Exposure to volatile ferroptosis inhibitor, TEMPO, reduced cutaneous ischemia-reperfusion injury progression to pressure ulcer formation in a mouse model

BACKGROUND

Ischemia- reperfusion (I/R) injury-induced oxidative stress is a key factor in the pathogenesis of pressure ulcer formation. Ferroptosis is an iron-dependent programmed cell death that connects oxidative stress and inflammation in various diseases. Recent studies revealed the protective effect of inhibition of ferroptosis in I/R injury. However, the role of ferroptosis in cutaneous I/R injury remains elusive.

OBJECTIVE

To assess the role of ferroptosis in the progression of cutaneous I/R injury.

METHODS

Cutaneous I/R injury experiments and histopathological studies were performed in wild-type mice with or without exposure to volatile ferroptosis inhibitor, TEMPO (2,2,6,6-Tetramethylpiperidine-1-oxyl). The suppressive effects of TEMPO on ferroptosis inducing cell death and oxidative stress were examined in vitro.

RESULTS

Inhibition of ferroptosis with TEMPO significantly reduced ulcer formation after cutaneous I/R injury. Fluctuated ferroptosis markers, such as GPX4, ACSL4, and 4-HNE expression in the I/R skin site, were reversed by TEMPO treatment. Inhibition of ferroptosis reduced apoptosis, CD3+ infiltrating lymphocytes, and improved vascularity in the I/R skin site. Inhibition of ferroptosis also suppressed the enhancement of Nrf2 activation. In vitro, ferroptosis and the activation of ferroptosis-related gene expression by RSL3 stimulation were markedly ameliorated by TEMPO treatment in mouse fibroblasts. Inhibiting ferroptosis also suppressed the elevation of the mRNA levels of NOX2 and HO-1 caused by ferroptosis.

CONCLUSION

Cutaneous I/R injury-induced ferroptosis likely promotes cell death, vascular loss, infiltration of inflammatory cells, and oxidative stress. The inhibition of ferroptosis with TEMPO might have potential clinical application as novel therapeutic agent for cutaneous I/R injury.

Hesperidin Alleviated Intestinal Barrier Injury, Mitochondrial Dysfunction, and Disorder of Endoplasmic Reticulum Mitochondria Contact Sites under Oxidative Stress

As primary flavonoids extracted from citrus fruits, hesperidin has been attracting attention widely for its capacity to act as antioxidants that are able to scavenge free radicals and reactive oxygen species (ROS). Many factors have made oxidative stress a risk factor for the occurrence of intestinal barrier injury, which is a serious health threat to human beings. However, little data are available regarding the underlying mechanism of hesperidin alleviating intestinal injury under oxidative stress. Recently, endoplasmic reticulum (ER) mitochondria contact sites (ERMCSs) have aroused increasing concerns among scholars, which participate in mitochondrial dynamics and Ca2+ transport. In our experiment, 24 piglets were randomly divided into 4 groups. Piglets in the diquat group and hesperidin + diquat group received an intraperitoneal injection of diquat (10 mg/kg), while piglets in the hesperidin group and hesperidin + diquat group received hesperidin (300 mg/kg) with feed. The results indicated that hesperidin alleviated growth restriction and intestinal barrier injury in piglets compared with the diquat group. Hesperidin ameliorated oxidative stress and restored antioxidant capacity under diquat exposure. The mitochondrial dysfunction was markedly alleviated via hesperidin versus diquat group. Meanwhile, hesperidin alleviated ER stress and downregulated the PERK pathway. Furthermore, hesperidin prevented the disorder of ERMCSs by downregulating the level of ERMCS proteins, decreasing the percentage of mitochondria with ERMCSs/total mitochondria and the ratio of ERMCSs length/mitochondrial perimeter. These results suggested hesperidin could alleviate ERMCS disorder and prevent mitochondrial dysfunction, which subsequently decreased ROS production and alleviated intestinal barrier injury of piglets under oxidative stress.

Advances in research on immunocyte iron metabolism, ferroptosis, and their regulatory roles in autoimmune and autoinflammatory diseases

Autoimmune diseases commonly affect various systems, but their etiology and pathogenesis remain unclear. Currently, increasing research has highlighted the role of ferroptosis in immune regulation, with immune cells being a crucial component of the body's immune system. This review provides an overview and discusses the relationship between ferroptosis, programmed cell death in immune cells, and autoimmune diseases. Additionally, it summarizes the role of various key targets of ferroptosis, such as GPX4 and TFR, in immune cell immune responses. Furthermore, the release of multiple molecules, including damage-associated molecular patterns (DAMPs), following cell death by ferroptosis, is examined, as these molecules further influence the differentiation and function of immune cells, thereby affecting the occurrence and progression of autoimmune diseases. Moreover, immune cells secrete immune factors or their metabolites, which also impact the occurrence of ferroptosis in target organs and tissues involved in autoimmune diseases. Iron chelators, chloroquine and its derivatives, antioxidants, chloroquine derivatives, and calreticulin have been demonstrated to be effective in animal studies for certain autoimmune diseases, exerting anti-inflammatory and immunomodulatory effects. Finally, a brief summary and future perspectives on the research of autoimmune diseases are provided, aiming to guide disease treatment strategies.

Optimization of boronic ester-based amphiphilic copolymers for ROS-responsive drug delivery

This study introduces boronic ester-based ROS-responsive amphiphilic copolymers for antioxidant drug delivery. Tuning the hydrophobic/hydrophilic balance optimized the size, curcumin encapsulation, ROS-triggered release, cellular uptake, and intracellular ROS scavenging. The lead P1b formulation self-assembled into stable 10 nm micelles enabling rapid ROS-triggered curcumin release and preferential cellular internalization. P1b eliminated over 90% of pathogenic intracellular ROS within 10 minutes, demonstrating a rapid antioxidant therapy.

Antioxidants and Mechanistic Insights for Managing Dry Age-Related Macular Degeneration

Age-related macular degeneration (AMD) severely affects central vision due to progressive macular degeneration and its staggering prevalence is rising globally, especially in the elderly population above 55 years. Increased oxidative stress with aging is considered an important contributor to AMD pathogenesis despite multifaceted risk factors including genetic predisposition and environmental agents. Wet AMD can be managed with routine intra-vitreal injection of angiogenesis inhibitors, but no satisfactory medicine has been approved for the successful management of the dry form. The toxic carbonyls due to photo-oxidative degradation of accumulated bisretinoids within lysosomes initiate a series of events including protein adduct formation, impaired autophagy flux, complement activation, and chronic inflammation, which is implicated in dry AMD. Therapy based on antioxidants has been extensively studied for its promising effect in reducing the impact of oxidative stress. This paper reviews the dry AMD pathogenesis, delineates the effectiveness of dietary and nutrition supplements in clinical studies, and explores pre-clinical studies of antioxidant molecules, extracts, and formulations with their mechanistic insights.

Iron chelators: as therapeutic agents in diseases

The concentration of iron is tightly regulated, making it an essential element. Various cellular processes in the body rely on iron, such as oxygen sensing, oxygen transport, electron transfer, and DNA synthesis. Iron excess can be toxic because it participates in redox reactions that catalyze the production of reactive oxygen species and elevate oxidative stress. Iron chelators are chemically diverse; they can coordinate six ligands in an octagonal sequence. Because of the ability of chelators to trap essential metals, including iron, they may be involved in diseases caused by oxidative stress, such as infectious diseases, cardiovascular diseases, neurodegenerative diseases, and cancer. Iron-chelating agents, by tightly binding to iron, prohibit it from functioning as a catalyst in redox reactions and transfer iron and excrete it from the body. Thus, the use of iron chelators as therapeutic agents has received increasing attention. This review investigates the function of various iron chelators in treating iron overload in different clinical conditions.

