Protective Effect of Melatonin against Oxidative Stress-Induced Apoptosis and Enhanced Autophagy in Human Retinal Pigment Epithelium Cells

SIRT4 Protects Müller Glial Cells Against Apoptosis by Mediating Mitochondrial Dynamics and Oxidative Stress

SIRT4 is a member of the sirtuin family, which is related to mitochondrial function and possesses antioxidant and regulatory redox effects. Currently, the roles of SIRT4 in retinal Müller glial cells, oxidative stress, and mitochondrial function are still unclear. We confirmed, by immunofluorescence staining, that SIRT4 is located mainly in the mitochondria of retinal Müller glial cells. Using flow cytometry and Western blotting, we analyzed cell apoptosis, intracellular reactive oxygen species (ROS) levels, apoptotic and proapoptotic proteins, mitochondrial dynamics-related proteins, and mitochondrial morphology and number after the overexpression and downregulation of SIRT4 in rMC-1 cells. Neither the upregulation nor the downregulation of SIRT4 alone affected apoptosis. SIRT4 overexpression reduced intracellular ROS, reduced the BAX/BCL2 protein ratio, and increased the L-OPA/S-OPA1 ratio and the levels of the mitochondrial fusion protein MFN2 and the mitochondrial cleavage protein FIS1, increasing mitochondrial fusion. SIRT4 downregulation had the opposite effect. Mitochondria tend to divide after serum starvation for 24 h, and SIRT4 downregulation increases mitochondrial fragmentation and oxidative stress, leading to aggravated cell damage. The mitochondrial division inhibitor Mdivi-1 reduced oxidative stress levels and thus reduced cell damage caused by serum starvation. The overexpression of SIRT4 in rMC-1 cells reduced mitochondrial fragmentation caused by serum starvation, leading to mitochondrial fusion and reduced expression of cleaved caspase-3, thus alleviating the cellular damage caused by oxidative stress. Thus, we speculate that SIRT4 may protect retinal Müller glial cells against apoptosis by mediating mitochondrial dynamics and oxidative stress.

Melatonin: Unveiling the functions and implications in ocular health

Melatonin, a versatile hormone produced by the pineal gland, has garnered considerable scientific interest due to its diverse functions. In the eye, melatonin regulates a variety of key processes like inhibiting angiogenesis by reducing vascular endothelial growth factor levels and protecting the blood-retinal barrier (BRB) integrity by enhancing tight junction proteins and pericyte coverage. Melatonin also maintains cell health by modulating autophagy via the Sirt1/mTOR pathways, reduces inflammation, promotes antioxidant enzyme activity, and regulates intraocular pressure fluctuations. Additionally, melatonin protects retinal ganglion cells by modulating aging and inflammatory pathways. Understanding melatonin's multifaceted functions in ocular health could expand the knowledge of ocular pathogenesis, and shed new light on therapeutic approaches in ocular diseases. In this review, we summarize the current evidence of ocular functions and therapeutic potential of melatonin and describe its roles in angiogenesis, BRB integrity maintenance, and modulation of various eye diseases, which leads to a conclusion that melatonin holds promising treatment potential for a wide range of ocular health conditions.

Temporary alleviation of MAPK by arbutin alleviates oxidative damage in the retina and ARPE-19 cells

Dry age-related macular degeneration (AMD) is one of the main diseases that causes blindness in humans, and the number of cases is increasing yearly. However, effective treatments are unavailable, and arbutin (ARB) has been reported to have antioxidant, anti-inflammatory, and anti-aging effects in other age-related diseases. However, whether ARB can be used to treat dry AMD remains unknown. To explore the therapeutic potential and molecular mechanism of arbutin in the treatment of dry AMD. MTT assays, reactive oxygen species (ROS) production assays, flow cytometry assays, qPCR and western blotting were used to assess the impact of ARB on human RPECs induced by H2O2. A transcriptome sequencing assay was used to further explore how ARB acts on human RPECs treated with H2O2. Hematoxylin and eosin (H&E) staining and total antioxidant capacity (T-AOC) assays were used to observe the impact of ARB on mouse retina induced by sodium iodate. ARB counteracted the H2O2-induced reduction in human RPECs viability, ARB reversed H2O2-induced cellular ROS production by increasing the expression of antioxidant-related genes and proteins, ARB also reversed H2O2-induced cell apoptosis by altering the expression of apoptosis-related genes and proteins. Transcriptome sequencing and western blotting showed that ARB reduced ERK1/2 and P-38 phosphorylation to prevent H2O2-induced oxidation damage. The in vivo experiments demonstrated that ARB protected against retinal morphology injury in mice, increased serum T-AOC levels and increased antioxidant oxidase gene expression levels in the mouse retina induced by sodium iodate. We concluded that ARB reversed the H2O2-induced decrease in human RPECs viability through the inhibition of ROS production and apoptosis. The ERK1/2 and P38 MAPK signaling pathways may mediate this process. ARB maintained retinal morphology, increased serum T-AOC level and improved the expression of antioxidant oxidase genes in mice.

The Role and Therapeutic Potential of Melatonin in Degenerative Fundus Diseases: Diabetes Retinopathy and Age-Related Macular Degeneration

Degenerative fundus disease encompasses a spectrum of ocular diseases, including diabetic retinopathy (DR) and age-related macular degeneration (AMD), which are major contributors to visual impairment and blindness worldwide. The development and implementation of effective strategies for managing and preventing the onset and progression of these diseases are crucial for preserving patients' visual acuity. Melatonin, a neurohormone primarily produced by the pineal gland, exhibits properties such as circadian rhythm modulation, antioxidant activity, anti-inflammatory effects, and neuroprotection within the ocular environment. Furthermore, melatonin has been shown to suppress neovascularization and reduce vascular leakage, both of which are critical in the pathogenesis of degenerative fundus lesions. Consequently, melatonin emerges as a promising therapeutic candidate for degenerative ocular diseases. This review provides a comprehensive overview of melatonin synthesis, its localization within ocular tissues, and its mechanisms of action, particularly in regulating melatonin production, thereby underscoring its potential as a therapeutic agent for degenerative fundus diseases.

Global trends in oxidative stress in the Retina: A bibliometric analysis of 2013-2023

Background

Oxidative stress plays a significant role in the pathogenesis of many retinal diseases. However, only a few systematic bibliometric studies have been conducted. This study aims to visualize research hotspots and developmental trends in oxidative stress in the retina from 2013 to 2023 by analyzing bibliometric data.

Methods

We retrieved papers on oxidative stress in the retina published between 2013 and 2023 from the Web of Science Core Collection. The data were visually analyzed using CiteSpace and VOSviewer software.

Results

The total number of 2100 publications were included in the analysis. An overall increasing trend in the number of publications is observed between 2013 and 2023. Chinese publications were the most contributive, but United States publications were the most influential. Shanghai Jiao Tong University was the most active and prolific institution. Antioxidants was the most productive journal, while Oxidative Medicine and Cellular Longevity were the journals with the most-cited articles. Kaarniranta K, from Finland, was the most productive and influential author. Examination of co-cited references revealed that researchers in the field are primarily focused on investigating the molecular mechanisms, preventive strategies, and utilization of antioxidants to address retinal oxidative damage. Diabetic retinopathy, endothelial growth factor, retinitis pigmentosa, retinal degeneration, antioxidant response, retinal ganglion cells, and genes are the research hotspots in this field. Metabolism, sodium iodate, and system are at the forefront of research in this field.

Conclusion

Attention toward retinal oxidative stress has increased over the past decade. Current research focuses on the mechanisms of retinal diseases related to oxidative stress and the experimental study of antioxidants in retinal diseases, which may continue to be a trend in the future.

Autophagy in dry AMD: A promising therapeutic strategy for retinal pigment epithelial cell damage

Dry age-related macular degeneration (AMD) is a prevalent clinical condition that leads to permanent damage to central vision and poses a significant threat to patients' visual health. Although the pathogenesis of dry AMD remains unclear, there is consensus on the role of retinal pigment epithelium (RPE) damage. Oxidative stress and chronic inflammation are major contributors to RPE cell damage, and the NOD-like receptor thermoprotein structural domain-associated protein 3 (NLRP3) inflammasome mediates the inflammatory response leading to apoptosis in RPE cells. Furthermore, lipofuscin accumulation results in oxidative stress, NLRP3 activation, and the development of vitelliform lesions, a hallmark of dry AMD, all of which may contribute to RPE dysfunction. The process of autophagy, involving the encapsulation, recognition, and transport of accumulated proteins and dead cells to the lysosome for degradation, is recognized as a significant pathway for cellular self-protection and homeostasis maintenance. Recently, RPE cell autophagy has been discovered to be closely linked to the development of macular degeneration, positioning autophagy as a cutting-edge research area in the realm of dry AMD. In this review, we present an overview of how lipofuscin, oxidative stress, and the NLRP3 inflammasome damage the RPE through their respective causal mechanisms. We summarized the connection between autophagy, oxidative stress, and NLRP3 inflammatory cytokines. Our findings suggest that targeting autophagy improves RPE function and sustains visual health, offering new perspectives for understanding the pathogenesis and clinical management of dry AMD.

