, and regulate cell growth, differentiation, aging, and death. Metabolic changes of retinal cells and epigenetic changes of mitochondria-related genes under high glucose can lead to mitochondrial dysfunction and induce mitochondrial pathway apoptosis. In addition, mitophagy and mitochondrial dynamics also change adaptively. These mechanisms may be related to the occurrence and progression of DR, and also provide valuable clues for the prevention and treatment of DR. This article reviews the mechanism of DR induced by mitochondrial dysfunction, and the prospects for related treatment.

The Role of the Thioredoxin System in Brain Diseases

The thioredoxin system, consisting of thioredoxin (Trx), thioredoxin reductase (TrxR), and NADPH, plays a fundamental role in the control of antioxidant defenses, cell proliferation, redox states, and apoptosis. Aberrations in the Trx system may lead to increased oxidative stress toxicity and neurodegenerative processes. This study reviews the role of the Trx system in the pathophysiology and treatment of Alzheimer's, Parkinson's and Huntington's diseases, brain stroke, and multiple sclerosis. Trx system plays an important role in the pathophysiology of those disorders via multiple interactions through oxidative stress, apoptotic, neuro-immune, and pro-survival pathways. Multiple aberrations in Trx and TrxR systems related to other redox systems and their multiple reciprocal relationships with the neurodegenerative, neuro-inflammatory, and neuro-oxidative pathways are here analyzed. Genetic and environmental factors (nutrition, metals, and toxins) may impact the function of the Trx system, thereby contributing to neuropsychiatric disease. Aberrations in the Trx and TrxR systems could be a promising drug target to prevent and treat neurodegenerative, neuro-inflammatory, neuro-oxidative stress processes, and related brain disorders.

Thioredoxin-1 regulates IRE1α to ameliorate sepsis-induced NLRP3 inflammasome activation and oxidative stress in Raw 264.7 cell

Sepsis is life-threatening organ dysfunction caused by the dysregulated host response to infection. Endoplasmic reticulum stress (ERS)-mediated inositol-requiring enzyme 1 α (IRE1α) inflammatory signaling pathway is involved in sepsis. NLRP3 inflammasome plays a key role in the activation of caspase-1 and the maturation of IL-1β and IL-18, and finally enhances the inflammatory response. More and more evidences show that ERS is an endogenous trigger of NLRP3 inflammasome. Thioredoxin-1 (Trx-1) is a small ubiquitous thiol-1 protein with redox/inflammation modulatory properties relevant to sepsis pathogenesis. In this study, we investigated the role of Trx-1 in ERS mediated IRE1α/NLRP3 signaling pathway in Raw 264.7 cells. Our results show that Trx-1 reduces the release of inflammatory factors and reactive oxygen species (ROS) by regulating the related proteins in the IRE1α/NLRP3 signaling pathway expression.

Downregulation of Inflammatory Response via Nrf2/Trx1/TXNIP Axis in Oxidative Stress-Induced ARPE-19 Cells and Mouse Model of AMD

Aim

Chronic inflammation is crucial for age-related macular degeneration (AMD) pathogenesis. However, the mechanism involved in activating inflammation remains unclear. This study is aimed at investigating whether nuclear factor erythrocyte-associated factor 2 (Nrf2) negatively regulated the Nod-like receptor protein 3 (NLRP3) inflammasomes through the thioredoxin 1 (Trx1)/thioredoxin interaction protein (TXNIP) complex.

Methods

We determined the optimal hydrogen peroxide (H₂O₂) concentration, time, and changes in reactive oxygen species (ROS) levels. We also constructed animal models using blue LED irradiation. Then, the expression of Nrf2, TXNIP, Trx1, NLRP3, and inflammation-related factors and proteins, along with the changes in retinal thickness and functional status, was analyzed.

Results

The oxidative stress model was established after 1 h intervention with 100 μM H₂O₂. Nrf2 reduced ROS production, protected the ultrastructure of mitochondria, increased the thickness of the ONL layer, and increased the amplitude of a- and b-wave amplitudes in ERG. Trx1 knockdown increased the production of ROS, damaged the ultrastructure of mitochondria, reduced the thickness of the other ONL layer, and reduced the amplitudes of a- and b-waves in the electroretinogram (ERG). Thus, TXNIP in the cytoplasm activated the inflammasomes.

