Therapeutic effect of Keap1-Nrf2-ARE pathway-related drugs on age-related eye diseases through anti-oxidative stress

The role of Keap1-Nrf2 signaling pathway during the progress and therapy of diabetic retinopathy

Diabetic retinopathy is a complex and progressive ocular complication of diabetes mellitus and is a leading cause of blindness in people of working age worldwide. The pathophysiology of diabetic retinopathy involves multifactorial processes, including oxidative stress, inflammation and vascular abnormalities. Understanding the underlying molecular mechanisms involved in its pathogenesis is essential for the development of effective therapeutic interventions. One of the pathways receiving increasing attention is the Keap1-Nrf2 signaling pathway, which regulates the cellular response to oxidative stress by activating Nrf2. In this review, we analyze the current evidence linking Keap1-Nrf2 signaling pathway dysregulation to diabetic retinopathy. In addition, we explore the potential therapeutic implications and the challenges of targeting this pathway for disease management. A comprehensive understanding of the molecular mechanisms of diabetic retinopathy and the therapeutic potential of the Keap1-Nrf2 pathway may pave the way for innovative and effective interventions to combat this vision-threatening disease.

Comparative Study of Hydroxytyrosol Acetate and Hydroxytyrosol in Activating Phase II Enzymes

Nuclear factor E2-related factor 2 (Nrf2) is fundamental to the maintenance of redox homeostasis within cells via the regulation of a series of phase II antioxidant enzymes. The unique olive-derived phenolic compound hydroxytyrosol (HT) is recognized as an Nrf2 activator, but knowledge of the HT derivative hydroxytyrosol acetate (HTac) on Nrf2 activation remains limited. In this study, we observed that an HT pretreatment could protect the cell viability, mitochondrial membrane potential, and redox homeostasis of ARPE-19 cells against a t-butyl hydroperoxide challenge at 50 μM. HTac exhibited similar benefits at 10 μM, indicating a more effective antioxidative capacity compared with HT. HTac consistently and more efficiently activated the expression of Nrf2-regulated phase II enzymes than HT. PI3K/Akt was the key pathway accounting for the beneficial effects of HTac in ARPE-19 cells. A further RNA-Seq analysis revealed that in addition to the consistent upregulation of phase II enzymes, the cells presented distinct expression profiles after HTac and HT treatments. This indicated that HTac could trigger a diverse cellular response despite its similar molecular structure to HT. The evidence in this study suggests that Nrf2 activation is the major cellular activity shared by HTac and HT, and HTac is more efficient at activating the Nrf2 system. This supports its potential future employment in various disease management strategies.

Premature ovarian insufficiency: a review on the role of oxidative stress and the application of antioxidants

Normal levels of reactive oxygen species (ROS) play an important role in regulating follicular growth, angiogenesis and sex hormone synthesis in ovarian tissue. When the balance between ROS and antioxidants is disrupted, however, it can cause serious consequences of oxidative stress (OS), and the quantity and quality of oocytes will decline. Therefore, this review discusses the interrelationship between OS and premature ovarian insufficiency (POI), the potential mechanisms and the methods by which antioxidants can improve POI through controlling the level of OS. We found that OS can mediate changes in genetic materials, signal pathways, transcription factors and ovarian microenvironment, resulting in abnormal apoptosis of ovarian granulosa cells (GCs) and abnormal meiosis as well as decreased mitochondrial Deoxyribonucleic Acid(mtDNA) and other changes, thus accelerating the process of ovarian aging. However, antioxidants, mesenchymal stem cells (MSCs), biological enzymes and other antioxidants can delay the disease process of POI by reducing the ROS level in vivo.

Research progress on the role and mechanism of DNA damage repair in germ cell development

In the complex and dynamic processes of replication, transcription, and translation of DNA molecules, a large number of replication errors or damage can occur which lead to obstacles in the development process of germ cells and result in a decreased reproductive rate. DNA damage repair has attracted widespread attention due to its important role in the maintenance and regulation of germ cells. This study reports on a systematic review of the role and mechanism of DNA damage repair in germline development. First, the causes, detection methods, and repair methods of DNA damage, and the mechanism of DNA damage repair are summarized. Second, a summary of the causes of abnormal DNA damage repair in germ cells is introduced along with common examples, and the relevant effects of germ cell damage. Third, we introduce the application of drugs related to DNA damage repair in the treatment of reproductive diseases and related surgical treatment of abnormal DNA damage, and summarize various applications of DNA damage repair in germ cells. Finally, a summary and discussion is given of the current deficiencies in DNA damage repair during germ cell development and future research development. The purpose of this paper is to provide researchers engaged in relevant fields with a further systematic understanding of the relevant applications of DNA damage repair in germ cells and to gain inspiration from it to provide new research ideas for related fields.