Melatonin protects photoreceptor cells against ferroptosis in dry AMD disorder by inhibiting GSK-3B/Fyn-dependent Nrf2 nuclear translocation

BACKGROUND

Ferroptosis is a type of non-apoptotic cell death that relies on iron ions and reactive oxygen species to induce lipid peroxidation. This study aimed to determine whether ferroptosis exists in the pathogenesis of dry age-related macular degeneration (AMD) and to confirm that melatonin (MLT) suppresses the photoreceptor cell ferroptosis signaling pathway.

METHODS

We exposed 661W cells to sodium iodate (NaIO3) in vitro and treated them with different concentrations of MLT. In vivo, C57BL/6 mice were given a single caudal vein injection of NaIO3, followed by an intraperitoneal injection of MLT, and eyeballs were taken for subsequent trials.

RESULTS

We found that NaIO3 could induce photoreceptor cell death and lipid peroxide accumulation, and result in changes in the expression of ferroptosis-related factors and iron maintenance proteins, which were treated by MLT. We further demonstrated that MLT can block Fyn-dependent Nrf2 nuclear translocation by suppressing the GSK-3β signaling pathway. In addition, the therapeutic effect of MLT was significantly inhibited when Nrf2 was silenced.

CONCLUSIONS

Our findings provide a novel insight that NaIO3 induces photoreceptor cell ferroptosis in dry AMD and suggest that MLT has therapeutic effects by suppressing GSK-3β/Fyn-dependent Nrf2 nuclear translocation.

Potential Neuroprotective Role of Melatonin in Sepsis-Associated Encephalopathy Due to Its Scavenging and Anti-Oxidative Properties

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. The brain is one of the organs involved in sepsis, and sepsis-induced brain injury manifests as sepsis-associated encephalopathy (SAE). SAE may be present in up to 70% of septic patients. SAE has a very wide spectrum of clinical symptoms, ranging from mild behavioral changes through cognitive disorders to disorders of consciousness and coma. The presence of SAE increases mortality in the population of septic patients and may lead to chronic cognitive dysfunction in sepsis survivors. Therefore, therapeutic interventions with neuroprotective effects in sepsis are needed. Melatonin, a neurohormone responsible for the control of circadian rhythms, exerts many beneficial physiological effects. Its anti-inflammatory and antioxidant properties are well described. It is considered a potential therapeutic factor in sepsis, with positive results from studies on animal models and with encouraging results from the first human clinical trials. With its antioxidant and anti-inflammatory potential, it may also exert a neuroprotective effect in sepsis-associated encephalopathy. The review presents data on melatonin as a potential drug in SAE in the wider context of the pathophysiology of SAE and the specific actions of the pineal neurohormone.

Endogenous and Exogenous Regulation of Redox Homeostasis in Retinal Pigment Epithelium Cells: An Updated Antioxidant Perspective

The retinal pigment epithelium (RPE) performs a range of necessary functions within the neural layers of the retina and helps ensure vision. The regulation of pro-oxidative and antioxidant processes is the basis for maintaining RPE homeostasis and preventing retinal degenerative processes. Long-term stable changes in the redox balance under the influence of endogenous or exogenous factors can lead to oxidative stress (OS) and the development of a number of retinal pathologies associated with RPE dysfunction, and can eventually lead to vision loss. Reparative autophagy, ubiquitin-proteasome utilization, the repair of damaged proteins, and the maintenance of their conformational structure are important interrelated mechanisms of the endogenous defense system that protects against oxidative damage. Antioxidant protection of RPE cells is realized as a result of the activity of specific transcription factors, a large group of enzymes, chaperone proteins, etc., which form many signaling pathways in the RPE and the retina. Here, we discuss the role of the key components of the antioxidant defense system (ADS) in the cellular response of the RPE against OS. Understanding the role and interactions of OS mediators and the components of the ADS contributes to the formation of ideas about the subtle mechanisms in the regulation of RPE cellular functions and prospects for experimental approaches to restore RPE functions.

A small molecule compound that inhibits blue light-induced retinal damage via activation of autophagy

Dry age-related macular degeneration (AMD) is a type of disease that causes visual impairment due to changes in the macula located in the center of the retina. The accumulation of drusen under the retina is also a characteristic of dry AMD. In this study, we identified a compound (JS-017) that can potentially degrade N-retinylidene-N-retinylethanolamine (A2E), one of the components of lipofuscin, using fluorescence-based screening, which measures A2E degradation in human retinal pigment epithelial cells. JS-017 effectively degraded A2E in ARPE-19 cells and consequently suppressed the activation of the NF-κB signaling pathway and expression of inflammatory and apoptosis genes induced by blue light (BL). Mechanistically, JS-017 induced LC3-II formation and improved autophagic flux in ARPE-19 cells. Additionally, the A2E degradation activity of JS-017 was found to be decreased in autophagy-related 5 protein-depleted ARPE-19 cells, suggesting that autophagy was required for A2E degradation mediated by JS-017. Finally, JS-017 exhibited an improvement in BL-induced retinal damage measured through fundus examination in an in vivo retinal degeneration mouse model. The thickness of the outer nuclear layer and inner/external segments, which was decreased upon exposure to BL irradiation, was also restored upon JS-017 treatment. Altogether, we demonstrated that JS-017 protected human retinal pigment epithelium (RPE) cells from A2E and BL-induced damage by degrading A2E via the activation of autophagy. The results suggest the feasibility of a novel A2E-degrading small molecule as a therapeutic agent for retinal degenerative diseases.

High uric acid aggravates apoptosis of lung epithelial cells induced by cigarette smoke extract through downregulating PRDX2 in chronic obstructive pulmonary disease

Cigarette smoke exposure is the major cause of chronic obstructive pulmonary disease (COPD). Cigarette smoke heightens the elevation of reactive oxygen species (ROS) and thus leads to apoptosis. Hyperuricemia has been considered as a risk factor for COPD. However, the underlying mechanism for this aggravating effect remains unclear. The current study sought to examine the role of high uric acid (HUA) in COPD using cigarette smoke extract (CSE) exposed murine lung epithelial (MLE-12) cells. Our data showed that CSE induced the increase of ROS, mitochondrial dynamics disorder, and apoptosis, while HUA treatment aggravated the effects of CSE. Further studies suggested that HUA decreased the expression of antioxidant enzyme-peroxiredoxin-2 (PRDX2). Overexpression of PRDX2 inhibited excessive ROS generation, mitochondrial dynamics disorder, and apoptosis induced by HUA. Knockdown of PRDX2 by small interfering RNA (siRNA) promoted ROS generation, mitochondrial dynamics disorder, and apoptosis in MLE-12 cells treated with HUA. However, antioxidant N-acetylcysteine (NAC) reversed the effects of PRDX2-siRNA on MLE-12 cells. In conclusion, HUA aggravated CSE-induced cellular ROS levels and led to ROS-dependent mitochondrial dynamics disorder and apoptosis in MLE-12 cells through downregulating PRDX2.

Deciphering the Role of Melatonin-Related Signatures in Tumor Immunity and the Prognosis of Clear Cell Renal Cell Carcinoma

Methods

Adopting multiomics data from TCGA and other public datasets, we analysed the expression, mutation, and prognostic evaluation in multiple cancers. ccRCC patients were categorized into two subgroups by an unsupervised cluster algorithm: melatonin-pattern cancer subtype 1 (MPCS1) and subtype 2 (MPCS2). We then explored the immune microenvironment, immune therapy response, and tumor metabolic pathways between the two subtypes. The clinical characteristics, genomic mutation landscape, and molecular inhibitor response were further investigated. Finally, a melatonin regulator-related prognostic model was constructed to predict patient prognosis in ccRCC.