Conclusions

Nrf2 showed antioxidant and anti-inflammatory activity in the H₂O₂-induced cell stress model and blue LED-induced retinal light damage model. TXNIP transferred from the nucleus to the cytoplasm, activated NLRP3, and aggravated the retinal injury in both the cell stress model and the animal blue LED model. In contrast, Trx1 knockout promoted this process. This study revealed the possible role of the thioredoxin system in developing AMD while also providing newer insights for the future treatment of AMD.

Role of Mitochondria in Retinal Pigment Epithelial Aging and Degeneration

Retinal pigment epithelial (RPE) cells form a monolayer between the neuroretina and choroid. It has multiple important functions, including acting as outer blood-retina barrier, maintaining the function of neuroretina and photoreceptors, participating in the visual cycle and regulating retinal immune response. Due to high oxidative stress environment, RPE cells are vulnerable to dysfunction, cellular senescence, and cell death, which underlies RPE aging and age-related diseases, including age-related macular degeneration (AMD). Mitochondria are the powerhouse of cells and a major source of cellular reactive oxygen species (ROS) that contribute to mitochondrial DNA damage, cell death, senescence, and age-related diseases. Mitochondria also undergo dynamic changes including fission/fusion, biogenesis and mitophagy for quality control in response to stresses. The role of mitochondria, especially mitochondrial dynamics, in RPE aging and age-related diseases, is still unclear. In this review, we summarize the current understanding of mitochondrial function, biogenesis and especially dynamics such as morphological changes and mitophagy in RPE aging and age-related RPE diseases, as well as in the biological processes of RPE cellular senescence and cell death. We also discuss the current preclinical and clinical research efforts to prevent or treat RPE degeneration by restoring mitochondrial function and dynamics.

Spotlight on pyroptosis: role in pathogenesis and therapeutic potential of ocular diseases

Pyroptosis is a programmed cell death characterized by swift plasma membrane disruption and subsequent release of cellular contents and pro-inflammatory mediators (cytokines), including IL‐1β and IL‐18. It differs from other types of programmed cell death such as apoptosis, autophagy, necroptosis, ferroptosis, and NETosis in terms of its morphology and mechanism. As a recently discovered form of cell death, pyroptosis has been demonstrated to be involved in the progression of multiple diseases. Recent studies have also suggested that pyroptosis is linked to various ocular diseases. In this review, we systematically summarized and discussed recent scientific discoveries of the involvement of pyroptosis in common ocular diseases, including diabetic retinopathy, age-related macular degeneration, AIDS-related human cytomegalovirus retinitis, glaucoma, dry eye disease, keratitis, uveitis, and cataract. We also organized new and emerging evidence suggesting that pyroptosis signaling pathways may be potential therapeutic targets in ocular diseases, hoping to provide a summary of overall intervention strategies and relevant multi-dimensional evaluations for various ocular diseases, as well as offer valuable ideas for further research and development from the perspective of pyroptosis.

Targeting Novel Regulated Cell Death: Pyroptosis, Necroptosis, and Ferroptosis in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the primary causes of visual impairment in the working-age population. Retinal cell death is recognized as a prominent feature in the pathological changes of DR. Several types of cell death occurrence have been confirmed in DR, which might be the underlying mechanisms of retinal cell loss. Regulated cell death (RCD) originates from too intense or prolonged perturbations of the intracellular or extracellular microenvironment for adaptative responses to cope with stress and restore cellular homeostasis. Pyroptosis, necroptosis, and ferroptosis represent the novel discovered RCD forms, which contribute to retinal cell death in the pathogenesis of DR. This evidence provides new therapeutic targets for DR. In this review, we summarize the mechanisms of three types of RCD and analyse recent advances on the association between novel RCD and DR, aiming to provide new insights into the underlying pathogenic mechanisms and propose a potential new strategy for DR therapy.