An adaptive drug-releasing contact lens for personalized treatment of ocular infections and injuries

This research introduces an innovative solution to address the challenges of bacterial keratitis and alkali burns. Current treatments for bacterial keratitis and alkali burns rely on the frequent use of antibiotics and anti-inflammatory eye drops. However, these approaches suffer from poor bioavailability and fluctuating concentrations, leading to limited efficacy and potential drug resistance. Our approach presents an adaptive drug-releasing contact lens responsive to reactive oxygen species (ROS) at ocular inflammation sites, synchronously releasing Levofloxacin and Diclofenac. During storage, minimal drug release occurred, but over 7 days of wear, the lens maintained a continuous, customizable drug release rate based on disease severity. This contact lens had strong antibacterial activity and biofilm prevention, effectively treating bacterial keratitis. When combined with autologous serum, this hydrophilic, flexible lens aids corneal epithelial regeneration, reducing irritation and promoting healing. In summary, this ROS-responsive drug-releasing contact lens combines antibacterial and anti-inflammatory effects, offering a promising solution for bacterial keratitis and alkali burns.

Revolutionizing eye care: the game-changing applications of nano-antioxidants in ophthalmology

Since the theory of free radical-induced aging was proposed in 1956, it has been constantly proven that reactive oxygen species (ROS) produced by oxidative stress play a vital role in the occurrence and progression of eye diseases. However, the inherent limitations of traditional drug therapy hindered the development of ophthalmic disease treatment. In recent years, great achievements have been made in the research of nanomedicine, which promotes the rapid development of safe theranostics in ophthalmology. In this review, we focus on the applications of antioxidant nanomedicine in the treatment of ophthalmology. The eye diseases were mainly classified into two categories: ocular surface diseases and posterior eye diseases. In each part, we first introduced the pathology of specific diseases about oxidative stress, and then presented the representative application examples of nano-antioxidants in eye disease therapy. Meanwhile, the nanocarriers that were used, the mechanism of function, and the therapeutic effect were also presented. Finally, we summarized the latest research progress and limitations of antioxidant nanomedicine for eye disease treatment and put forward the prospects of future development.

Potential New Target for Dry Eye Disease-Oxidative Stress

Dry eye disease (DED) is a multifactorial condition affecting the ocular surface. It is characterized by loss of tear film homeostasis and accompanied by ocular symptoms that may potentially result in damage to the ocular surface and even vision loss. Unmodifiable risk factors for DED mainly include aging, hormonal changes, and lifestyle issues such as reduced sleep duration, increased screen exposure, smoking, and ethanol consumption. As its prevalence continues to rise, DED has garnered considerable attention, prompting the exploration of potential new therapeutic targets. Recent studies have found that when the production of ROS exceeds the capacity of the antioxidant defense system on the ocular surface, oxidative stress ensues, leading to cellular apoptosis and further oxidative damage. These events can exacerbate inflammation and cellular stress responses, further increasing ROS levels and promoting a vicious cycle of oxidative stress in DED. Therefore, given the central role of reactive oxygen species in the vicious cycle of inflammation in DED, strategies involving antioxidants have emerged as a novel approach for its treatment. This review aims to enhance our understanding of the intricate relationship between oxidative stress and DED, thereby providing directions to explore innovative therapeutic approaches for this complex ocular disorder.

Bacteria-Targeting Nanoparticles with ROS-Responsive Antibiotic Release to Eradicate Biofilms and Drug-Resistant Bacteria in Endophthalmitis

Background

Bacterial endophthalmitis is an acute progressive visual threatening disease and one of the most important causes of blindness worldwide. Current treatments are unsatisfactory due to the emergence of drug-resistant bacteria and the formation of biofilm.

Purpose

The aim of our research was to construct a novel nano-delivery system with better antimicrobial and antibiofilm effects.

Methods

This study developed a novel antibiotic nanoparticle delivery system (MXF@UiO-UBI-PEGTK), which is composed of (i) moxifloxacin (MXF)-loaded UiO-66 nanoparticle as the core, (ii) bacteria-targeting peptide ubiquicidin (UBI29-41) immobilized on UiO-66, and (iii) ROS-responsive poly (ethylene glycol)-thioketal (PEG-TK) as the surface shell. Then the important properties of the newly developed delivery system, including biocompatibility, toxicity, release percentage, thermal stability, ability of targeting bacteria, and synergistic antibacterial effects on bacterial biofilms and endophthalmitis, were evaluated.

Results

In vitro, MXF@UiO-UBI-PEGTK exhibited significant antibiotic effects including the excellent antibiofilm property against Staphylococcus aureus, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus at high levels of ROS. Moreover, MXF@UiO-UBI-PEGTK demonstrated outstanding efficacy in treating bacterial endophthalmitis in vivo.

Conclusion

This novel nanoparticle delivery system with ROS-responsive and bacteria-targeted properties promotes the precise and effective release of drugs and has significant potential for clinical application of treating bacterial endophthalmitis.

Effect of vincristine on intraocular pressure and tear fluid oxidative stress biomarkers in canine transmissible venereal tumor

BACKGROUND

The ocular side effects of cancer chemotherapeutic drugs are relatively uncommon. Nonetheless, the ocular system has a potentially high sensitivity to toxic substances. This study proposed a framework to assess the effect of vincristine chemotherapy on intraocular pressure, tear protein, and oxidative stress in canines with transmissible venereal tumor (TVT).

METHODS

The study group comprised 10 dogs with TVT, whose diagnosis was based on cytology, and all dogs were treated with vincristine for 4 weeks. Each animal was given a complete ophthalmic examination, followed by a standard Schirmer tear test. Before and 20 min after administering vincristine, intraocular pressure (IOP) was measured in the eyes with a noncontact tonometer. At any of the times mentioned, tear samples were collected using the Schirmer test procedure and were subjected to protein analysis-oxidative stress index (OSI), total antioxidant capacity (TAC), total oxidant status (TOS), nitric oxide (NO), and malondialdehyde (MDA) were determined, and standard statistical analysis was applied.

RESULTS

No significant differences were found in protein in tears, but mean Pre and Postinjection IOP revealed a significant decrease in the eyes each week. Also, results indicated significant differences in oxidative stress markers: increased OSI, NO, and MDA, and reduced TAC.

CONCLUSION

The importance of an increase in oxidative stress levels in the tears of vincristine-treated patients should be taken seriously, as it appears to play a role in the pathogenesis of eye disease. Therefore, during the treatment weeks prior to prescribing vincristine, eye diseases should be evaluated and considered.

Antioxidant potential of chlorogenic acid in Age-Related eye diseases

Oxidative stress is an important mechanism of aging, and in turn, aging can also aggravate oxidative stress, which leads to a vicious cycle. In the process of the brain converting light into visual signals, the eye is stimulated by harmful blue-light radiation directly. Thus, the eye is especially vulnerable to oxidative stress and becomes one of the organs most seriously involved during the aging process. Cataracts, age-related macular degeneration (AMD), glaucoma, diabetic retinopathy (DR), and dry eye are inextricably linked to the aging process and oxidative stress. Chlorogenic acid (CGA) has been demonstrated to have antioxidant and anti-inflammatory activities, and its validity has been established experimentally in numerous fields, including cardiovascular disease, metabolic disorders, cancers, and other chronic diseases. There has previously been evidence of CGA's therapeutic effect in the field of ophthalmopathy. Considering that many ophthalmic drugs lead to systemic side effects, CGA may act as a natural exogenous antioxidant for patients to take regularly, controlling their condition while minimizing side effects. In this paper, in vitro and in vivo studies of CGA in the treatment of age-related eye diseases are reviewed, and the prospects of CGA's antioxidant application for the eye are discussed. The aim of this review is to summarize the relevant knowledge and provide theoretical support for future research.