Results

We found that melatonin regulators were dysregulated depending on distinct cancer types, which were associated with genomic variation. The two subtypes indicated different clinical characteristics and biological processes in ccRCC. MPCS2, an aggressive subtype, led an advanced clinical stage and poorer survival of ccRCC patients. The activated oncogenic signaling pathway and metabolic signatures were responsible for cancer progression in the MPCS2 subtype. The MPCS2 subgroup suggested a higher tumor mutational burden and immune dysfunction state, resulting in a lower response to immunotherapy. The copy number variations of MPCS2 were significantly more frequent than those of MPCS1. In addition, the two subgroups exhibited distinct drug responsiveness, with MPCS2 being less responsive to multiple drugs. Finally, we established a subtype biomarker-based prognostic risk model that exhibited satisfactory performance in ccRCC patients.

Conclusion

Melatonin regulator-related features could remodel functional pathways and the tumor immune microenvironment through genomic mutations and pathway regulation. Melatonin regulator-associated molecular subtypes enhance the understanding of the molecular characteristics of renal cancer and can guide clinical treatment. Activating the melatonergic system axis may improve the effect of immunotherapy for ccRCC.

Exploring the Mechanical Perspective of a New Anti-Tumor Agent: Melatonin

Melatonin is a serotonin-derived pineal gland hormone with many biological functions like regulating the sleep-wake cycle, circadian rhythm, menstrual cycle, aging, immunity, and antioxidants. Melatonin synthesis and release are more pronounced during the night, whereas exposure to light decreases it. Evidence is mounting in favor of the therapeutic effects of melatonin in cancer prevention, treatment and delayed onset in various cancer subtypes. Melatonin exerts its anticancer effect through modification of its receptors such as melatonin 1 (MT1), melatonin 2 (MT2), and inhibition of cancer cell proliferation, epigenetic alterations (DNA methylation/demethylation, histone acetylation/deacetylation), metastasis, angiogenesis, altered cellular energetics, and immune evasion. Melatonin performs a significant function in immune modulation and enhances innate and cellular immunity. In addition, melatonin has a remarkable impact on epigenetic modulation of gene expression and alters the transcription of genes. As an adjuvant to cancer therapies, it acts by decreasing the side effects and boosting the therapeutic effects of chemotherapy. Since current treatments produce drug-induced unwanted toxicities and side effects, they require alternate therapies. A recent review article attempts to summarize the mechanistic perspective of melatonin in different cancer subtypes like skin cancer, breast cancer, hepatic cancer, renal cell cancer, non-small cell lung cancer (NSCLC), colon oral, neck, and head cancer. The various studies described in this review will give a firm basis for the future evolution of anticancer drugs.

Neuroprotective effects of melatonin-mediated mitophagy through nucleotide-binding oligomerization domain and leucine-rich repeat-containing protein X1 in neonatal hypoxic-ischemic brain damage

Hypoxia-ischemia (HI) is a major cause of brain damage in neonates. Mitochondrial dysfunction acts as a hub for a broad spectrum of signaling events, culminating in cell death triggered by HI. A neuroprotective role of melatonin (MT) has been proposed, and mitophagy regulation seems to be important for cell survival. However, the molecular mechanisms underlying MT-mediated mitophagy during HI treatment are poorly defined. Nucleotide-binding oligomerization domain and leucine-rich repeat-containing protein X1 (NLRX1) has emerged as a critical regulator of mitochondrial dynamics and neuronal death that participates in the pathology of diverse diseases. This study aimed to clarify whether NLRX1 participates in the regulation of mitophagy during MT treatment for hypoxic-ischemic brain damage (HIBD). We demonstrated that MT protected neonates from HIBD through NLRX1-mediated mitophagy in vitro and in vivo. Meanwhile, MT upregulated the expression of NLRX1, Beclin-1, and autophagy-related 7 (ATG7) but decreased the expression of the mammalian target of rapamycin (mTOR) and translocase of the inner membrane of mitochondrion 23 (TIM23). Moreover, the neuroprotective effects of MT were abolished by silencing NLRX1 after oxygen-glucose deprivation (OGD). In addition, the downregulation of mTOR and upregulation of Beclin-1 and ATG7 by MT were inhibited after silencing NLRX1 under OGD. In summary, MT modulates mitophagy induction through NLRX1 and plays a protective role in HIBD, providing insight into potential therapeutic targets for MT to exert neuroprotection.

FTO inhibits oxidative stress by mediating m6A demethylation of Nrf2 to alleviate cerebral ischemia/reperfusion injury

Current therapies are of limited efficacy in cerebral ischemia/reperfusion (I/R) injury. Based on the important role of oxidative stress in cerebral I/R injury, this study aimed to explore how the N6-adenosine methylation (m6A) demethylase FTO affects oxidative stress. Middle cerebral artery occlusion/reperfusion (MCAO/R)-induced rat model and oxygen and glucose deprivation/re-oxygenation (OGD/R)-induced SH-SY5Y cells were established as in vivo and in vitro model, respectively. The neurological score of rats was measured, and the volume of cerebral infarction was measured by TTC staining. The levels of FTO, nuclear factor-erythroid 2-related factor (Nrf2), and the activity of m6A demethylase FTO were detected. The m6A methylation level of Nrf2 mRNA was detected by MeRIP experiment. Flow cytometry and MTT assay were used to detect apoptosis and proliferation in vitro. TUNEL assay was used to detect apoptosis in brain tissues. FTO and Nrf2 expressions were decreased in the MCAO/R rat brain tissues and OGD/R SH-SY5Y cells, while the m6A methylation level of Nrf2 mRNA was significantly increased. Overexpression of FTO upregulated Nrf2 expression by decreasing the m6A methylation level of Nrf2 mRNA. m6A binding protein YT521-B homology (YTH) domain family protein 2 (YTHDF2) promoted the degradation of Nrf2 by promoting the m6A methylation level of Nrf2 mRNA. Furthermore, SH-SY5Y cell apoptosis was increased and cell viability was decreased after the addition of methyltransferases METTL 3/14, thus blocking FTO to protect SH-SY5Y cells from oxidative stress injury. In vivo, overexpression of FTO decreased the area of cerebral ischemia infarction and the extent of cell apoptosis. In conclusion, FTO increases Nrf2 expression by mediating m6A demethylation of Nrf2 mRNA, thereby inhibiting oxidative stress response and ultimately alleviating cerebral I/R injury.

NLRX1 increases human retinal pigment epithelial autophagy and reduces H2O2-induced oxidative stress and inflammation by suppressing FUNDC1 phosphorylation and NLRP3 activation

BACKGROUND

Age-related macular degeneration (AMD) is a leading cause of impaired vision as well as some earlier effects, such as reading and face recognition. Oxidative damage and inflammation of retinal pigment epithelial (RPE) cells are major causes of AMD. Additionally, autophagy in RPE cells can lead to cellular homeostasis under oxidative stress. Nucleotide-binding oligomerization domain (NOD)-like receptor X1 (NLRX1) is a mysterious modulator of the immune system function which inhibits inflammatory response, attenuates reactive oxygen species (ROS) production, and regulates autophagy. This study attempted to explore the role of NLRX1 in oxidative stress, inflammation, and autophagy in AMD.

METHODS

An in vitro model of AMD was built in human retinal pigment epithelial cell line 19 (ARPE-19) treated with H₂O₂. The cell viability, NLRX1 expressions, levels of superoxide dismutase (SOD), glutathione (GHS), and ROS, concentrations of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, and monocyte chemoattractant protein-1 (MCP-1), expressions of NLRX1, p62, LC3-II/LC3-I, FUNDC1, and NOD-like receptor protein 3 (NLRP3) inflammasome were expounded by cell counting kit-8, colorimetric, enzyme-linked immunosorbent serologic assay (ELISA), and Western blot assay.

RESULTS

H₂O₂ treatment notably reduced the relative protein expression of NLRX1. Meanwhile, H₂O₂ incubation decreased cell viability, diminished SOD and GSH concentrations, accompanied with the increased level of ROS, enhanced IL-1β, TNF-α, IL-6, and MCP-1 concentrations, and aggrandized the relative protein expression of p62 with reduced LC3-II/LC3-I ratio. Moreover, these results were further promoted with knockdown of NLRX1 and reversed with overexpression. Mechanically, silencing of NLRX1 further observably enhanced the relative levels of -phosphorylated FUNDC1/FUNDC1, and NLRP3 inflammasome-related proteins, while overexpression of NLRX1 exhibited inverse results in the H₂O₂-induced ARPE-19 cells.

CONCLUSION

NLRX1 suppressed H₂O₂-induced oxidative stress and inflammation, and facilitated autophagy by suppressing FUNDC1 phosphorylation and NLRP3 activation in ARPE-19 cells.