Ferroptosis and ferritinophagy in diabetes complications

BACKGROUND

With long-term metabolic malfunction, diabetes can cause serious damage to whole-body tissue and organs, resulting in a variety of complications. Therefore, it is particularly important to further explore the pathogenesis of diabetes complications and develop drugs for prevention and treatment. In recent years, different from apoptosis and necrosis, ferroptosis has been recognized as a new regulatory mode of cell death and involves the regulation of nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy. Evidence shows that ferroptosis and ferritinophagy play a significant role in the occurrence and development of diabetes complications.

SCOPE OF REVIEW

we systematically review the current understanding of ferroptosis and ferritinophagy, focusing on their potential mechanisms, connection, and regulation, discuss their involvement in diabetes complications, and consider emerging therapeutic opportunities and the associated challenges with future prospects.

MAJOR CONCLUSIONS

In summary, ferroptosis and ferritinophagy are worthy targets for the treatment of diabetes complications, but their complete molecular mechanism and pathophysiological process still require further study.

Redox proteome analysis of auranofin exposed ovarian cancer cells (A2780)

The effects of Auranofin (AF) on protein expression and protein oxidation in A2780 cancer cells were investigated through a strategy based on simultaneous expression proteomics and redox proteomics determinations. Bioinformatics analysis of the proteomics data supports the view that the most critical cellular changes elicited by AF treatment consist of thioredoxin reductase inhibition, alteration of the cell redox state, impairment of the mitochondrial functions, metabolic changes associated with conversion to a glycolytic phenotype, induction of ER stress. The occurrence of the above cellular changes was extensively validated by performing direct biochemical assays. Our data are consistent with the concept that AF produces its effects through a multitarget mechanism that mainly affects the redox metabolism and the mitochondrial functions and results into severe ER stress. Results are discussed in the context of the current mechanistic knowledge existing on AF.

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Redox proteomics allows to underline cell adaptation mechanisms in response to Auranofin treatment in ovarian cancer cells.

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BRCA1 is one of the major candidates of the ovarian cancer cell adaptation to Auranofin treatment.

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Auranofin alters the oxidative phosphorylation and mitochondrial protein import machinery.

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TRAP1 C501 modulates Auranofin toxicity.

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Auranofin induces severe stress of the endoplasmic reticulum.

Blue Light Induces RPE Cell Necroptosis, Which Can Be Inhibited by Minocycline

Purpose:

Damage to and death of the retinal pigment epithelium (RPE) are closely related to retinal degeneration. Blue light is a high-energy light that causes RPE damage and triggers inflammatory responses. This study investigates whether blue light induces RPE necroptosis, explores pharmacologic therapy and specific mechanisms, and provides hints for research on retinal degeneration.

Methods

The human RPE cell line ARPE-19 was cultured and subjected to blue light insult in vitro. Annexin V/PI was used to evaluate RPE survival. Minocycline was applied to inhibit the death of RPE. Proteomic measurement was used to analyze protein expression. Inhibitors of necroptosis and apoptosis were applied to assess the death mode. Immunofluorescence of protein markers was detected to analyze the mechanism of cell death. Subcellular structural changes were detected by transmission electron microscopy. Reactive oxygen species (ROS) was tested by DCFH-DA. Mitochondrial membrane potential (Δψ_m) was detected by JC-1. BALB/c mice received bule light exposure, and RPE flatmounts were stained for verification in vivo.

Results

Blue light illumination induced RPE death, and minocycline significantly diminished RPE death. Proteomic measurement showed that minocycline effectively mitigated protein hydrolysis and protein synthesis disorders. Necroptosis inhibitors (Nec-1s, GSK-872) increased the survival of RPE cells, but apoptosis inhibitors (Z-VAD-FMK) did not. After blue light illumination, high-mobility group box-1 (HMGB1) was released from the nucleus, receptor-interacting protein kinase 3 (RIPK3) aggregated, and mixed-lineage kinase domain-like protein (MLKL) increased in the RPE. The application of minocycline alleviated the above phenomena. After blue light illumination, RPE cells exhibited necrotic characteristics accompanied by destruction of cell membranes and vacuole formation, but nuclear membranes remained intact. Minocycline improved the morphology of RPE. Blue light increased ROS and decreased Δψ_m of RPE, minocycline did not reduce ROS but kept Δψ_m stable. In vivo, HMGB1 release and RIPK3 aggregation appeared in the RPE of BALB/c mice after blue light illumination, and minocycline alleviated this effect.