Acteoside inhibits high glucose-induced oxidative stress injury in RPE cells and the outer retina through the Keap1/Nrf2/ARE pathway

Diabetes retinopathy (DR) is one of the most common microvascular complications of diabetes. Retinal pigment epithelial (RPE) cells exposed to a high glucose environment experience a series of functional damages, which is an important factor in promoting the progression of DR. Acteoside (ACT) has strong antioxidant and anti-apoptotic properties, but the mechanism of ACT in DR is not completely clear. Therefore, the purpose of the present study was to explore whether ACT inhibits the damage to RPE cells in a high glucose environment through antioxidative effects to alleviate the DR process. The DR in vitro cell model was constructed by treating RPE cells with high glucose, and the DR in vivo animal model was constructed by injecting streptozotocin (STZ) into the peritoneal cavity of mice to induce diabetes. The proliferation and apoptosis of RPE cells were detected by CCK-8 and flow cytometry assays, respectively. The expression changes in Nrf2, Keap1, NQO1 and HO-1 were evaluated by qRT‒PCR, Western blot and immunohistochemistry analyses. The MDA, SOD, GSH-Px and T-AOC contents were detected by kits. The changes in ROS and nuclear translocation of Nrf2 were observed by immunofluorescence assays. HE staining was used to measure the thickness of the outer nuclear layer (ONL) of the retina, and TUNEL staining was used to detect the number of apoptotic cells in the retinas of mice. In the present study, ACT effectively ameliorated outer retina damage in diabetic mice. In high glucose (HG)-induced RPE cells, ACT treatment had the following effects: improved proliferation, decreased apoptosis, inhibited Keap1 expression, promoted the nuclear translocation and expression of Nrf2, upregulated NQO1 and HO-1 (the target genes of Nrf2) expression, decreased ROS concentration, and increased the levels of the SOD, GSH-Px and T-AOC antioxidant indicators. However, knockdown of Nrf2 reversed the above phenomena, which indicated that the protective function of ACT in HG-induced RPE cells are closely related to Nrf2. In summary, the present study demonstrated that HG-induced oxidative stress injury is inhibited by ACT in RPE cells and the outer retina through the Keap1/Nrf2/ARE pathway.

Co-delivery of microRNA-150 and quercetin by lipid nanoparticles (LNPs) for the targeted treatment of age-related macular degeneration (AMD)

Age-related macular degeneration (AMD) is characterized by choroidal neovascularization (CNV), which leads to severe vision loss in middle-aged and elderly patients. Current treatments for CNV show weak, transient efficacy, and they can cause several adverse effects. A potential new treatment is to use microRNA-150 (mR150), which regulates physiological and pathological angiogenesis by modulating the expression of CXCR4 at the post-transcriptional level. Here, we developed solid lipid nanoparticles that we modified with an Asp-Gly-Arg peptide to target endothelial cells during abnormal angiogenesis, then we co-loaded them with mR150 and the anti-angiogenic drug quercetin. The resulting nanoparticles had an average size around 200 nm and showed strong ability to target the fundus and inhibit CNV for up to two weeks in a mouse model without causing retinal toxicity. They significantly enhanced the uptake of mR150 in vitro compared to free mR150 or nanoparticles without peptide. Our study suggests that co-administration of mR150 and quercetin has potential for treating age-related macular degeneration and that nanoparticles modified with Asp-Gly-Arg peptide are an effective platform for the co-delivery of small-molecule and nucleic acid drugs via intravitreal injection.

Acute Aluminum Sulfate Triggers Inflammation and Oxidative Stress, Inducing Tissue Damage in the Kidney of the Chick

In this study, a total of 20 7-day-old chicks were randomly divided into an experimental group and a control group. The experimental group was administered aluminum sulfate (Al₂(SO₄)₃) once by gavage, and the control group was sacrificed after 24 h of fasting with distilled water. Serum and kidney tissue samples from both groups were collected and compared using hematoxylin-eosin staining (H&E) and microscopy. The Paller scores increased (p < 0.01) for biochemical kidney function, redox-related indicators, and mRNA expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) downstream related genes. The results showed that in the kidneys of the experimental group, renal tubular epithelial cells appeared to swell, and there was necrosis and shedding; the blood urea nitrogen (BUN) and uric acid (UA) decreased, serum creatinine (CREA) increased; nitric oxide (NO), glutathione (GSH), and malondialdehyde (MDA) contents increased; NO synthase (NOS), glutathione peroxidase (GSH-PX), and superoxide dismutase (SOD) enzyme activities increased; tumor necrosis factor alpha (TNF-α), tumor necrosis factor receptor 1 (TNF-R1), tumor necrosis factor receptor 2 (TNF -R2), cyclooxygenase-2 (COX-2), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and heme oxygenase-1 (HO-1) mRNA expression levels increased (p < 0.05 or p < 0.01); Nrf2, glutathione S-transferase A3 (GSTA3), glutathione-S-transferase mu-1 (GSTM1), glutathione synthetase (GSS), glutamate cysteine ligase (GCLC and GCLM), quinone oxidoreductase 1 (NQO1), and Kelch-like ECH-associated protein 1 (Keap1) mRNA expression levels decreased (p < 0.05 or p < 0.01) compared to the control group. Acute aluminum poisoning can cause obvious pathological changes in the structure of the kidney tissue of the chick, resulting in damage to the kidney function, as well as triggering inflammation and oxidative stress in the kidney.