Melatonin inhibits ferroptosis and delays age-related cataract by regulating SIRT6/p-Nrf2/GPX4 and SIRT6/NCOA4/FTH1 pathways

BACKGROUND

Cataracts are the main cause of reversible blindness worldwide. The ageing of the lens caused by ultraviolet B (UVB) radiation is mostly related to oxidative stress (OS). Little is known about whether OS induced by UVB enhances the sensitivity of lens epithelial cells to ferroptotic stress, which may be a new mechanism leading to age-related cataracts (ARCs).

METHODS

Ferroptosis was detected by transmission electron microscopy (TEM), iron assay, lipid peroxidation (MDA) assay, real-time PCR, western blotting, and immunofluorescence. Genetic engineering technology was used to investigate the regulatory relationship among Sirtuin 6 (SIRT6), nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear receptor coactivator 4 (NCOA4), glutathione peroxidase 4 (GPX4) and ferritin heavy chain (FTH1). Knockdown and overexpression of SIRT6 locally in vivo in rats were performed to probe the regulatory mechanism of SIRT6 in ferroptosis in ARCs.

FINDINGS

Here, we observed that UVB can drastically induce ferroptosis in lens epithelial cells in vivo and in vitro. Surprisingly, inhibition of ferroptosis was the direct reason that melatonin rescued B-3, SRA01/04 and HEK-293 T cells survival; the pan-caspase inhibitor Z-Vad-FMK did not significantly reverse the death of UVB-irradiated cells compared with that in the UVB+DMSO group. SIRT6 was an upstream regulator of phosphorylated Nrf2 (p-Nrf2) and NCOA4 in B-3, SRA01/04 and HEK-293 T cells. Melatonin inhibited ferroptosis through the SIRT6/p-Nrf2/GPX4 and SIRT6/COA4/FTH1 pathways to neutralize lipid peroxidation toxicity, which protected cells against ferroptotic stress in vitro and delayed cataract formation caused by UVB exposure in rats.

INTERPRETATION

Our findings reveal a novel causal role of melatonin in the pathogenesis of ARCs, which raises the possibility of selectively targeting the activation of SIRT6 and ferroptotic resistance as a latent antioxidative therapeutic strategy for ARCs.

Extraction and Purification of Flavonoids from Buddleja officinalis Maxim and Their Attenuation of H2O2-Induced Cell Injury by Modulating Oxidative Stress and Autophagy

Cataracts are an ailment representing the leading cause of blindness in the world. The pathogenesis of cataracts is not clear, and there is no effective treatment. An increasing amount of evidence shows that oxidative stress and autophagy in lens epithelial cells play a key role in the occurrence and development of cataracts. Buddleja officinalis Maxim flavonoids (BMF) are natural antioxidants and regulators that present anti-inflammatory and anti-tumor effects, among others. In this study, we optimized the extraction method of BMFs and detected three of their main active monomers (luteolin, apigenin, and acacetin). In addition, a model of oxidative damage model using rabbit lens epithelial cells induced by hydrogen peroxide (H2O2). By detecting the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), and OH (OH), the expression of autophagosomes and autolysosomes were observed after MRFP-GFP-LC3 adenovirus was introduced into the cells. Western blotting was used to detect the expression of Beclin-1 and P62. Our research results showed that the optimal extraction parameters to obtain the highest yield of total flavonoids were a liquid−solid ratio of 1:31 g/mL, an ethanol volume fraction of 67%, an extraction time of 2.6 h, and an extraction temperature of 58 °C. Moreover, the content of luteolin was 690.85 ppb, that of apigenin was 114.91 ppb, and the content of acacetin was 5.617 ppb. After oxidative damage was induced by H2O2, the cell survival rate decreased significantly. BMFs could increase the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decrease the levels of malondialdehyde (MDA) and OH (OH). After the MRFP-GFP-LC3 virus was introduced into rabbit lens epithelial cells and detecting the expression of P62 and Beclin-1, we found that the intervention of BMF could promote the binding of autophagosomes to lysosomes. Compared with the model group, the level of P62 in the low-, middle-, and high-dose groups of BMF was significantly down-regulated, the level of Beclin-1 was significantly increased, and the difference was statistically significant (p < 0.05). In other words, the optimized extraction method was better than others, and the purified BMF contained three main active monomers (luteolin, apigenin, and acacetin). In addition, BMFs could ameliorate the H2O2-induced oxidative damage to rabbit lens cells by promoting autophagy and regulating the level of antioxidation.

The Berberis vulgaris L. extract berberine exerts its anti-oxidant effects to ameliorate cholesterol overloading-induced cell apoptosis in the primary mice hepatocytes: an in vitro study

Cholesterol overloading stress damages normal cellular functions in hepatocytes and induces metabolic disorders to facilitate the development of multiple diseases, including cardiovascular diseases, which seriously degrades the life quality of human beings. Recent data suggest that the Berberis vulgaris L. extract berberine is capable of regulating cholesterol homeostasis, which is deemed as potential therapeutic drug for the treatment of cholesterol overloading-associated diseases, but its detailed functions and molecular mechanisms are still largely unknown. In the present study, we evidenced that berberine suppressed cell apoptosis in high-cholesterol-diet mice liver and cholesterol-overloaded mice hepatocytes. Also, cholesterol overloading promoted reactive oxygen species (ROS) generation to trigger oxidative damages in hepatocytes, which were reversed by co-treating cells with both berberine and the ROS scavenger N-acetylcysteine (NAC). Moreover, the underlying mechanisms were uncovered, and we validated that berberine downregulated Keap1, and upregulated Nrf2 to activate the anti-oxidant Nrf2/HO-1 signaling pathway in cholesterol overloading-treated hepatocytes, and both Keap1 upregulation and Nrf2 downregulation abrogated the suppressing effects of berberine on cell apoptosis in the hepatocytes with cholesterol exposure. Taken together, we concluded that berberine activated the anti-oxidant Keap1/Nrf2/HO-1 pathway to eliminate cholesterol overloading-induced oxidative stress and apoptotic cell death in mice hepatocytes, and those evidences hinted that berberine might be used as putative therapeutic drug for the treatment of cholesterol overloading-associated cardiovascular diseases.

Phloroglucinol Attenuates DNA Damage and Apoptosis Induced by Oxidative Stress in Human Retinal Pigment Epithelium ARPE-19 Cells by Blocking the Production of Mitochondrial ROS

Phloroglucinol, a phenolic compound, is known to possess a potent antioxidant ability. However, its role in retinal cells susceptible to oxidative stress has not been well elucidated yet. Thus, the objective of this study was to evaluate whether phloroglucinol could protect against oxidative damage in cultured human retinal pigment epithelium ARPE-19 cells. For this purpose, ARPE-19 cells were stimula ted with hydrogen peroxide (H₂O₂) to mimic oxidative stress. Cell viability, cytotoxicity, apoptosis, reactive oxygen species (ROS) generation, mitochondrial function, DNA damage, and autophagy were then assessed. Our results revealed that phloroglucinol ameliorated cell viability, cytotoxicity, and DNA damage in H₂O₂-exposued ARPE-19 cells and blocked production of ROS. Phloroglucinol also counteracted H₂O₂-induced apoptosis by reducing Bax/Bcl-2 ratio, blocking activation of caspase-3, and inhibiting degradation of poly (ADP-ribose) polymerase. H₂O₂ caused mitochondrial impairment and increased expression levels of mitophagy markers such as PINK1and PARKIN known to be associated with mitochondrial ROS (mtROS) generation and cytosolic release of cytochrome c. However, these changes were significantly attenuated by phloroglucinol. Mito-TEMPO, a selective mitochondrial antioxidant, further enhanced the protective effect of phloroglucinol against dysfunctional mitochondria. Furthermore, H₂O₂ induced autophagy, but not when ARPE-19 cells were pretreated with phloroglucinol, meaning that autophagy by H₂O₂ contributed to the pro-survival mechanism and that phloroglucinol protected ARPE-19 cells from apoptosis by blocking autophagy. Taken together, these results suggest that phloroglucinol can inhibit oxidative stress-induced ARPE-19 cell damage and dysfunction by protecting DNA damage, autophagy, and subsequent apoptosis through mitigation of mtROS generation. Thus, phloroglucinol might have therapeutic potential to prevent oxidative stress-mediated damage in RPE cells.