Conclusions

Blue light exposure causes RPE necroptosis. Minocycline reduces the death of RPE by keeping Δψ_m stable, inhibiting necroptosis, and preventing HMGB1 release. These results provide new ideas for the pathogenesis and treatment of retinal degeneration.

A novel miR-338-3p/SLC1A5 axis reprograms retinal pigment epithelium to increases its resistance to high glucose-induced cell ferroptosis

BACKGROUND

Oxidative stress-induced cell ferroptosis occurs during the pathogenesis of diabetic retinopathy (DR), but the detailed molecular mechanisms are still unclear. The present study aimed to investigate this issue.

MATERIALS AND METHODS

The retinal pigment epithelium (RPE) was treated with high glucose (30 mM) in vitro to mimic the realistic conditions of DR progression in vivo. Cell viability was determined by MTT assay and trypan blue staining assay. Gene expressions were examined by Real-Time qPCR and Western Blot analysis. FCM was used to detect cell apoptosis and ROS generation. Dual-luciferase reporter gene system assay was used to verify the targeting sites.

RESULTS

High glucose increased reactive oxygen species (ROS) levels, promoted cell ferroptosis, and suppressed cell proliferation and viability in RPE, which were reversed by co-treating cells with both a ferroptosis inhibitor ferrostatin-1 and an ROS scavenger, N-acetyl-L-Cysteine (NAC). In addition, we screened out a miR-338-3p/ASCT2 (SLC1A5) axis that played an important role in this process. Mechanistically, miR-338-3p targeted the 3' untranslated regions (3'UTR) of SLC1A5 for its inhibition and degradation, and high glucose downregulated SLC1A5 by upregulating miR-338-3p in RPE cells. Next, the miR-338-3p inhibitor and SLC1A5 overexpression vectors were delivered into the RPE cells, and the following gain- and loss-of-function experiments validated that both miR-338-3p ablation and SLC1A5 upregulation abrogated the regulating effects of high glucose on cell proliferation, viability, ferroptosis and ROS production in RPE cells.

CONCLUSIONS

Collectively, data in the present study indicated that targeting the miR-338-3p/SLC1A5 axis could block high glucose-induced ferroptosis in RPE cells.

Astragaloside-IV alleviates high glucose-induced ferroptosis in retinal pigment epithelial cells by disrupting the expression of miR-138-5p/Sirt1/Nrf2

Astragaloside-IV (AS-IV) (C₄₁H₆₈O₁₄) is a high-purity natural product extracted from Astragalus, which has demonstrated biological activities. However, the effect of AS-IV on retinal pigment epithelial (RPE) cells in diabetic retinopathy (DR) remains unclear. In this study, high glucose (HG) was shown to promote ARPE-19 RPE cell death, increase the contents of reactive oxygen species (ROS) and oxidized glutathione (GSSG), and enhance lipid peroxidation density of mitochondrial membrane. In contrast, AS-IV decreased glutathione (GSH) content, mitochondria size and ridge. Addition of iron death inhibitor Ferrostatin-1 (Fer-1) to RPE cells decreased cell dead rate, thus indicating that HG-induced mitochondrial damage occurred due to ferroptosis. AS-IV alleviated HG-induced RPE cell damage. Furthermore, HG decreased levels of silent information regulator 1 (Sirt1) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in the nucleus of RPE cells; AS-IV could alleviate these effects and increased expression of glutathione peroxidase 4 (GPX4), glutamate cysteine ligase (GCLM) and glutamate cysteine ligase catalytic subunit (GCLC), which are Nrf2 downstream genes. Mechanistically, AS-IV was shown to alleviate the effects of HG by increasing mir-138-5p expression in RPE cells and promoting expression of Sirt1 and Nrf2 in the nucleus. Transfection of mir-138-5p agonist inhibited the regulatory effects of AS-IV on Sirt1 and Nrf2, accompanied by decreased GPX4, GCLM and GCLC levels, and restoration of ferroptosis-related changes. Collectively, HG increased ferroptosis rate in RPE cells. In addition, AS-IV inhibited miR-138-5p expression, subsequently increasing Sirt1/Nrf2 activity and cellular antioxidant capacity to alleviate ferroptosis, resulting decreased cell death, which potentially inhibits the DR pathological process.