Study on SH-SY5Y autophagy inhibition and apoptosis induced by methanol extract of Zanthoxylum armatum DC. based on mTOR signal pathway

Background

Zanthoxylum armatum DC. (ZADC) is a novel food raw material resource, offering both edible and medicinal properties. Recent research has unveiled the toxic nature of ZADC, particularly its close association with the nervous system. In a prior study, we observed that administering methanol extract of Zanthoxylum armatum DC. (MZADC) to rats via gavage at a dose of 1.038 g/kg resulted in various neurotoxicity symptoms, including excessive salivation, reduced mobility, unsteady gait, muscle twitching, and altered respiratory rates.

Materials and methods

We conducted cell-based research to assess the safety of ZADC and elucidate its potential toxic mechanism. In addition, we used experimental methods such as Cell Counting Kit-8, Western blot, and Flow cytometry to detect cytotoxicity in SH-SY5Y cells after intervention with MZADC.

Results

Following exposure of SY-SY5Y cells with MZADC, a substantial decline in cell viability was observed, accompanied by a concentration-dependent increase in intracellular reactive oxygen species (ROS) levels. Additionally, MZADC induced cellular oxidative stress, leading to elevated malonic dialdehyde (MDA) and superoxide dismutase (SOD) concentrations while decreasing glutathione (GSH) levels. Furthermore, MZADC induced apoptosis at varying doses (20, 40, and 60 μg/mL), and this effect was associated with increased Caspase-3, Bax expressions, and reduced Bcl2 and Bcl2/Bax expressions. In addition, the investigation revealed that MZADC induced autophagy inhibition in SH-SY5Y cells by activating the mTOR signaling pathway, resulting in a decrease in LC3II/LCI and Beclin-1, while increasing p-mTOR/mTOR, p62.

Conclusion

Consequently, this study suggests that MZADC triggers the mTOR pathway through oxidative stress in SH-SY5Y cells, ultimately leading to apoptosis. Understanding the toxicity mechanisms associated with ZADC can offer a valuable theoretical and experimental basis for its development and utilization.

Neurotoxicity study of ethyl acetate extract of Zanthoxylum armatum DC. on SH-SY5Y based on ROS mediated mitochondrial apoptosis pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Zanthoxylum armatum DC. (ZADC) is a traditional medicinal plant with various pharmacological activities and is widely used in China, Japan, India, and other regions. Previous studies have revealed that the methanol extract of ZADC can cause neurotoxicity symptoms in rats, such as drooling, decreased appetite, decreased movement, and increased respiratory rate. However, the basis of these toxic substances and the mechanism of neurotoxicity remain unclear.

AIM OF THE STUDY

To evaluate the effects of ZADC on nerve cells and their damage mechanisms and discuss the possible toxic substance basis.

MATERIALS AND METHODS

The ethyl acetate extract of ZADC is obtained by extracting the methanol extract of ZADC with ethyl acetate. The Q-Orbitrap LC-MS/MS method was employed to analyze the chemical composition of the EA extract of ZADC. SH-SY5Y cells were incubated with different concentrations of the ethyl acetate extract of ZADC. The cytotoxicity of the extract was evaluated using CCK-8, LDH, and ROS assays, and the oxidative stress status of cells was assessed using MDA, GSH, and SOD. Cell apoptosis was detected using flow cytometry. Damage to mitochondrial function was evaluated by labeling mitochondria, ATP, and MMP with fluorescence. Cyto-C, Caspase-3, Caspase-9, Apaf-1, Bax, and reduced Bcl2 expression were measured to evaluate the activation of the mitochondrial apoptosis pathway. Finally, NAC intervention was used to detect changes in the relevant indicators. The activation of mitochondrial apoptosis pathway was evaluated by measuring Cyto-C, Caspase-3, Caspase-9, Apaf-1, and Bax and Bcl2 expression. Finally, NAC intervention was utilized to detect changes in the relevant indicators.

RESULTS

After treating SY-SY5Y cells with EA extract from ZADC, cell viability decreased significantly, and the intracellular ROS level increased in a dose-dependent manner. Meanwhile, ZADC can cause cellular oxidative stress and increase MDA and SOD concentrations while decreasing GSH concentrations. It can also shorten the mitochondrial cristae and decrease the number of mitochondria. In contrast, it can reduce ATP synthesis in the mitochondria and mitochondrial membrane potential (MMP). Furthermore, it increased the apoptosis rate and the expression of Cyto-C, Caspase-3, Caspase-9, Apaf-1, and Bax and reduced Bcl2 expression. NAC intervention alleviated the reduction in SH-SY5Y cell survival and the accumulation of reactive oxygen species induced by the EA extract in ZADC. It also inhibits signaling pathways dominated by proteins, such as Cyto-C, reducing cell apoptosis and cytotoxicity. A total of 46 compounds were identified in the extracts.

CONCLUSIONS

The results suggest that EA extract of ZADC can induce the mitochondrial apoptotic pathway by accumulating ROS in cells, leading to apoptosis. Antioxidants had a good inhibitory and protective effect against cell damage caused by the EA extract of ZADC. The neurotoxic components of ZADC may be organic acids and compounds containing amino groups.

Body mass index and visual impairment in Israeli adolescents: A nationwide study

BACKGROUND

Previous research on the association between body mass index (BMI) and visual impairment (VI) in youth has reported inconsistent findings. We aimed to investigate this association in a national cohort of Israeli adolescents.

METHODS

This retrospective, population-based, cross-sectional study included 1 697 060 adolescents (56.4% men; mean age 17 years) who underwent mandatory pre-military service assessments from 1993 to 2017. BMI was classified based on the US age- and sex-matched percentiles. Unilateral or bilateral VI was classified as best-corrected visual acuity (BCVA) worse than 6/9 in either or both eyes, respectively. Sex-stratified regression models adjusted for sociodemographic variables were used to analyse the BMI-VI relationship.

RESULTS

Overall, 17 871 (1.05%) and 5148 (0.30%) adolescents had unilateral and bilateral VI, respectively. Compared with high-normal BMI (50th to 85th percentile), adjusted odds ratios (ORs) for unilateral and bilateral VI gradually increased with higher BMI, reaching 1.33 (1.13-1.55) and 1.80 (1.37-2.35) in men with severe obesity, and 1.51 (1.24-1.84) and 1.52 (1.08-2.14) in women with severe obesity, respectively. Men with underweight also had increased ORs for unilateral and bilateral VI (1.23; 1.14-1.33 and 1.59; 1.37-1.84, respectively), a pattern not observed in women (0.96; 0.86-1.07 and 1.02; 0.83-1.25, respectively). Results were maintained when the outcome was restricted to mild VI, as well as in subgroups of adolescents with unimpaired health and those without moderate-to-severe myopia.

CONCLUSIONS

Abnormal BMI, and particularly obesity, is associated with increased OR for VI in late adolescence.

Multifunctional Hydrogel Eye Drops for Synergistic Treatment of Ocular Inflammatory Disease

Uveitis is a complex ocular inflammatory disease with a multifactorial etiology that can result in blindness. Although corticosteroid eye drops are the primary treatment for anterior uveitis, their efficacy is limited by low bioavailability, adverse effects, and a narrow focus on inflammation. In this study, the multifunctional hydrogel eye drops (designated as DCFH) were developed by incorporating the anti-inflammatory agent dexamethasone (DSP) and reactive oxygen species (ROS) scavenger cerium-based metal-organic frameworks (Ce-MOFs) into thermosensitive triblock copolymer F127 for the synergistic treatment against uveitis. The resulting F127 eye drops offer a favorable alternative to ophthalmic solution due to its thermosensitivity, thixotropy, light transmittance, improved ocular bioavailability, and unexpected anti-inflammatory efficacy. Notably, the participation of nanoporous Ce-MOFs, functional drug carriers, not only reduces ROS level but also boosts the anti-inflammatory activity of DSP in vitro. Therapeutically, the multifunctional DCFH exhibits superior efficacy in treating endotoxin-induced uveitis by mitigating the ophthalmic inflammatory reaction, suppressing inflammatory cytokines (e.g., TNF-α, IL-6, and IL-17) and downregulating the expression of iNOS and NLPR3. This synergistic treatment provides a valuable and promising approach for the management of uveitis and other ocular inflammatory conditions.