Intestinal microbiota and melatonin in the treatment of secondary injury and complications after spinal cord injury

Spinal cord injury (SCI) is a central nervous system (CNS) disease that can cause sensory and motor impairment below the level of injury. Currently, the treatment scheme for SCI mainly focuses on secondary injury and complications. Recent studies have shown that SCI leads to an imbalance of intestinal microbiota and the imbalance is also associated with complications after SCI, possibly through the microbial-brain-gut axis. Melatonin is secreted in many parts of the body including pineal gland and gut, effectively protecting the spinal cord from secondary damage. The secretion of melatonin is affected by circadian rhythms, known as the dark light cycle, and SCI would also cause dysregulation of melatonin secretion. In addition, melatonin is closely related to the intestinal microbiota, which protects the barrier function of the gut through its antioxidant and anti-inflammatory effects, and increases the abundance of intestinal microbiota by influencing the metabolism of the intestinal microbiota. Furthermore, the intestinal microbiota can influence melatonin formation by regulating tryptophan and serotonin metabolism. This paper summarizes and reviews the knowledge on the relationship among intestinal microbiota, melatonin, and SCI in recent years, to provide new theories and ideas for clinical research related to SCI treatment.

The transcriptome profile of RPE cells by the fullerenol against hydrogen peroxide stress

Age-related macular degeneration (AMD) causes central vision impairment with increased incidence. In the pathogenesis of AMD, reactive oxygen species (ROS) are associated with RPE cell apoptosis. H₂O₂ is an oxidative toxicant and is used to establish the AMD in vitro model. However, the mechanisms of ROS in H₂O₂-induced AMD are still unclear. Fullerenol, a promising antioxidant of nanomaterials, protects RPE cells from ROS attack. In addition to working as a scavenger, little is known about the antioxidant mechanism of fullerenol in RPE cells. In this study, transcriptome sequencing was performed to examine the global changes in mRNA transcripts induced by H₂O₂ in human ARPE-19 cells. Moreover, we comprehensively investigated the protective effects of fullerenol against H₂O₂-induced oxidative injury by RNA sequencing. Gene Ontology enrichment analysis showed that those pathways related to the release of positive regulation of DNA-templated transcription and negative regulation of apoptotic process were affected. Finally, we found that 12 hub genes were related to the oxidative-protection function of fullerenol. In summary, H₂O₂ affected these hub genes and signaling pathways to regulate the senescence of RPE cells. Moreover, fullerenol is a potent nanomaterial that protects the RPE and would be a promising approach for AMD prevention.

Metformin improves depressive-like behavior in experimental Parkinson's disease by inducing autophagy in the substantia nigra and hippocampus

Parkinson's disease (PD) remains a disease of little known etiology. In addition to the motor symptoms, depression is present in about 40% of patients, contributing to the loss of quality of life. Recently, the involvement of the autophagy mechanism in the pathogenesis of depression has been studied, in addition to its involvement in PD as well. In this study, we tested the effects of metformin, an antidiabetic drug also with antidepressant effects, on depressive-like behavior in a rotenone-induced PD model and on the autophagy process. Mice 8-week-old male C57BL/6 were induced with rotenone for 20 consecutive days (2.5 mg/kg/day) and treated with metformin (200 mg/kg/day) from the 5th day of induction. All the animals were submitted to rotarod, sucrose preference and tail suspension tests. After euthanasia, the substantia nigra and hippocampus were removed for analysis by western blotting or fixed and analyzed by immunofluorescence. The results show that there was an impairment of autophagy in animals induced by rotenone both in nigral and extranigral regions as well as a depressive-like behavior. Metformin was able to inhibit depressive-like behavior and increase signaling pathway proteins, transcription factors and autophagosome-forming proteins, thus inducing autophagy in both the hippocampus and the substantia nigra. In conclusion, we show that metformin has an antidepressant effect in a rotenone-induced PD model, which may result, at least in part, from the induction of the autophagy process.

Melatonin attenuates polystyrene microplastics induced motor neurodevelopmental defect in zebrafish (Danio rerio) by activating nrf2 - isl2a Axis

Microplastics, a new type of ecological pollutant, have now become a major environmental concern worldwide. Polystyrene microplastics (PS), one of the most abundant form of microplastics, cause deleterious effects across species. Melatonin (MT), which is secreted by pineal gland, exhibits protective role against pollutant-induced damage. However, whether MT could ameliorate PS-induced neurodevelopmental toxicity remain unclear. In our study, zebrafish embryos were treated with PS (0.5, 25 mg/L) in the presence or absence of MT (1 μM) from 4 h post-fertilization (hpf) to 144 hpf. Locomotion behavior, oxidative stress, apoptosis, proliferation and development of caudal primary (Cap) motoneuron axon were analyzed. Gene expression was determined by qRT-PCR or whole-mount in situ hybridization. Results showed that PS exposure significantly reduced swimming speed of zebrafish larvae and induced excessive reactive oxygen species (ROS), apoptosis and aberrant proliferation. In addition, PS treatment markedly shortened the length of Cap motoneuron axons and decreased expression of neurodevelopment related genes. While, MT administration considerably rescued the neurodevelopmental toxicity of PS. Mechanistically, MT activated nrf2 (nuclear factor-E2-related factor 2) - isl2a (ISL LIM homeobox 2a) axis to antagonize the side effects of PS. In all, our findings suggest that PS exposure during early life lead to aberrant neurodevelopment of zebrafish, and MT might be a therapeutic option for protecting such disorder.

Melatonin improves bisphenol A-induced cell apoptosis, oxidative stress and autophagy impairment via inhibition of the p38 MAPK signaling pathway in FLK-BLV cells

The aim of this study was to assess the protective effect and potential mechanism of melatonin against bisphenol A (BPA)-induced apoptosis and oxidative damage in FLK-BLV cells. The results showed that BPA reduced cell viability in a dose- and time-dependent manner, caused cell shrinkage and induced oxidative stress and apoptosis in FLK-BLV cells, which were effectively reversed by melatonin. In addition, BPA caused autophagy flux impairment, which was confirmed by the increased of LC3-II and p62 levels, whereas melatonin treatment effectively reduced p62 levels under BPA treatment, and reversed apoptosis-related protein expression patterns caused by BPA. However, inhibition of autophagy by CQ partially abolished the protective effect of melatonin on apoptosis, suggesting that melatonin against BPA-induced oxidative injury and apoptosis by activating autophagy pathway. Moreover, we found that melatonin inhibited BPA-induced the activation of p38 MAPK, which was comparable to SB203580 pretreatment, and companied by the activation of autophagy and decreases of apoptosis when compared to BPA alone, indicating that melatonin protected against BPA-induced apoptosis partially through the p38 MAPK-autophagy pathway. In conclusion, these results suggest that melatonin may prevent BPA-induced FLK-BLV cell damage by inhibiting p38/MAPK signaling pathway and activating autophagy, and it could be a potential therapeutic compound in preventing BPA-induced cell damage.

Melatonin improves arsenic-induced hypertension through the inactivation of the Sirt1/autophagy pathway in rat

Arsenic (As), a metalloid chemical element, is classified as heavy metal. Previous studies proposed that As induces vascular toxicity by inducing autophagy, apoptosis, and oxidative stress. It has been shown that melatonin (Mel) can decrease oxidative stress and apoptosis, and modulate autophagy in different pathological situations. Hence, this study aimed to investigate the Mel effect on As-induced vascular toxicity through apoptosis and autophagy regulation. Forty male rats were treated with As (15 mg/kg; oral gavage) and Mel (10 and 20 mg/kg, intraperitoneally; i.p.) for 28 days. The systolic blood pressure (SBP) changes, oxidative stress markers, the aorta histopathological injuries, contractile and relaxant responses, the level of apoptosis (Bnip3 and caspase-3) and autophagy (Sirt1, Beclin-1 and LC3 II/I ratio) proteins were determined in rats aorta. The As exposure significantly increased SBP and enhanced MDA level while reduced GSH content. The exposure to As caused substantial histological damage in aorta tissue and changed vasoconstriction and vasorelaxation responses to KCl, PE, and Ach in isolated rat aorta. The levels of HO-1 and Nrf-2, apoptosis markers, Sirt1, and autophagy proteins also enhanced in As group. Interestingly, Mel could reduce changes in oxidative stress, blood pressure, apoptosis, and autophagy induced by As. On the other hand, Mel led to more increased the levels of Nrf-2 and HO-1 proteins compared with the As group. In conclusion, our findings showed that Mel could have a protective effect against As-induced vascular toxicity by inhibiting apoptosis and the Sirt1/autophagy pathway.