Thioredoxin upregulation delays diabetes-induced photoreceptor cell degeneration via AMPK-mediated autophagy and exosome secretion

AIMS

Autophagy and exosome secretion in photoreceptor and RPE cells play an important role during diabetic retinopathy (DR). Thioredoxin (Trx) upregulation delays diabetes-induced photoreceptor cell degeneration, which the effect of autophagy and exosome secretion on it is unclear. Therefore, we investigated the effect of them on Trx upregulation to delay diabetes-induced photoreceptor cell degeneration and to identify the potential therapy for DR in the future.

METHODS

Trx-transgenic mice and 661w cell were as models. Retinal function and morphology were evaluated by electroretinography and H&E staining. TUNEL staining was used to evaluate apoptosis. The protein expression was detected by Western blotting. TEM and mRFP-GFP-LC3 method were used to analyze autophagy.

RESULTS

In vitro and in vivo, Trx upregulation can delay diabetes-induced photoreceptor cell degeneration. Moreover, the expression of LC3 and p62 was decreasing and the expression of Alix and CD63 was increasing after Trx overexpression. However, it was inhibited after AMPK inhibitor treatment. Additionally, secreted exosomes from photoreceptor were phagocytosed by RPE cells to regulate its physiological function.

CONCLUSIONS

Trx upregulation can delay diabetes-induced photoreceptor cell degeneration via AMPK-mediated autophagy and exosome secretion. Secreted exosomes from photoreceptor cells could be phagocytosed and degraded by RPE cells in DR.

Novel anti-apoptotic L-DOPA precursors SuperDopa and SuperDopamide as potential neuroprotective agents for halting/delaying progression of Parkinson’s disease

Parkinson’s disease (PD) is characterized by a gradual degeneration of the dopaminergic neurons in the substantia nigra pars compacta (SNpC). Levodopa, the standard PD treatment, provides the missing dopamine in SNpC, but ultimately after a honeymoon with levodopa treatment the neurodegenerative process and the progression of the disease continue. Aimed at prolonging the life of dopaminergic cells, we prepared the levodopa precursors SuperDopa (SD) and SueprDopamide (SDA), in which levodopa is merged with the antioxidant N-acetylcysteine (NAC) into a single molecule. Rotenone is a mitochondrial complex inhibitor often used as experimental model of PD. In vivo, SD and SDA treatment show a significant relief of motor disabilities in rotenone-injected rats. SD and SDA also lower rotenone-induced-α-synuclein (α-syn) expression in human SH-SY5Y cells, and α-syn oligomerization in α-syn-overexpressing-HEK293 cells. In the neuronal SH-SY5Y cells, SD and SDA reverse oxidative stress-induced phosphorylation of cJun-N-terminal kinase (JNK) and p38-mitogen-activated kinase (p38^MAPK). Attenuation of the MAPK-inflammatory/apoptotic pathway in SH-SY5Y cells concurrent with protection of rotenone-triggered motor impairment in rats, is a manifestation of the combined antioxidant/anti-inflammatory activity of SD and SDA together with levodopa release. The concept of joined therapies into a single molecule, where levodopa precursors confer antioxidant activity by enabling NAC delivery across the BBB, provides a potential disease-modifying treatment for slowing PD progression.

Long-Chain Polyunsaturated Fatty Acids and Their Metabolites Regulate Inflammation in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a blinding eye disease, whose incidence strongly increases with ages. The etiology of AMD is complex, including aging, abnormal lipid metabolism, chronic inflammation and oxidative stress. Long-chain polyunsaturated fatty acids (LCPUFA) are essential for ocular structures and functions. This review summarizes the regulatory effects of LCPUFA on inflammation in AMD. LCPUFA are related to aging, autophagy and chronic inflammation. They are metabolized to pro- and anti-inflammatory metabolites by various enzymes. These metabolites stimulate inflammation in response to oxidative stress, causing innate and acquired immune responses. This review also discusses the possible clinical applications, which provided novel targets for the prevention and treatment of AMD and other age-related diseases.