Lactating buffalos' productive performance, ruminal kinetics, nutrients digestibility and oxidative status as response to supplementing diets with alpinia galanga

The current study investigated the effect of adding different doses of galangal rhizome powder (Alpinia galanga) to the diets of lactating buffaloes on milk production, composition and in vitro ruminal fermentation kinetics. Twenty buffaloes were divided into four groups: (T1) a control diet comprising of concentrates, corn silage and rice straw at 50: 35: 15 on a DM basis, (T2) a control diet plus 15 g of galangal/animal/day and (T3) a control diet plus 30 g of galangal/animal/day and (T4) a control diet plus 45 g of galangal/animal/day. Results showed that inclusion of galangal in diets decreased (p < 0.05) the concentrations of butyrate, ammonia-nitrogen, CO2, and total protozoa count as compared with T1. Acetate concentration was lower in T4 as compared with other groups (p < 0.05). While propionate concentration was lower (p < 0.05) in T2 as compared with T1. T3 and T4 lowered (p < 0.05) methane, CO2 productions, and protozoa count. T3 increased (p < 0.05) milk yield, energy corrected milk (ECM), yield of total solids, total protein, and solids not fat (SNF) than recorded for T1. While T4 recorded the lowest values (p < 0.05) of milk yield, ECM, total solids, fat, and total protein. The current results support the hypothesis that the inclusion of galangal in lactating buffaloes' diets at 30 g per animal daily improved feed intake and milk yield.

Alleviate oxidative stress in diabetic retinopathy: antioxidant therapeutic strategies

OBJECTIVES

This review outlines the function of oxidative stress in DR and discusses therapeutic strategies to treat DR with antioxidants.

METHODS

Published papers on oxidative stress in DR and therapeutic strategies to treat DR with antioxidants were collected and reviewed via database searching on PubMed.

RESULTS

The abnormal development of DR is a complicated process. The pathogenesis of DR has been reported to involve oxidative stress, despite the fact that the mechanisms underlying this are still not fully understood. Excessive reactive oxygen species (ROS) accumulation can damage retina, eventually leading to DR. Increasing evidence have demonstrated that antioxidant therapy can alleviate the degeneration of retinal capillaries in DR.

CONCLUSION

Oxidative stress can play an important contributor in the pathogenesis of DR. Furthermore, animal experiments have shown that antioxidants are a beneficial therapy for treating DR, but more clinical trial data is needed.

Novel Role of Molecular Hydrogen: The End of Ophthalmic Diseases?

Molecular hydrogen (H2) is a colorless, odorless, and tasteless gas which displays non-toxic features at high concentrations. H2 can alleviate oxidative damage, reduce inflammatory reactions and inhibit apoptosis cascades, thereby inducing protective and repairing effects on cells. H2 can be transported into the body in the form of H2 gas, hydrogen-rich water (HRW), hydrogen-rich saline (HRS) or H2 produced by intestinal bacteria. Accumulating evidence suggest that H2 is protective against multiple ophthalmic diseases, including cataracts, dry eye disease, diabetic retinopathy (DR) and other fields. In particular, H2 has been tested in the treatment of dry eye disease and corneal endothelial injury in clinical practice. This medical gas has brought hope to patients suffering from blindness. Although H2 has demonstrated promising therapeutic potentials and broad application prospects, further large-scale studies involving more patients are still needed to determine its optimal application mode and dosage. In this paper, we have reviewed the basic characteristics of H2, and its therapeutic effects in ophthalmic diseases. We also focus on the latest progress in the administration approaches and mechanisms underlying these benefits.

Therapeutic Potential of Antioxidants and Hybrid TEMPOL Derivatives in Ocular Neurodegenerative Diseases: A Glimpse into the Future

Reactive oxygen species play a significant role in the pathogenesis of various ocular neurodegenerative diseases especially glaucoma, age-related macular degeneration (AMD), and ocular ischemic stroke. Increased oxidative stress and the accumulation of ROS have been implicated in the progression of these diseases. As a result, there has been growing interest in exploring potential therapeutic and prophylactic strategies involving exogenous antioxidants. In recent years, there have been significant advancements in the development of synthetic therapeutic antioxidants for targeting reactive oxygen species (ROS) in neurodegenerative diseases. One area of focus has been the development of hybrid TEMPOL derivatives. In the context of ocular diseases, the application of next-generation hybrid TEMPOL antioxidants may offer new avenues for neuroprotection. By targeting ROS and reducing oxidative stress in the retina and optic nerve, these compounds have the potential to preserve retinal ganglion cells and trabecular meshwork and protect against optic nerve damage, mitigating irreversible blindness associated with these diseases. This review seeks to highlight the potential impact of hybrid TEMPOL antioxidants and their derivatives on ocular neurodegenerative disorders.

The Impressive Anti-Inflammatory Activity of Cerium Oxide Nanoparticles: More than Redox?

Cerium oxide nanoparticles (CNPs) are biocompatible nanozymes exerting multifunctional biomimetic activities, including superoxide dismutase (SOD), catalase, glutathione peroxidase, photolyase, and phosphatase. SOD- and catalase-mimesis depend on Ce3+/Ce4+ redox switch on nanoparticle surface, which allows scavenging the most noxious reactive oxygen species in a self-regenerating, energy-free manner. As oxidative stress plays pivotal roles in the pathogenesis of inflammatory disorders, CNPs have recently attracted attention as potential anti-inflammatory agents. A careful survey of the literature reveals that CNPs, alone or as constituents of implants and scaffolds, strongly contrast chronic inflammation (including neurodegenerative and autoimmune diseases, liver steatosis, gastrointestinal disorders), infections, and trauma, thereby ameliorating/restoring organ function. By general consensus, CNPs inhibit inflammation cues while boosting the pro-resolving anti-inflammatory signaling pathways. The mechanism of CNPs' anti-inflammatory effects has hardly been investigated, being rather deductively attributed to CNP-induced ROS scavenging. However, CNPs are multi-functional nanozymes that exert additional bioactivities independent from the Ce3+/Ce4+ redox switch, such as phosphatase activity, which could conceivably mediate some of the anti-inflammatory effects reported, suggesting that CNPs fight inflammation via pleiotropic actions. Since CNP anti-inflammatory activity is potentially a pharmacological breakthrough, it is important to precisely attribute the described effects to one or another of their nanozyme functions, thus achieving therapeutic credibility.

Lactobacillus fermentum HY7302 Improves Dry Eye Symptoms in a Mouse Model of Benzalkonium Chloride-Induced Eye Dysfunction and Human Conjunctiva Epithelial Cells

(1) We investigated the effects of the Lactobacillus fermentum HY7302 (HY7302) in a mouse model of benzalkonium chloride (BAC)-induced dry eye, and the possibility of using HY7302 as a food supplement for preventing dry eye. (2) The ocular surface of Balb/c mice was exposed to 0.2% BAC for 14 days to induce dry eye (n = 8), and the control group was treated with the same amount of saline (n = 8). HY7302 (1 × 10⁹ CFU/kg/day, 14 days, n = 8) was orally administered daily to the mice, and omega-3 (200 mg/kg/day) was used as a positive control. To understand the mechanisms by which HY7302 inhibits BAC-induced dry eye, we performed an in vitro study using a human conjunctival cell line (clone-1-5c-4). (3) The probiotic HY7302 improved the BAC-induced decreases in the corneal fluorescein score and tear break-up time. In addition, the lactic acid bacteria increased tear production and improved the detached epithelium. Moreover, HY7302 lowered the BAC-induced increases in reactive oxygen species production in a conjunctival cell line and regulated the expression of several apoptosis-related factors, including phosphorylated protein kinase B (AKT), B-cell lymphoma protein 2 (Bcl-2), and activated caspase 3. Also, HY7302 alleviated the expression of pro-inflammatory cytokines, such as interleukin-1β (IL-1β), IL-6, and IL-8, and also regulated the matrix metallopeptidase-9 production in the conjunctival cell line. (4) In this study, we showed that L. fermentum HY7302 helps prevent dry eye disease by regulating the expression of pro-inflammatory and apoptotic factors, and could be used as a new functional food composition to prevent dry eye disease.