The effects and molecular mechanism of heat stress on spermatogenesis and the mitigation measures

Under normal conditions, to achieve optimal spermatogenesis, the temperature of the testes should be 2-6 °C lower than body temperature. Cryptorchidism is one of the common pathogenic factors of male infertility. The increase of testicular temperature in male cryptorchidism patients leads to the disorder of body regulation and balance, induces the oxidative stress response of germ cells, destroys the integrity of sperm DNA, yields morphologically abnormal sperm, and leads to excessive apoptosis of germ cells. These physiological changes in the body can reduce sperm fertility and lead to male infertility. This paper describes the factors causing testicular heat stress, including lifestyle and behavioral factors, occupational and environmental factors (external factors), and clinical factors caused by pathological conditions (internal factors). Studies have shown that wearing tight pants or an inappropriate posture when sitting for a long time in daily life, and an increase in ambient temperature caused by different seasons or in different areas, can cause an increase in testicular temperature, induces testicular oxidative stress response, and reduce male fertility. The occurrence of cryptorchidism causes pathological changes within the testis and sperm, such as increased germ cell apoptosis, DNA damage in sperm cells, changes in gene expression, increase in chromosome aneuploidy, and changes in Na⁺/K⁺-ATPase activity, etc. At the end of the article, we list some substances that can relieve oxidative stress in tissues, such as trigonelline, melatonin, R. apetalus, and angelica powder. These substances can protect testicular tissue and relieve the damage caused by excessive oxidative stress.

Melatonin Improved the Survival of Multi-Territory Perforator Flaps by Promoting Angiogenesis and Inhibiting Apoptosis via the NRF2/FUNDC1 Axis

Background: Multi-territory perforator flaps are a reconstructive measure for repairing large soft tissue defects caused by tumors or trauma. However, the use of these flaps in clinical practice has been restricted due to the uncertain blood supply. Therefore, promoting the survival of the multi-territory perforator flap is critical for clinical repair and reconstruction. In our study, we explored the effects of melatonin (MLT) on multi-territory perforator flaps and the possible molecular mechanisms.

Materials and Methods: Seventy-two Sprague–Dawley rats (250–300 g) were randomly divided into 3 groups (n = 24): Control, MLT and MLT + ML385 groups. First, we assessed the survival area of the flap, followed by the micro-vessel density and CD31-positive vessel expression. Apoptosis of the skin flap under immunofluorescence and expression of the apoptosis-related proteins Bcl-2, Bax and Caspase3 were measured. Additionally, angiogenesis of the skin flaps was shown by angiography, and NRF2 and FUNDC1 mRNA and protein expression was detected by real-time PCR and western blotting.

Results: The results showed that MLT increased the survival area of the multi-territory perforator flap, which was related to increased angiogenesis and decreased apoptosis. We also found that mRNA and protein of NRF2 and FUNDC1 levels were significantly increased after MLT treatment, and an NRF2 inhibitor reversed the ability of MLT to enhance multi-territory perforator flap survival, promote angiogenesis and inhibit apoptosis and reduced FUNDC1 protein expression.

Conclusion: MLT promoted angiogenesis and inhibited apoptosis to promote the survival of multi-territory perforator flaps, which may be regulated via the NRF2/FUNDC1 axis.

Decorin Protects Retinal Pigment Epithelium Cells from Oxidative Stress and Apoptosis via AMPK-mTOR-Regulated Autophagy

Age-related macular degeneration (AMD) is the leading cause of irreversible visual loss among the elderly worldwide with unidentified pathogenesis and limited therapeutic options. Oxidative stress-induced damage to the retinal pigment epithelium (RPE) is central in the development and progression of AMD. Decorin (DCN), a small leucine-rich proteoglycan, possesses powerful antifibrotic, anti-inflammatory, and antiangiogenic properties. DCN has also been reported to serve a cytoprotective role in various cell types, but its protective effects against H₂O₂-induced oxidative stress and apoptosis in ARPE-19 cells remain unclear. In this study, we showed that DCN significantly attenuated the increase in cell viability loss, apoptosis rate, and reactive oxygen species (ROS) levels in ARPE-19 cells induced by H₂O₂. Furthermore, DCN activated the AMPK/mTOR pathway to promote autophagy while genetic inhibition of autophagy-related gene 5 (ATG5) hindered autophagic process and diminished the protective role of DCN against oxidative stress in ARPE-19 cells. Collectively, these results suggest that DCN could protect RPE cells from H₂O₂-induced oxidative stress and apoptosis via autophagy promotion, thus providing the therapeutic potential for AMD prevention and treatment.

Differential susceptibility of retinal ganglion cell subtypes against neurodegenerative diseases

Retinal ganglion cells (RGCs) are essential to propagate external visual information from the retina to the brain. Death of RGCs is speculated to be closely correlated with blinding retinal diseases, such as glaucoma and traumatic optic neuropathy (TON). Emerging innovative technologies have helped refine and standardize the classification of RGCs; at present, they are classified into more than 40 subpopulations in mammals. These RGC subtypes are identified by a combination of anatomical morphologies, electrophysiological functions, and genetic profiles. Increasing evidence suggests that neurodegenerative diseases do not collectively affect the RGCs. In fact, which RGC subtype exhibits the strongest or weakest susceptibility is hotly debated. Although a consensus has not yet been reached, it is certain that assorted RGCs display differential susceptibility against irreversible degeneration. Interestingly, a single RGC subtype can exhibit various vulnerabilities to optic nerve damage in diverse injury models. Thus, elucidating how susceptible RGC subtypes are to various injuries can protect vulnerable RGCs from damage and improve the possibility of preventing and treating visual impairment caused by neurodegenerative diseases. In this review, we summarize in detail the progress and status quo of research on the type-specific susceptibility of RGCs and point out current limitations and the possible directions for future research in this field.

Oxidative Stress Enhances Autophagy-Mediated Death Of Stem Cells Through Erk1/2 Signaling Pathway - Implications For Neurotransplantations

Stem cell therapies are becoming increasingly popular solutions for neurological disorders. However, there is a lower survival rate of these cells after transplantation. Oxidative stress is linked to brain damage, and it may also impact transplanted stem cells. To better understand how transplanted cells respond to oxidative stress, the current study used H₂O₂. We briefly illustrated that exogenous H₂O₂ treatment exaggerated oxidative stress in the human dental pulp and mesenchymal stem cells. 2',7'-Dichlorofluorescin diacetate (DCFDA), MitoSOX confirms the reactive oxygen species (ROS) involvement, which was remarkably subsided by the ROS inhibitors. The findings showed that H₂O₂ activates autophagy by enhancing pro-autophagic proteins, Beclin1 and Atg7. Increased LC3II/I expression (which co-localized with lysosomal proteins, LAMP1 and Cathepsin B) showed that H₂O₂ treatment promoted autophagolysosome formation. In the results, both Beclin1 and Atg7 were observed co-localized in mitochondria, indicating their involvement in mitophagy. The evaluation of Erk1/2 in the presence and absence of Na-Pyruvate, PEG-Catalase, and PD98059 established ROS-Erk1/2 participation in autophagy regulation. Further, these findings showed a link between apoptosis and autophagy. The results conclude that H₂O₂ acts as a stressor, promoting autophagy and mitophagy in stem cells under oxidative stress. The current study may help understand better cell survival and death approaches for transplanted cells in various neurological diseases. The current study uses human Dental Pulp and Mesenchymal Stem cells to demonstrate the importance of H₂O₂-driven autophagy in deciding the fate of these cells in an oxidative microenvironment. To summarise, we discovered that exogenous H₂O₂ treatment causes oxidative stress. Exogenous H₂O₂  treatment also increased ROS production, especially intracellular H₂O₂. H₂O₂ stimulated the ErK1/2 signaling pathway and autophagy. Erk1/2 was found to cause autophagy. Further, the function of mitophagy appeared to be an important factor in the H₂O₂-induced regulation of these two human stem cell types. In a nutshell, by engaging in autophagy nucleation, maturation, and terminal phase proteins, we elucidated the participation of autophagy in cell dysfunction and death.

Melatonin as a powerful antioxidant

Melatonin is a hormone that has many body functions and, for several decades, its antioxidant potential has been increasingly talked about. There is a relationship between failure in melatonin production in the pineal gland, an insufficient supply of this hormone to the body, and the occurrence of free radical etiology diseases such as neurodegenerative diseases, cardiovascular diseases, diabetes, cancer and others. Despite the development of molecular biology, numerous in vitro and in vivo studies, the exact mechanism of melatonin antioxidant activity is still unknown. Nowadays, the use of melatonin supplementation is more and more common, not only to prevent insomnia, but also to slow down the aging process and provide protection against diseases. The aim of this study is to get acquainted with current reports on melatonin, antioxidative mechanisms and their importance in diseases of free radical etiology.