Role of Thioredoxin-1 and its inducers in human health and diseases

Thioredoxin-1 (Trx-1) is a small redox-active protein normally found in mammalian cells that responds to the changing redox environment by contributing electrons or regulating related proteins. There is growing evidence that Trx-1 has multiple functions, including cytoprotective, anti-apoptotic, antioxidant and anti-inflammatory effects. To date, researchers have found that Trx-1 deficiency leads to severe damage in various disease models, such as atherosclerosis, cerebral ischemia, diabetes and tumors. Conversely, activation of Trx-1 has a protective effect against these diseases. Accordingly, a variety of Trx-1 inducers have been widely used in the clinic with significant therapeutic value. In this paper, we summarize the pathogenesis of Trx-1 involvement in the above-mentioned diseases and describe the protective effects of Trx-1 inducers on them.

The advanced glycation end-products (AGEs)/ROS/NLRP3 inflammasome axis contributes to delayed diabetic corneal wound healing and nerve regeneration

Diabetic keratopathy (DK) is an important diabetic complication at the ocular surface. Chronic low-grade inflammation mediated by the NLRP3 inflammasome promotes pathogenesis of diabetes and its complications. However, the effect of the NLRP3 inflammasome on DK pathogenesis remains elusive. Wild-type (WT) and Nlrp3 knockout (KO) C57 mice were used to establish a type I diabetes model by intraperitoneal injection of streptozotocin. The effect of the NLRP3 inflammasome on diabetic corneal wound healing and never regeneration was examined by a corneal epithelial abrasion model. Western blot, immunofluorescence staining, enzyme-linked immunosorbent assay (ELISA) and pharmacological treatment were performed to investigate the regulatory mechanism of advanced glycation end products (AGEs) on NLRP3 inflammasome activation and corneal wound healing in vivo. The cultured mouse corneal epithelial cells (TKE2) were used to evaluate the effect and mechanism of AGEs on NLRP3 inflammasome activation in vitro. We revealed that NLRP3 inflammasome-mediated inflammation and pyroptosis contributed to DK pathogenesis. Under physiological conditions, the NLRP3 inflammasome was required for corneal wound healing and nerve regeneration. However, under a diabetic scenario, sustained activation of the NLRP3 inflammasome resulted in postponed corneal wound healing and impaired nerve regeneration. Mechanistically, the accumulated AGEs promoted hyperactivation of the NLRP3 inflammasome through ROS production. Moreover, genetically and pharmacologically blocking the AGEs/ROS/NLRP3 inflammasome axis significantly expedited diabetic corneal epithelial wound closure and nerve regeneration. Our results revealed that AGEs-induced hyperactivation of the NLRP3 inflammasome resulted in delayed diabetic corneal wound healing and impaired nerve regeneration, which further highlighted the NLRP3 inflammasome as a promising target for DK treatment.

Pyroptosis: A New Insight Into Eye Disease Therapy

Pyroptosis is a lytic form of programmed cell death mediated by gasdermins (GSDMs) with pore-forming activity in response to certain exogenous and endogenous stimuli. The inflammasomes are intracellular multiprotein complexes consisting of pattern recognition receptors, an adaptor protein ASC (apoptosis speck-like protein), and caspase-1 and cause autocatalytic activation of caspase-1, which cleaves gasdermin D (GSDMD), inducing pyroptosis accompanied by cytokine release. In recent years, the pathogenic roles of inflammasomes and pyroptosis in multiple eye diseases, including keratitis, dry eyes, cataracts, glaucoma, uveitis, age-related macular degeneration, and diabetic retinopathy, have been continuously confirmed. Inhibiting inflammasome activation and abnormal pyroptosis in eyes generally attenuates inflammation and benefits prognosis. Therefore, insight into the pathogenesis underlying pyroptosis and inflammasome development in various types of eye diseases may provide new therapeutic strategies for ocular disorders. Inhibitors of pyroptosis, such as NLRP3, caspase-1, and GSDMD inhibitors, have been proven to be effective in many eye diseases. The purpose of this article is to illuminate the mechanism underlying inflammasome activation and pyroptosis and emphasize its crucial role in various ocular disorders. In addition, we review the application of pyroptosis modulators in eye diseases.