Elucidating glial responses to products of diabetes-associated systemic dyshomeostasis

Diabetic retinopathy (DR) is a leading cause of blindness in working age adults. DR has non-proliferative stages, characterized in part by retinal neuroinflammation and ischemia, and proliferative stages, characterized by retinal angiogenesis. Several systemic factors, including poor glycemic control, hypertension, and hyperlipidemia, increase the risk of DR progression to vision-threatening stages. Identification of cellular or molecular targets in early DR events could allow more prompt interventions pre-empting DR progression to vision-threatening stages. Glia mediate homeostasis and repair. They contribute to immune surveillance and defense, cytokine and growth factor production and secretion, ion and neurotransmitter balance, neuroprotection, and, potentially, regeneration. Therefore, it is likely that glia orchestrate events throughout the development and progression of retinopathy. Understanding glial responses to products of diabetes-associated systemic dyshomeostasis may reveal novel insights into the pathophysiology of DR and guide the development of novel therapies for this potentially blinding condition. In this article, first, we review normal glial functions and their putative roles in the development of DR. We then describe glial transcriptome alterations in response to systemic circulating factors that are upregulated in patients with diabetes and diabetes-related comorbidities; namely glucose in hyperglycemia, angiotensin II in hypertension, and the free fatty acid palmitic acid in hyperlipidemia. Finally, we discuss potential benefits and challenges associated with studying glia as targets of DR therapeutic interventions. In vitro stimulation of glia with glucose, angiotensin II and palmitic acid suggests that: 1) astrocytes may be more responsive than other glia to these products of systemic dyshomeostasis; 2) the effects of hyperglycemia on glia are likely to be largely osmotic; 3) fatty acid accumulation may compound DR pathophysiology by promoting predominantly proinflammatory and proangiogenic transcriptional alterations of macro and microglia; and 4) cell-targeted therapies may offer safer and more effective avenues for DR treatment as they may circumvent the complication of pleiotropism in retinal cell responses. Although several molecules previously implicated in DR pathophysiology are validated in this review, some less explored molecules emerge as potential therapeutic targets. Whereas much is known regarding glial cell activation, future studies characterizing the role of glia in DR and how their activation is regulated and sustained (independently or as part of retinal cell networks) may help elucidate mechanisms of DR pathogenesis and identify novel drug targets for this blinding disease.

m6A Modification-Association with Oxidative Stress and Implications on Eye Diseases

Oxidative stress (OS) refers to a state of imbalance between oxidation and antioxidation. OS is considered to be an important factor leading to aging and a range of diseases. The eyes are highly oxygen-consuming organs. Due to its continuous exposure to ultraviolet light, the eye is particularly vulnerable to the impact of OS, leading to eye diseases such as corneal disease, cataracts, glaucoma, etc. The N6-methyladenosine (m6A) modification is the most investigated RNA post-transcriptional modification and participates in a variety of cellular biological processes. In this study, we review the role of m6A modification in oxidative stress-induced eye diseases and some therapeutic methods to provide a relatively overall understanding of m6A modification in oxidative stress-related eye diseases.

Distinct Role of Lycium barbarum L. Polysaccharides in Oxidative Stress-Related Ocular Diseases

Oxidative stress is an imbalance between the increased production of reactive species and reduced antioxidant activity, which can cause a variety of disturbances including ocular diseases. Lycium barbarum polysaccharides (LBPs) are complex polysaccharides isolated from the fruit of L. barbarum, showing distinct roles in antioxidants. Moreover, it is relatively safe and non-toxic. In recent years, the antioxidant activities of LBPs have attracted remarkable attention. In order to illustrate its significance and underlying therapeutic value for vision, we comprehensively review the recent progress on the antioxidant mechanisms of LBP and its potential applications in ocular diseases, including diabetic retinopathy, hypertensive neuroretinopathy, age-related macular degeneration, retinitis pigmentosa, retinal ischemia/reperfusion injury, glaucoma, dry eye syndrome, and diabetic cataract.

Ginkgo biloba extracts (GBE) protect human RPE cells from t-BHP-induced oxidative stress and necrosis by activating the Nrf2-mediated antioxidant defence

OBJECTIVES

Age-related macular degeneration (AMD) is a prevalent ocular disease. Dry AMD accounts for most cases of blindness associated with AMD but there are no treatments. Oxidative stress-induced damage to retinal pigment epithelial (RPE) cells is a major contributor to the pathogenesis of dry AMD. This study investigated the protective actions of Ginkgo biloba extracts (GBE) in human RPE cells subjected to tert-butyl hydroperoxide (t-BHP)-mediated oxidative stress.

METHODS

The human ARPE-19 cells were pre-treated with or without GBE before the exposure to t-BHP. Cell viability, cell death profile and lipid peroxidation were assessed. The findings were verified using human primary RPE cultures.

KEY FINDINGS

GBE pre-treatment prevented the increase in lipid peroxidation and necrosis/ferroptosis, and the concurrent viability decrease in RPE cells exposed to t-BHP. It enabled the pronounced activation of Nrf2 and its downstream genes. We found that ERK1/2 phosphorylation was increased to a similar extent by t-BHP and GBE.

CONCLUSION

This study revealed that GBE pre-treatment attenuates pro-oxidant stress and protects human RPE cells from oxidative injury by modulating ERK1/2-Nrf2 axis. These findings suggest that GBE has the potential to be developed as a agent that may be valuable in decreasing AMD progression.

Pterostilbene Confers Protection against Diquat-Induced Intestinal Damage with Potential Regulation of Redox Status and Ferroptosis in Broiler Chickens

Oxidative stress causes damage to macromolecules, including proteins, DNA, and lipid, and has been recognized as a crucial driver of the onset and progression of several intestinal disorders. Pterostilbene, one of the natural antioxidants, has attracted considerable attention owing to its multiple biological activities. In the present study, we established an oxidative stress model in broiler chickens via injection with diquat to investigate whether pterostilbene could attenuate diquat-induced intestinal damage and reveal the underlying mechanisms. We found that diquat-induced decreases in the activities of superoxide dismutase and glutathione peroxidase and the level of reduced glutathione and the increase in hydrogen peroxide content in plasma and jejunum were significantly alleviated by pterostilbene (P < 0.05). Pterostilbene supplementation also decreased intestinal permeability and jejunal apoptosis rate, improved jejunal villus height and the ratio of villus height to crypt depth, and promoted the transcription and translation of jejunal tight junction proteins occludin and zona occludens 1 in diquat-challenged broilers (P < 0.05). Furthermore, pterostilbene reversed diquat-induced mitochondrial injury in the jejunum, as indicated by the decreased reactive oxygen species level and elevated activities of superoxide dismutase 2 and mitochondrial respiratory complexes (P < 0.05). Importantly, administering pterostilbene maintained iron homeostasis, inhibited lipid peroxidation, and regulated the expression of the markers of ferroptosis in the jejunum of diquat-exposed broilers (P < 0.05). The nuclear factor erythroid 2-related factor 2 signaling pathway in the jejunum of diquat-exposed broilers was also activated by pterostilbene (P < 0.05). In conclusion, our study provides evidence that pterostilbene alleviates diquat-induced intestinal mucosa injury and barrier dysfunction by strengthening antioxidant capacity and regulating ferroptosis of broiler chickens.