Eugenol-Induced Autophagy and Apoptosis in Breast Cancer Cells via PI3K/AKT/FOXO3a Pathway Inhibition

The use of natural compounds is promising in approaches to prevent and treat cancer. The long-term application of most currently employed chemotherapy techniques has toxic side effects. Eugenol, a phenolic phytochemical extracted from certain essential oils, has an anti-cancer effect. The modulation of autophagy can promote either the survival or apoptosis of cancer cells. Triple-negative (MDA-MB-231) and HER2 positive (SK-BR-3) breast cancer cell lines were treated with different doses of eugenol. Apoptosis was detected by a flow-cytometry technique, while autophagy was detected by acridine orange. Real-time PCR and Western blot assays were applied to investigate the effect of eugenol on the gene and protein expression levels of autophagy and apoptotic genes. Treating cells with different concentrations of eugenol significantly inhibited cell proliferation. The protein levels of AKT serine/threonine kinase 1 (AKT), forkhead box O3 (FOXO3a), cyclin dependent kinase inhibitor 1A (p21), cyclin-dependent kinase inhibitor (p27), and Caspase-3 and -9 increased significantly in Eugenol-treated cells. Eugenol also induced autophagy by upregulating the expression levels of microtubule-associated protein 1 light chain 3 (LC3) and downregulating the expression of nucleoporin 62 (NU p62). Eugenol is a promising natural anti-cancer agent against triple-negative and HER2-positive breast cancer. It appears to work by targeting the caspase pathway and by inducing autophagic cell death.

Mitochondrial Dysfunction and Endoplasmic Reticulum Stress in Age Related Macular Degeneration, Role in Pathophysiology, and Possible New Therapeutic Strategies

Age related macular degeneration (AMD) is the main cause of legal blindness in developed countries. It is a multifactorial disease in which a combination of genetic and environmental factors contributes to increased risk of developing this vision-incapacitating condition. Oxidative stress plays a central role in the pathophysiology of AMD and recent publications have highlighted the importance of mitochondrial dysfunction and endoplasmic reticulum stress in this disease. Although treatment with vascular endothelium growth factor inhibitors have decreased the risk of blindness in patients with the exudative form of AMD, the search for new therapeutic options continues to prevent the loss of photoreceptors and retinal pigment epithelium cells, characteristic of late stage AMD. In this review, we explain how mitochondrial dysfunction and endoplasmic reticulum stress participate in AMD pathogenesis. We also discuss a role of several antioxidants (bile acids, resveratrol, melatonin, humanin, and coenzyme Q10) in amelioration of AMD pathology.

Melatonin: a Potential Shield against Electromagnetic Waves

Melatonin, a vital hormone synthesized by the pineal gland, has been implicated in various physiological functions and in circadian rhythm regulation. Its role in the protection against the non-ionizing electromagnetic field (EMF), known to disrupt the body's oxidative/anti-oxidative balance, has been called into question due to inconsistent results observed across studies. This review provides the current state of knowledge on the interwoven relationship between melatonin, EMF, and oxidative stress. Based on synthesized evidence, we present a model that best describes the mechanisms underlying the protective effects of melatonin against RF/ELF-EMF induced oxidative stress. We show that the free radical scavenger activity of melatonin is enabled through reduction of the radical pair singlet-triplet conversion rate and the concentration of the triplet products. Moreover, this review aims to highlight the potential therapeutic benefits of melatonin against the detrimental effects of EMF, in general, and electromagnetic hypersensitivity (EHS), in particular.

Association between NF-kB polymorphism and age-related macular degeneration in a high-altitude population

Objective

To investigate the association between the nuclear factor kappa B (NF-kB) gene polymorphism and age-related macular degeneration (AMD) in a high-altitude population.

Methods

Fifty-five patients with AMD and 57 control subjects were recruited from the Qinghai Provincial People’s Hospital, China. Genomic DNA was extracted from the blood sample of each participant. Four NF-kB polymorphisms (rs3774959, rs3774932, rs3774937, and rs230526) were genotyped using a MassARRAY system. The genotype and allele frequencies were compared between the case and control groups using the chi-squared test or Fisher’s exact test.

Results

There was no significant difference in sex, age, hypertension, diabetes, blood lipid level or smoking and drinking status between the AMD and control groups (P > 0.05). The genotype distributions of four NF-kB polymorphisms were in accordance with Hardy-Weinberg equilibrium in the control group (P > 0.05). The frequencies of genotype AA of rs3774932 and genotype CC of rs3774937 were nominally significantly higher in the AMD group than in the control group (P = 0.046 and 0.023, respectively), although these associations did not survive the Bonferroni correction (corrected P > 0.05). Genotype distributions of rs3774959 and rs230526 were not significantly different between the two groups (P = 0.08 and 0.16, respectively). No significant difference in the allele frequencies of the four polymorphisms was found between the AMD and control groups (P > 0.05).

Conclusions

Genotype AA of rs3774932 and genotype CC of rs3774937 in NF-kB might be risk factors for AMD.

Melatonin Protects HT22 Hippocampal Cells from H2O2-induced Injury by Increasing Beclin1 and Atg Protein Levels to Activate Autophagy

BACKGROUND

The aging of hippocampal neurons leads to a substantial decline in memory formation, storage and processing. The neuroprotective effect of melatonin has been confirmed, however, its protective mechanism remains unclear.

OBJECTIVE

In this study, mouse hippocampus-derived neuronal HT22 cells were used to investigate whether melatonin protects the hippocampus from hydrogen peroxide (H₂O₂)-induced injury by regulating autophagy.

METHODS

Rapamycin (an activator of autophagy) and 3-methyladenine (3MA, an inhibitor of autophagy) were used to induce or inhibit autophagy, respectively. HT22 cells were treated with 200 μM H₂O₂ in the presence or absence of 50 μM melatonin. Cell counting kit 8 (CCK-8), β-galactosidase and Hoechst staining were used to measure the viability, aging and apoptosis of cells, respectively. Western blot analysis was used to detect the levels of autophagy-related proteins.

RESULTS

The activation of autophagy by rapamycin alleviated H₂O₂-induced oxidative injury, as evidenced by morphological changes and decreased viability, while the inhibition of autophagy by 3MA exacerbated H₂O₂- induced injury. The inhibitory effect of melatonin on H₂O₂-induced injury was similar to that of rapamycin. Melatonin also alleviated H₂O₂-induced aging and apoptosis. Melatonin activated autophagy in the presence or absence of H₂O₂, as evidenced by an increased Lc3b 14/16 kd ratio and a decreased P62 level. In addition, H2O2 decreased the levels of Beclin1 and Atg5/12/16, which were reversed by rapamycin or melatonin. The effects of melatonin on H₂O₂-induced injury, autophagy and protein expressions were effectively reversed by 3MA.

CONCLUSION

In conclusion, these results demonstrate that melatonin protects HT22 hippocampal neurons from H₂O₂-induced injury by increasing the levels of the Beclin1 and Atg proteins to activate autophagy.

Baicalin Prevents Myocardial Ischemia/Reperfusion Injury Through Inhibiting ACSL4 Mediated Ferroptosis

Baicalin is a natural flavonoid glycoside that confers protection against myocardial ischemia/reperfusion (I/R) injury. However, its mechanism has not been fully understood. This study focused on elucidating the role of ferroptosis in baicalin-generated protective effects on myocardial ischemia/reperfusion (I/R) injury by using the myocardial I/R rat model and oxygen–glucose deprivation/reoxygenation (OGD/R) H9c2 cells. Our results show that baicalin improved myocardial I/R challenge–induced ST segment elevation, coronary flow (CF), left ventricular systolic pressure , infarct area, and pathological changes and prevented OGD/R-triggered cell viability loss. In addition, enhanced lipid peroxidation and significant iron accumulation along with activated transferrin receptor protein 1 (TfR1) signal and nuclear receptor coactivator 4 (NCOA4)-medicated ferritinophagy were observed in in vivo and in vitro models, which were reversed by baicalin treatment. Furthermore, acyl-CoA synthetase long-chain family member 4 (ACSL4) overexpression compromised baicalin-generated protective effect in H9c2 cells. Taken together, our findings suggest that baicalin prevents against myocardial ischemia/reperfusion injury via suppressing ACSL4-controlled ferroptosis. This study provides a novel target for the prevention of myocardial ischemia/reperfusion injury.