Proteostasis in aging-associated ocular disease

Vision impairment has devastating consequences for the quality of human life. The cells and tissues associated with the visual process must function throughout one's life span and maintain homeostasis despite exposure to a variety of insults. Maintenance of the proteome is termed proteostasis, and is vital for normal cellular functions, especially at an advanced age. Here we describe basic aspects of proteostasis, from protein synthesis and folding to degradation, and discuss the current status of the field with a particular focus on major age-related eye diseases: age-related macular degeneration, cataract, and glaucoma. Our intent is to allow vision scientists to determine where and how to harness the proteostatic machinery for extending functional homeostasis in the aging retina, lens, and trabecular meshwork. Several common themes have emerged despite these tissues having vastly different metabolisms. Continued exposure to insults, including chronic stress with advancing age, increases proteostatic burden and reduces the fidelity of the degradation machineries including the ubiquitin-proteasome and the autophagy-lysosome systems that recognize and remove damaged proteins. This "double jeopardy" results in an exponential accumulation of cytotoxic proteins with advancing age. We conclude with a discussion of the challenges in maintaining an appropriate balance of protein synthesis and degradation pathways, and suggest that harnessing proteostatic capacities should provide new opportunities to design interventions for attenuating age-related eye diseases before they limit sight.

Treatment and prevention of pathological mitochondrial dysfunction in retinal degeneration and in photoreceptor injury

Pathological deterioration of mitochondrial function is increasingly linked with multiple degenerative illnesses as a mediator of a wide range of neurologic and age-related chronic diseases, including those of genetic origin. Several of these diseases are rare, typically defined in the United States as an illness affecting fewer than 200,000 people in the U.S. population, or about one in 1600 individuals. Vision impairment due to mitochondrial dysfunction in the eye is a prominent feature evident in numerous primary mitochondrial diseases and is common to the pathophysiology of many of the familiar ophthalmic disorders, including age-related macular degeneration, diabetic retinopathy, glaucoma and retinopathy of prematurity - a collection of syndromes, diseases and disorders with significant unmet medical needs. Focusing on metabolic mitochondrial pathway mechanisms, including the possible roles of cuproptosis and ferroptosis in retinal mitochondrial dysfunction, we shed light on the potential of α-lipoyl-L-carnitine in treating eye diseases. α-Lipoyl-L-carnitine is a bioavailable mitochondria-targeting lipoic acid prodrug that has shown potential in protecting against retinal degeneration and photoreceptor cell loss in ophthalmic indications.

Acetyl-11-Keto-Beta Boswellic Acid (AKBA) Protects Lens Epithelial Cells Against H2O2-Induced Oxidative Injury and Attenuates Cataract Progression by Activating Keap1/Nrf2/HO-1 Signaling