Auranofin and ICG-001 Emerge Synergistic Anti-tumor Effect on Canine Breast Cancer by Inducing Apoptosis via Mitochondrial Pathway

Canine breast cancer (CBC) is the most common spontaneous tumor in intact female dogs, especially in developing countries. The effective anti-tumor agents or therapies for the clinical treatment of CBC are still in need. Auranofin (AF) is a gold complex that has been attested by FDA for treating human rheumatism, which has been found as a great anti-tumor agent in recent years. ICG-001 is a small molecule inhibitor of Wnt/β-catenin pathway. In the present study, we demonstrated that a combination of AF and ICG-001 could synergistically suppress the proliferation of CBC in vitro and in vivo. Moreover, the synergistical effect was related with apoptosis caused by mitochondrial damage and ROS production. In conclusion, combination of AF and ICG-001 could synergistically suppress the growth of CBC in vitro and in vivo by leading apoptosis via mitochondrial signaling pathway and might provide a novel potential choice for the clinical treatment of CBC.

Potential Combination Drug Therapy to Prevent Redox Stress and Mitophagy Dysregulation in Retinal Müller Cells under High Glucose Conditions: Implications for Diabetic Retinopathy

Chronic hyperglycemia-induced thioredoxin-interacting protein (TXNIP) expression, associated oxidative/nitrosative stress (ROS/RNS), and mitochondrial dysfunction play critical roles in the etiology of diabetic retinopathy (DR). However, there is no effective drug treatment to prevent or slow down the progression of DR. The purpose of this study is to examine if a combination drug treatment targeting TXNIP and the mitochondria-lysosome pathway prevents high glucose-induced mitochondrial stress and mitophagic flux in retinal Müller glial cells in culture, relevant to DR. We show that diabetes induces TXNIP expression, redox stress, and Müller glia activation (gliosis) in rat retinas when compared to non-diabetic rat retinas. Furthermore, high glucose (HG, 25 mM versus low glucose, LG 5.5 mM) also induces TXNIP expression and mitochondrial stress in a rat retinal Müller cell line, rMC1, in in vitro cultures. Additionally, we develop a mitochondria-targeted mCherry and EGFP probe tagged with two tandem COX8a mitochondrial target sequences (adenovirus-CMV-2×mt8a-CG) to examine mitophagic flux in rMC1. A triple drug combination treatment was applied using TXNIP-IN1 (which inhibits TXNIP interaction with thioredoxin), Mito-Tempo (mitochondrial anti-oxidant), and ML-SA1 (lysosome targeted activator of transient calcium channel MCOLN1/TRPML1 and of transcription factor TFEB) to study the mitochondrial-lysosomal axis dysregulation. We found that HG induces TXNIP expression, redox stress, and mitophagic flux in rMC1 versus LG. Treatment with the triple drug combination prevents mitophagic flux and restores transcription factor TFEB and PGC1α nuclear localization under HG, which is critical for lysosome biosynthesis and mitogenesis, respectively. Our results demonstrate that 2×mt8a-CG is a suitable probe for monitoring mitophagic flux, both in live and fixed cells in in vitro experiments, which may also be applicable to in vivo animal studies, and that the triple drug combination treatment has the potential for preventing retinal injury and disease progression in diabetes.

TNF-α in Uveitis: From Bench to Clinic

Uveitis is an inflammation of the iris, ciliary body, vitreous, retina, or choroid, which has been shown to be the first manifestation of numerous systemic diseases. Studies about the immunopathogenesis and treatment of uveitis are helpful to comprehend systemic autoimmune diseases, and delay the progression of systemic autoimmune diseases, respectively. Tumor necrosis factor-alpha (TNF-α), a pleiotropic cytokine, plays a pivotal role in intraocular inflammation based on experimental and clinical data. Evidence of the feasibility of using anti-TNF-α agents for uveitis management has increased. Although there are numerous studies on TNF-α in various autoimmune diseases, the pathological mechanism and research progress of TNF-α in uveitis have not been reviewed. Therefore, the objective of this review is to provide a background on the role of TNF-α in the immunopathogenesis of uveitis, as well as from bench to clinical research progress, to better guide TNF-α-based therapeutics for uveitis.