Oxidative Stress in the Anterior Ocular Diseases: Diagnostic and Treatment

The eye is a metabolically active structure, constantly exposed to solar radiations making its structure vulnerable to the high burden of reactive oxygen species (ROS), presenting many molecular interactions. The biomolecular cascade modification is caused especially in diseases of the ocular surface, cornea, conjunctiva, uvea, and lens. In fact, the injury in the anterior segment of the eye takes its origin from the perturbation of the pro-oxidant/antioxidant balance and leads to increased oxidative damage, especially when the first line of antioxidant defence weakens with age. Furthermore, oxidative stress is related to mitochondrial dysfunction, DNA damage, lipid peroxidation, protein modification, apoptosis, and inflammation, which are involved in anterior ocular disease progression such as dry eye, keratoconus, uveitis, and cataract. The different pathologies are interconnected through various mechanisms such as inflammation, oxidative stress making the diagnostics more relevant in early stages. The end point of the molecular pathway is the release of different antioxidant biomarkers offering the potential of predictive diagnostics of the pathology. In this review, we have analysed the oxidative stress and inflammatory processes in the front of the eye to provide a better understanding of the pathomechanism, the importance of biomarkers for the diagnosis of eye diseases, and the recent treatment of anterior ocular diseases.

A Review on Edible Fungi-Derived Bioactive Peptides: Preparation, Purification and Bioactivities

Edible fungi bioactive peptides (BAPs) are extracted from fruiting bodies and the mycelium of edible fungus. They have various physiological functions such as antioxidant activity, antihypertensive activity, and antibacterial activity. In this paper, the preparation and purification methods of edible fungus BAPs were reviewed, their common biological activities and structure-activity relationships were analyzed, and their application prospects were discussed.

Validity and reliability of food frequency questionnaire used in age-related eye disease studies in Turkish adults

The present study aimed to perform the validity and reliability study of the Food Frequency Questionnaire (FFQ) on the frequency of foods rich in antioxidant nutrients and used in Age-Related Eye Diseases (AREDs). In the first interview of the study, the first application of FFQ was carried out, and blank forms of Dietary Records (DRs) were given. For the validity of the FFQ, a total of 12 d (3 days * 4 weeks) of DR were taken. For the reliability of the FFQ, a test-retest application was made with an interval of 4 weeks. The daily intake means of antioxidant nutrients, omega 3 and total antioxidant capacity data obtained from both the FFQ and DR were calculated, and the concordance between the two methods was evaluated with the Pearson Correlation Coefficient (PCC) and Bland-Altman graphs. The present study was carried out at Ege University İzmir/Turkey, Department of Ophthalmology, Retina Unit. The study was conducted with individuals aged ≥50 years who suffered from Age-Related Macular Degeneration (n 100, 72⋅0 ± 8⋅03 years). The values obtained from the test-retest applications for FFQ reliability were the same. The nutrient intake means obtained from the FFQ were similar or significantly higher than DR (P < 0⋅05). In the Bland-Altman graphical approach, the nutrient data were within the limits of agreement, and the PCCs between the two methods were moderately related. Considered together, this FFQ is a suitable tool for determining the dietary intakes of antioxidant nutrients in the Turkish population.

Genetic Ablation of Nrf2 Exacerbates Neuroinflammation in Ocular Autoimmunity

Experimental autoimmune uveoretinitis (EAU) is an animal model of non-infectious uveitis and is developed by immunization with retinal antigen, interphotoreceptor retinoid-binding protein (IRBP). Nuclear factor erythroid 2- (NF-E2-) related factor 2 (Nrf2) is responsible for regulating antioxidant and inflammatory responses. In this study, we investigated the role of Nrf2 on the development of EAU. Clinical and pathological examination demonstrated that retinal inflammation was exacerbated in Nrf2 knockout (Nrf2 KO) mice compared to wild type (WT) mice, and the expression of inflammatory cytokines (IFN-γ, IL-6, and IL-17) in the retina was significantly elevated in Nrf2 KO mice. GFAP positive cells (astrocytes) and Iba-1 positive cells (microglia cells) in the retina were more numerous in Nrf2 KO mice compared to WT mice. Furthermore, we examined the suppressive effect of the Nrf2 activator CDDO-Im (2-cyano-3,12 dioxooleana-1,9 dien-28-oyl imidazoline) on the development of EAU. The treatment with CDDO-Im significantly reduced the clinical and pathological score of EAU compared to those of vehicle-treated mice. These findings suggest that Nrf2 plays a regulatory role in the pathogenesis of autoimmune uveoretinitis and the activation of the Nrf2 system may have therapeutic potential for protecting vision from autoimmune neuroinflammation.

Oxidative Stress Implication in Retinal Diseases-A Review

Oxidative stress (OS) refers to an imbalance between free radicals (FRs), namely highly reactive molecules normally generated in our body by several pathways, and intrinsic antioxidant capacity. When FR levels overwhelm intrinsic antioxidant defenses, OS occurs, inducing a series of downstream chemical reactions. Both reactive oxygen species (ROS) and reactive nitrogen species (RNS) are produced by numerous chemical reactions that take place in tissues and organs and are then eliminated by antioxidant molecules. In particular, the scientific literature focuses more on ROS participation in the pathogenesis of diseases than on the role played by RNS. By its very nature, the eye is highly exposed to ultraviolet radiation (UVR), which is directly responsible for increased OS. In this review, we aimed to focus on the retinal damage caused by ROS/RNS and the related retinal pathologies. A deeper understanding of the role of oxidative and nitrosative stress in retinal damage is needed in order to develop targeted therapeutic interventions to slow these pathologies.

Mahmoud E, Elansary HO, Sannaningaiah D. Effect of Biofunctional Green Synthesized MgO-Nanoparticles on Oxidative-Stress-Induced Tissue Damage and Thrombosis

The present study describes the green biofunctional synthesis of magnesium oxide (MgO) nanoparticles using the aqueous Tarenna asiatica fruit extract. The characterization of Tarenna asiatica fruit extract MgO nanoparticles (TAFEMgO NPs) was achieved by X-ray powder diffraction, UV-Vis spectroscopy, FTIR, TEM, SEM, and energy-dispersive X-ray diffraction. TAFEMgO NPs scavenged the DPPH free radicals with an IC50 value of 55.95 μg/μL, and it was highly significant compared to the standard. To authenticate the observed antioxidant potential of TAFEMgO NPs, oxidative stress was induced in red blood cells (RBC) using sodium nitrite (NaNO₂). Interestingly, TAFEMgO NPs ameliorated the RBC damage from oxidative stress by significantly restoring the stress parameters, such as the protein carbonyl content (PCC), lipid peroxidation (LPO), total thiol (TT), super-oxide dismutase (SOD), and catalase (CAT). Furthermore, oxidative stress was induced in-vivo in Sprague Dawley female rats using diclofenac (DFC). TAFEMgO NPs normalized the stress parameters in-vivo and minimized the oxidative damage in tissues. Most importantly, TAFEMgO NPs restored the function and architecture of the damaged livers, kidneys, and small intestines by regulating biochemical parameters. TAFEMgO NPs exhibited an anticoagulant effect by increasing the clotting time from 193 s in the control to 885 s in the platelet rich plasma. TAFEMgO NPs prolonged the formation of the clot process in the activated partial thromboplastin time and the prothrombin time, suggest the effective involvement in both intrinsic and extrinsic clotting pathways of the blood coagulation cascade. TAFEMgO NPs inhibited adenosine di-phosphate (ADP)-induced platelet aggregation. TAFEMgO NPs did not show hemolytic, hemorrhagic, and edema-inducing properties at the tested concentration of 100 mg/kgbody weight, suggesting its non-toxic property. In conclusion, TAFEMgO NPs mitigates the sodium nitrite (NaNO₂)- and diclofenac (DFC)-induced stress due to oxidative damage in both in vitro and in vivo experimental models.