Age-related cataract (ARC) is one of the leading blinding eye diseases worldwide. Chronic oxidative stress and the apoptosis of human lens epithelial cells (HLECs) have been suggested to be the mechanism underlying cataract formation. Acetyl-11-keto-β-boswellic acid (AKBA) is a pentacyclic triterpene with antioxidative and antiapoptotic effects. In this study, we investigated the potential effects of AKBA on oxidative-induced HLECs injury and cataract formation. H₂O₂ was used to simulate HLECs oxidative injury in vitro, and Na₂SeO₃ was applied to establish an in vivo cataract model. In our current study, a cell counting kit-8 (CCK-8) assay was performed to evaluate the effects of H₂O₂ and AKBA on cell viability in vitro. Intracellular reactive oxygen species (ROS) levels were measured with the ROS assay to verify the antioxidant capacity of AKBA. Apoptotic cells were detected and measured by TUNEL staining and flow cytometry, and quantitative real-time (qRT)-PCR and Western blotting were applied to examine the transcription and expression of apoptosis-related proteins. Furthermore, immunofluorescence staining was performed to locate factor-erythroid 2-related factor 2 (Nrf2), and the protein levels of Nrf2, kelch-like ECH-associated protein 1 (Keap1) and heme oxygenase-1 (HO-1) were determined by Western blotting. Finally, we observed the degree of lens opacity and performed hematoxylin-eosin (H&E) staining to assess the protective effect of AKBA on cataract formation in vivo. AKBA increased HLECs viability under H₂O₂ stimulation, decreased intracellular ROS levels and alleviated the cell apoptosis rate in vitro. AKBA significantly decreased the expression of caspase-3 and Bax and increased the content of Bcl-2. The results of immunofluorescence and immunohistochemical staining proved that the expression and nuclear translocation of Nrf2 were activated with AKBA treatment in vivo and in vitro. Moreover, computational docking results showed that AKBA could bind specifically to the predicted Keap1/Nrf2 binding sites. After AKBA activation, Nrf2 dissociates from the Nrf2/Keap1 complex, translocates into the nucleus, and subsequently promotes HO-1 expression. In addition, AKBA attenuated lens opacity in selenite-induced cataracts. Overall, these findings indicated that AKBA alleviated oxidative injury and cataract formation by activating the Keap1/Nrf2/HO-1 cascade. Therefore, our current study highlights that AKBA may serve as a promising treatment for ARC progression.

Activation of Nrf2/HO-1 Antioxidant Pathway by Heme Attenuates Calcification of Human Lens Epithelial Cells

Cataract, an opacification in the crystalline lens, is a leading cause of blindness. Deposition of hydroxyapatite occurs in a cataractous lens that could be the consequence of osteogenic differentiation of lens epithelial cells (LECs). Nuclear factor erythroid 2-related factor 2 (Nrf2) controls the transcription of a wide range of cytoprotective genes. Nrf2 upregulation attenuates cataract formation. Here we aimed to investigate the effect of Nrf2 system upregulation in LECs calcification. We induced osteogenic differentiation of human LECs (HuLECs) with increased phosphate and calcium-containing osteogenic medium (OM). OM-induced calcium and osteocalcin deposition in HuLECs. We used heme to activate Nrf2, which strongly upregulated the expression of Nrf2 and heme oxygenase-1 (HO-1). Heme-mediated Nrf2 activation was dependent on the production of reactive oxygens species. Heme inhibited Ca deposition, and the OM-induced increase of osteogenic markers, RUNX2, alkaline phosphatase, and OCN. Anti-calcification effect of heme was lost when the transcriptional activity of Nrf2 or the enzyme activity of HO-1 was blocked with pharmacological inhibitors. Among products of HO-1 catalyzed heme degradation iron mimicked the anti-calcification effect of heme. We concluded that heme-induced upregulation of the Nrf2/HO-1 system inhibits HuLECs calcification through the liberation of heme iron.

Based on Activation of p62-Keap1-Nrf2 Pathway, Hesperidin Protects Arsenic-Trioxide-Induced Cardiotoxicity in Mice

Background: Hesperidin (HES) is a flavonoid glycoside found in the tangerine peel and has antioxidant properties. Arsenic trioxide (ATO) is an anti-tumour drug; however, its serious cardiotoxicity limits its clinical application. In addition, the protection of HES against ATO-induced cardiotoxicity has not been explored.

Objective: The study aims to investigate and identify the underlying effect and mechanism of HES on ATO-induced cardiotoxicity.

Methods: Fifty mice were randomly assigned to five groups. Mice were orally given HES:100 or 300 mg/kg/day concurrently and given ATO intraperitoneal injections: 7.5 mg/kg/day for 1 week. Blood and heart tissues were collected for examination. Evaluated in serum was the levels of creatine kinase (CK), lactate dehydrogenase (LDH) and cardiac troponin I (cTnI). In addition, evaluated in heart tissues were the levels of reactive oxygen species (ROS), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), catalase (CAT), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), Caspase-3, cleaved-Caspase-3, p62, Kelch-like ECH-associated protein 1 (Keap1), and nuclear factor erythroid 2-related factor 2 (Nrf2). The heart tissues were also examined for histopathology and mitochondrial ultrastructure.

Results: Compared with the ATO group, the HES treatment groups reduced the levels of CK, LDH, cTnI, ROS, MDA, TNF-α, IL-6, Bax, Caspase-3, cleaved-Caspase-3 and Keap1 and enhanced the levels of SOD, GSH, CAT, Bcl-2, p62 and Nrf2.

Conclusions: The results demonstrate that HES protects against ATO-induced cardiotoxicity, through inhibiting oxidative stress, and subsequent inflammation and apoptosis. The underlying results are closely related to the regulation of the p62-Keap1-Nrf2 signalling pathway.