The gold complex auranofin: new perspectives for cancer therapy

Advanced stages of cancer are highly associated with short overall survival in patients due to the lack of long-term treatment options following the standard form of care. New options for cancer therapy are needed to improve the survival of cancer patients without disease recurrence. Auranofin is a clinically approved agent against rheumatoid arthritis that is currently enrolled in clinical trials for potential repurposing against cancer. Auranofin mainly targets the anti-oxidative system catalyzed by thioredoxin reductase (TrxR), which protects the cell from oxidative stress and death in the cytoplasm and the mitochondria. TrxR is over-expressed in many cancers as an adaptive mechanism for cancer cell proliferation, rendering it an attractive target for cancer therapy, and auranofin as a potential therapeutic agent for cancer. Inhibiting TrxR dysregulates the intracellular redox state causing increased intracellular reactive oxygen species levels, and stimulates cellular demise. An alternate mechanism of action of auranofin is to mimic proteasomal inhibition by blocking the ubiquitin-proteasome system (UPS), which is critically important in cancer cells to prevent cell death when compared to non-cancer cells, because of its role on cell cycle regulation, protein degradation, gene expression, and DNA repair. This article provides new perspectives on the potential mechanisms used by auranofin alone, in combination with diverse other compounds, or in combination with platinating agents and/or immune checkpoint inhibitors to combat cancer cells, while assessing the feasibility for its repurposing in the clinical setting.

The Antitriple Negative Breast cancer Efficacy of Spatholobus suberectus Dunn on ROS-Induced Noncanonical Inflammasome Pyroptotic Pathway

Breast cancer (BCa) is the leading cause of women's death worldwide; among them, triple-negative breast cancer (TNBC) is one of the most troublesome subtypes with easy recurrence and great aggressive properties. Spatholobus suberectus Dunn has been used in the clinic of Chinese society for hundreds of years. Shreds of evidence showed that Spatholobus suberectus Dunn has a favorable outcome in the management of cancer. However, the anti-TNBC efficacy of Spatholobus suberectus Dunn percolation extract (SSP) and its underlying mechanisms have not been fully elucidated. Hence, the present study is aimed at evaluating the anti-TNBC potential of SSP both in vitro and in vivo, through the cell viability, morphological analysis of MDA-MB-231, LDH release assay, ROS assay, and the tests of GSH aborted pyroptotic noninflammasome signaling pathway. Survival analysis using the KM Plotter and TNM plot database exhibited the inhibition of transcription levels of caspase-4 and 9 related to low relapse-free survival in patients with BCa. Based on the findings, SSP possesses anti-TNBC efficacy that relies on ROS-induced noncanonical inflammasome pyroptosis in cancer cells. In this study, our preclinical evidence is complementary to the preceding clinic of Chinese society; studies on the active principles of SPP remain underway in our laboratory.

Ferrostatin-1 Alleviates White Matter Injury Via Decreasing Ferroptosis Following Spinal Cord Injury

Spinal cord injury (SCI), a devastating neurological impairment, usually imposes a long-term psychological stress and high socioeconomic burden for the sufferers and their family. Recent researchers have paid arousing attention to white matter injury and the underlying mechanism following SCI. Ferroptosis has been revealed to be associated with diverse diseases including stroke, cancer, and kidney degeneration. Ferrostatin-1, a potent inhibitor of ferroptosis, has been illustrated to curb ferroptosis in neurons, subsequently improving functional recovery after traumatic brain injury (TBI) and SCI. However, the role of ferroptosis in white matter injury and the therapeutic effect of ferrostatin-1 on SCI are still unknown. Here, our results indicated that ferroptosis played a pivotal role in the secondary white matter injury, and ferrostatin-1 could reduce iron and reactive oxygen species (ROS) accumulation and downregulate the ferroptosis-related genes and its products of IREB2 and PTGS2 to further inhibit ferroptosis in oligodendrocyte, finally reducing white matter injury and promoting functional recovery following SCI in rats. Meanwhile, the results demonstrated that ferrostatin-1 held the potential of inhibiting the activation of reactive astrocyte and microglia. Mechanically, the present study deciphers the potential mechanism of white matter damage, which enlarges the therapeutic effects of ferrostatin-1 on SCI and even in other central nervous system (CNS) diseases existing ferroptosis.