Activating transcription factor 2 (AccATF2) regulates tolerance to oxidative stress in Apis cerana cerana

Activating transcription factor 2 (ATF2), a basic leucine zipper (bZIP) transcription factor, plays a crucial role in immune and DNA damage response in mammals. However, the function of ATF2 in insects remains unknown. Here, we isolated the ATF2 gene from Apis cerana cerana (AccATF2) and found that AccATF2 was a main regulator of the honeybee response to oxidative stress. Our results showed that AccATF2 was highly expressed in the head, thorax and integument. AccATF2 was expressed throughout the development period of honeybees, and the highest AccATF2 transcript level was noted in brown-eyed pupae, indicating its indispensable roles in honeybee survival. Antioxidant function analysis showed that AccATF2 expression was markedly induced in response to oxidative stress caused by various environmental stresses. AccATF2 overexpression substantially enhanced the tolerance to oxidative stress of Escherichia coli cells compared with control cells. AccATF2 knockdown significantly increased the production of malondialdehyde (MDA), the transcription of antioxidant genes and the activity of antioxidant enzymes in honeybees, suggesting that AccATF2 knockdown resulted in oxidative damage to honeybees. Moreover, AccATF2 knockdown decreased honeybee resistance to oxidative stress caused by high temperature. Overall, AccATF2 plays an important role in maintaining redox homeostasis and protecting honeybees from oxidative stress caused by various environmental stimuli. Our discoveries add to a growing understanding of how honeybees cope with various adverse environmental conditions to ensure their survival.

Nanoparticles in ocular applications and their potential toxicity

Nanotechnology has been developed rapidly in recent decades and widely applied in ocular disease therapy. Nano-drug delivery systems overcome the bottlenecks of current ophthalmic drug delivery and are characterized with strong biocompatibility, stability, efficiency, sustainability, controllability, and few side effects. Nanoparticles have been identified as a promising and generally safe ophthalmic drug-delivery system based on the toxicity assessment in animals. Previous studies have found that common nanoparticles can be toxic to the cornea, conjunctiva, and retina under certain conditions. Because of the species differences between humans and animals, advanced in vitro cell culture techniques, such as human organoids, can mimic the human organism to a certain extent, bringing nanoparticle toxicity assessment to a new stage. This review summarizes the advanced application of nanoparticles in ocular drug delivery and the potential toxicity, as well as some of the current challenges and future opportunities in nanotoxicological evaluation.

Phytochemical and Safety Evaluations of Finger Lime, Mountain Pepper, and Tamarind in Zebrafish Embryos

Plants play a pivotal role in drug discovery, constituting 50% of modern pharmacopeia. Many human diseases, including age-related degenerative diseases, converge onto common cellular oxidative stress pathways. This provides an opportunity to develop broad treatments to treat a wide range of diseases in the ageing population. Here, we characterize and assess the toxicological effects of finger lime (Citrus australasica), mountain pepper (Tasmannia lanceolata), and small-leaved tamarind (Diploglottis australis) extracts. The characterization demonstrates that these Australian native plants have antioxidant potential and, importantly, they have high concentrations of distinct combinations of different antioxidant classes. Using zebrafish larvae as a high-throughput pre-clinical in vivo toxicology screening model, our experiment effectively discriminates which of these extracts (and at what exposure levels) are suitable for development towards future therapies. The LC50-96h for finger lime and tamarind were >480 mg/L, and 1.70 mg/L for mountain pepper. Critically, this work shows that adverse effects are not correlated to the properties of these antioxidants, thus highlighting the need for combining characterization and in vivo screening to identify the most promising plant extracts for further development. Thus, we present a high-throughput pre-clinical screening that robustly tests natural plant products to utilize the diversity of antioxidant compounds for drug development.

Fisetin Attenuated Oxidative Stress-Induced Cellular Damage in ARPE-19 Human Retinal Pigment Epithelial Cells Through Nrf2-Mediated Activation of Heme Oxygenase-1

Fisetin is a kind of bioactive flavonol, widely present in various fruits such as strawberries and apples, and is known to act as a potent free radical scavenger. However, the mechanism of action related to the antioxidant activity of this compound in human retinal pigment epithelial (RPE) cells is not precisely known. In this study, we aimed to investigate whether fisetin could attenuate oxidative stress-induced cytotoxicity on human RPE ARPE-19 cells. To mimic oxidative stress, ARPE-19 cells were treated with hydrogen peroxide (H₂O₂), and fisetin significantly inhibited H₂O₂-induced loss of cell viability and increase of intracellular reactive oxygen species (ROS) production. Fisetin also markedly attenuated DNA damage and apoptosis in H₂O₂-treated ARPE-19 cells. Moreover, mitochondrial dysfunction in H₂O₂-treated cells was alleviated in the presence of fisetin as indicated by preservation of mitochondrial membrane potential, increase of Bcl-2/Bax expression ratio, and suppression of cytochrome c release into the cytoplasm. In addition, fisetin enhanced phosphorylation and nuclear translocation of nuclear factor erythroid 2 related factor 2 (Nrf2), which was associated with increased expression and activity of heme oxygenase-1 (HO-1). However, the HO-1 inhibitor, zinc protoporphyrin, significantly reversed the protective effect of fisetin against H₂O₂-mediated ARPE-19 cell injury. Therefore, our results suggest that Nrf2-mediated activation of antioxidant enzyme HO-1 may play an important role in the ROS scavenging activity of fisetin in RPE cells, contributing to the amelioration of oxidative stress-induced ocular disorders.

Oxidative stress and visual system: a review

Different types of tissues respond differently to the action of oxidative stress. The visual system is very sensitive to oxidative action due to continuous exposure to light. In consideration of the growing interest of scientific studies towards various compounds endowed with antioxidant and anti-inflammatory properties, we performed a review of the literature focusing on the use of some antioxidant molecules for the treatment of conditions affecting the visual system. In this study, we focused on the ability of two antioxidant agents, the small molecule α-lipoic acid (ALA) and the enzyme superoxide dismutase (SOD), to influence the neurodegenerative physiological processes related to aging and oxidative stress affecting the ocular segment. The literature data report that ALA and SOD can protect against neurodegenerative effects both the optic nerve and retina and, if administered together, they are able to lower the levels of oxidative stress, thus preventing neurodegeneration and reducing the apoptotic process.

Potassium bromate-induced oxidative stress, genotoxicity and cytotoxicity in the blood and liver cells of mice

Potassium bromate (KBrO₃) is an oxidising agent that is extensively used as a food additive, it is also a product of cosmetic and pharmaceutical relevance. The objective of this study was to evaluate the oxidative stress, genotoxicity, and apoptosis induced by KBrO₃ in an experimental animal model. To study the toxic effects and oxidative stress, different doses of KBrO₃ below LD₅₀ (The half maximal lethal dose, 50, 100 and 150 mg/kg body weight) were given intraperitoneally to the mice for multiple time periods (24, 48, and 72 h). The results showed that KBrO₃ significantly induces oxidative damage by increasing the levels of reactive oxygen species (ROS) and lipid peroxidase and depleted the levels of catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH) enzymes in the serum and liver. Moreover, a significant increase of chromosomal aberrations in bone marrow cells and an elevated incidence of micronuclei in the peripheral blood of mice were observed. KBrO₃ induces 3 ´ -OH end double-strand DNA breaks, which was evident in liver sections of the treated mice, and increases the percentage of apoptotic cells, as observed in TUNEL assays and flow cytometry analysis. The present findings indicate that KBrO₃ induces oxidative stress, genotoxicity, and cytotoxicity in a dose- and time-dependent manner in mice.

Cyclophilin A represses reactive oxygen species generation and death of hypoxic non-small-cell lung cancer cells by degrading thioredoxin-interacting protein

Cyclophilin A (cypA) is overexpressed in many types of carcinomas, including non-small-cell lung cancer (NSCLC). However, the effect of anoxia, a critical feature of the carcinoma cell microenvironment, on cypA expression in NSCLC is unknown. Here, formaldehyde-fixed and paraffin-embedded samples were collected from 60 subjects with NSCLC. The protein expression levels of cypA and hypoxia-inducible factor-1α (HIF-1α) were evaluated using immunohistochemistry. Kaplan-Meier analysis showed that subjects with high cypA expression had remarkably shorter progression-free survival than those with low cypA expression. Furthermore, cypA expression levels were significantly related to HIF-1α expression levels (Spearman's correlation=0.34, P<0.0001). To further assess the effect of cypA, an anoxic carcinoma cell model was established. CypA expression was remarkably upregulated in H1299 and A549 cell lines under hypoxic conditions. Overexpression of cypA restored hypoxia-impaired cell growth and prevented reactive oxygen species (ROS) production and cell death in hypoxic A549 and H1299 cells. However, these phenotypes were not altered by the inactive R55A mutant of cypA. Mechanistic studies demonstrated that cypA can bind to and degrade the tumor suppressor protein TXNIP in H1299 and A549 cells. Restored TXNIP expression in cypA-overexpressed and hypoxic NSCLC cells led to increased ROS levels and apoptotic cell numbers and decreased cell growth compared with cypA-overexpressed and hypoxic NSCLC cells. These findings indicate that anoxia results in an increase in cypA expression in NSCLC. Additionally, cypA served as an oncogene during hypoxia by interacting with TXNIP.

Ferroptosis and Apoptosis Are Involved in the Formation of L-Selenomethionine-Induced Ocular Defects in Zebrafish Embryos

Selenium is an essential trace element for humans and other vertebrates, playing an important role in antioxidant defense, neurobiology and reproduction. However, the toxicity of excessive selenium has not been thoroughly evaluated, especially for the visual system of vertebrates. In this study, fertilized zebrafish embryos were treated with 0.5 µM L-selenomethionine to investigate how excessive selenium alters zebrafish eye development. Selenium-stressed zebrafish embryos showed microphthalmia and altered expression of genes required for retinal neurogenesis. Moreover, ectopic proliferation, disrupted mitochondrial morphology, elevated ROS-induced oxidative stress, apoptosis and ferroptosis were observed in selenium-stressed embryos. Two antioxidants—reduced glutathione (GSH) and N-acetylcysteine (NAC)—and the ferroptosis inhibitor ferrostatin (Fer-1) were unable to rescue selenium-induced eye defects, but the ferroptosis and apoptosis activator cisplatin (CDDP) was able to improve microphthalmia and the expression of retina-specific genes in selenium-stressed embryos. In summary, our results reveal that ferroptosis and apoptosis might play a key role in selenium-induced defects of embryonic eye development. The findings not only provide new insights into selenium-induced cellular damage and death, but also important implications for studying the association between excessive selenium and ocular diseases in the future.

Oxidative Stress in the Protection and Injury of the Lacrimal Gland and the Ocular Surface: are There Perspectives for Therapeutics?

Oxidative stress (OS) is a major disruption in the physiology of the lacrimal functional unit (LFU). Antioxidant enzymes have dual protective activities: antioxidant and antimicrobial activities. Peroxidases have been indistinctly used as markers of the secretory activity of the LFU and implicated in the pathophysiology, diagnosis and treatment of dry eye disease (DED), even though they comprise a large family of enzymes that includes lactoperoxidase (LPO) and glutathione peroxidase (GPO), among others. Assays to measure and correlate OS with other local LFU phenomena have methodological limitations. Studies implicate molecules and reactions involved in OS as markers of homeostasis, and other studies identify them as part of the physiopathology of diseases. Despite these conflicting concepts and observations, it is clear that OS is influential in the development of DED. Moreover, many antioxidant strategies have been proposed for its treatment, including calorie restriction to nutritional supplementation. This review offers a critical analysis of the biological mechanisms, diagnostic outcomes, drug use, dietary supplements, and life habits that implicate the influence of OS on DED.

Underutilized Fruit Crops of Indian Arid and Semi-Arid Regions: Importance, Conservation and Utilization Strategies

Nowadays, there is a large demand for nutrient-dense fruits to promote nutritional and metabolic human health. The production of commercial fruit crops is becoming progressively input-dependent to cope with the losses caused by biotic and abiotic stresses. A wide variety of underutilized crops, which are neither commercially cultivated nor traded on a large scale, are mainly grown, commercialized and consumed locally. These underutilized fruits have many advantages in terms of ease to grow, hardiness and resilience to climate changes compared to the major commercially grown crops. In addition, they are exceptionally rich in important phytochemicals and have medicinal value. Hence, their consumption may help to meet the nutritional needs of rural populations, such as those living in fragile arid and semi-arid regions around the world. In addition, local people are well aware of the nutritional and medicinal properties of these crops. Therefore, emphasis must be given to the rigorous study of the conservation and the nutritional characterization of these crops so that the future food basket may be widened for enhancing its functional and nutritional values. In this review, we described the ethnobotany, medicinal and nutritional values, biodiversity conservation and utilization strategies of 19 climate-resilient important, underutilized fruit crops of arid and semi-arid regions (Indian jujube, Indian gooseberry, lasora, bael, kair, karonda, tamarind, wood apple, custard apple, jamun, jharber, mahua, pilu, khejri, mulberry, chironji, manila tamarind, timroo, khirni).

The interplay of autophagy and oxidative stress in the pathogenesis and therapy of retinal degenerative diseases

Oxidative stress is mainly caused by intracellular reactive oxygen species (ROS) production, which is highly associated with normal physiological homeostasis and the pathogenesis of diseases, particularly ocular diseases. Autophagy is a self-clearance pathway that removes oxidized cellular components and regulates cellular ROS levels. ROS can modulate autophagy activity through transcriptional and posttranslational mechanisms. Autophagy further triggers transcription factor activation and degrades impaired organelles and proteins to eliminate excessive ROS in cells. Thus, autophagy may play an antioxidant role in protecting ocular cells from oxidative stress. Nevertheless, excessive autophagy may cause autophagic cell death. In this review, we summarize the mechanisms of interaction between ROS and autophagy and their roles in the pathogenesis of several ocular diseases, including glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR), and optic nerve atrophy, which are major causes of blindness. The autophagy modulators used to treat ocular diseases are further discussed. The findings of the studies reviewed here might shed light on the development and use of autophagy modulators for the future treatment of ocular diseases.

Effects of Daily Melatonin Supplementation on Visual Loss, Circadian Rhythms, and Hepatic Oxidative Damage in a Rodent Model of Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a group of inherited neurodegenerative diseases characterized by a progressive loss of visual function that primarily affect photoreceptors, resulting in the complete disorganization and remodeling of the retina. Progression of the disease is enhanced by increased oxidative stress in the retina, aqueous humor, plasma, and liver of RP animal models and patients. Melatonin has beneficial effects against age-related macular degeneration, glaucoma, and diabetic retinopathy, in which oxidative stress plays a key role. In the present study, we used the P23HxLE rat as an animal model of RP. Melatonin treatment (10 mg/kg b.w. daily in drinking water for 6 months) improved the parameters of visual function and decreased the rate of desynchronization of the circadian rhythm, both in P23HxLE and wild-type rats. Melatonin reduced oxidative stress and increased antioxidant defenses in P23HxLE animals. In wild-type animals, melatonin did not modify any of the oxidative stress markers analyzed and reduced the levels of total antioxidant defenses. Treatment with melatonin improved visual function, circadian synchronization, and hepatic oxidative stress in P23HxLE rats, an RP model, and had beneficial effects against age-related visual damage in wild-type rats.