Prophylactic Melatonin Treatment Ameliorated Propofol-Induced Cognitive Dysfunction in Aged Rats

Considering the fact that melatonin acts as protective agent in various cognitive impairment, we decided to explore the precise effect of pretreatment with melatonin on cognitive function, mitochondrial activity, apoptosis and synaptic integrity in aged rats anesthetized by propofol. We first randomly allocated the thirty Sprague Dawley rats into three groups: Control vehicle-treated group (Con), Propofol-treated group (Pro) and Melatonin + Propofol group (Mel + Pro). The Barnes maze, open field and contextual fear conditioning test were employed to evaluate spatial memory, exploratory behavior and general locomotor activity, and hippocampus-dependent learning and memory ability, respectively. Moreover, mitochondrial function (including reactive oxygen species, mitochondrial membrane potential and ATP levels) and apoptosis were detected in the regions of hippocampus (HIP) and prefrontal cortex (PFC). The results of behavioral tests suggested that melatonin improved propofol-induced memory impairment in aged rats. Melatonin mitigated mitochondrial dysfunction and decreased the apoptotic cell counts in the regions of HIP and PFC. Furthermore, prophylactic melatonin treatment also reversed the propofol-induced inactivation of PKA/CREB/BDNF signaling and synaptic dysfunction. On the whole, our results indicated that melatonin ameliorated the propofol-induced cognitive disorders via attenuating mitochondrial dysfunction, apoptosis, inactivation of PKA/CREB/BDNF signaling and synaptic dysfunction.

SS-31 protect retinal pigment epithelial cells from H2 O2 -induced cell injury by reducing apoptosis

Evidence has shown that effects from oxidative stress induced damage of retinal or human retinal pigment epithelial (RPE) cells. Antioxidant supplementation is a plausible strategy to avoid oxidative stress and maintain the function of retina. d‐Arg‐2,6‐dimethyltyrosine‐Lys‐Phe‐NH2 (SS‐31) has been used in the treatment of many diseases. In this study, we found that SS‐31 attenuated hydrogen peroxide (H₂O₂)‐induced loss of cell viability, reduced oxidative damage and cell apoptosis in RPE cells. HO‐1, Trx‐1 and Nrf‐2 expression levels significantly increased on pre‐treatment with SS‐31 compared with the H₂O₂ group. SS‐31 inhibited apoptosis through the downregulation of Bax and the upregulation of Bcl‐2. Our results suggest that SS‐31 had a protective effect against H₂O₂ treatment in ARPE‐19 cells by enhancing the antioxidative enzymes expression and decreasing apoptosis, which could be considered a promising therapeutic intervention for retinal degeneration.

The Role of Autophagy in Eye Diseases

Autophagy is a catabolic process that ensures homeostasis in the cells of our organism. It plays a crucial role in protecting eye cells against oxidative damage and external stress factors. Ocular pathologies of high incidence, such as age-related macular degeneration, cataracts, glaucoma, and diabetic retinopathy are of multifactorial origin and are associated with genetic, environmental factors, age, and oxidative stress, among others; the latter factor is one of the most influential in ocular diseases, directly affecting the processes of autophagy activity. Alteration of the normal functioning of autophagy processes can interrupt organelle turnover, leading to the accumulation of cellular debris and causing physiological dysfunction of the eye. The aim of this study is to review research on the role of autophagy processes in the main ocular pathologies, which have a high incidence and result in high costs for the health system. Considering the role of autophagy processes in cell homeostasis and cell viability, the control and modulation of autophagy processes in ocular pathologies could constitute a new therapeutic approach.

Influence of Circadian Rhythm in the Eye: Significance of Melatonin in Glaucoma

Circadian rhythm and the molecules involved in it, such as melanopsin and melatonin, play an important role in the eye to regulate the homeostasis and even to treat some ocular conditions. As a result, many ocular pathologies like dry eye, corneal wound healing, cataracts, myopia, retinal diseases, and glaucoma are affected by this cycle. This review will summarize the current scientific literature about the influence of circadian patterns on the eye, focusing on its relationship with increased intraocular pressure (IOP) fluctuations and glaucoma. Regarding treatments, two ways should be studied: the first one, to analyze if some treatments could improve their effect on the ocular disease when their posology is established in function of circadian patterns, and the second one, to evaluate new drugs to treat eye pathologies related to the circadian rhythm, as it has been stated with melatonin or its analogs, that not only could be used as the main treatment but as coadjutant, improving the circadian pattern or its antioxidant and antiangiogenic properties.

Lower Plasma Melatonin in the Intervertebral Disk Degeneration Patients Was Associated with Increased Proinflammatory Cytokines

Background

Intervertebral disc degeneration (IDD) was considered to be the pathological basis of intervertebral disc herniation (IDH). However, the plasma melatonin in the IDD cases and healthy controls remained unclear.

Methods

In this case–control study, a total of 71 IDD cases and 54 healthy controls were enrolled between April 2020 and August 2020. The diagnostic effect of plasma melatonin for IDD was detected using receiver operating characteristic curve. The correlations between two continuous variables were detected with the Pearson linear analyses.

Results

It was found that lower melatonin concentration was detected in the IDD cases (1.906 ± 1.041 vs 3.072 ± 0.511 pg/mL, P<0.001). Through receiver operating characteristic curve analyses, it was found that plasma melatonin could be used as a diagnostic biomarker for IDD (area under curve=0.808, P<0.001). In advanced correlation analyses, it was found that plasma melatonin concentration was negatively associated with the age, symptom durations, IDD disease severity and proinflammatory factors, including IL-6 and TNF-α concentrations (P<0.05). Comparing with the higher melatonin groups, significantly increased IL-6 (0.601 ± 0.085 vs 0.507 ± 0.167 pg/mL, P=0.028) and TNF-α (3.022 ± 0.286 vs 2.353 ± 0.641, P<0.001) were detected in the patients with lower melatonin concentration.

Conclusion

The plasma melatonin concentration was significantly decreased in the IDD cases and plasma melatonin could be used as a diagnostic biomarker for IDD. Lower plasma melatonin was associated with longer disease durations, elevated disease severity and higher inflammatory cytokines levels in IDD patients.

The relationship between endoplasmic reticulum stress and autophagy in apoptosis of BEAS-2B cells induced by cigarette smoke condensate

Cigarette smoke (CS) is one of the severe risk factors for the development of the pulmonary disease. However, the underlying mechanisms, especially the CS-induced the human bronchial epithelial cells (BEAS-2B) apoptosis related to endoplasmic reticulum stress (ERS) and autophagy, remains to be studied. This study aims to investigate the relationship between ERS and autophagy in apoptosis induced by CS condensate (CSC). BEAS-2B cells were stimulated with 0.02, 0.04 and 0.08 mg/ml CSC for 24 h to detect the ERS, autophagy and apoptosis. Then, ERS and autophagy of BEAS-2B cells were inhibited, respectively, by using 4-PBA and 3-MA, and followed by CSC treatment. The results showed that CSC decreased cell viability, increased cell apoptosis, elevated cleaved-caspase 3/pro-caspase 3 ratio and Bax expressions, but decreased Bcl-2 expressions. The GRP78 and CHOP expressions and LC3-II/LC3-I ratio were dose-dependently increased. The structure of the endoplasmic reticulum was abnormal and the number of autolysosomes was increased in BEAS-2B cells after CSC stimulation. The LC3-II/LC3-I ratio was decreased after ERS inhibition with 4-PBA, but GRP78 and CHOP expressions were enhanced after autophagy inhibition with 3-MA. CSC-induced apoptosis was further increased, Bax expressions and cleaved-caspase 3/pro-caspase 3 ratio were improved, but Bcl-2 expressions were decreased after 3-MA or 4-PBA treatment. In conclusion, the study indicates that ERS may repress apoptosis of BEAS-2B cells induced by CSC via activating autophagy, but autophagy relieves ERS in a negative feedback. This study provides better understanding and experimental support on the underlying mechanisms of pulmonary disease stimulated by CS.

Hydrogen Sulfide Protects Retinal Pigment Epithelial Cells from Oxidative Stress-Induced Apoptosis and Affects Autophagy

Age-related macular degeneration (AMD) is a major cause of visual impairment and blindness among the elderly. AMD is characterized by retinal pigment epithelial (RPE) cell dysfunction. However, the pathogenesis of AMD is still unclear, and there is currently no effective treatment. Accumulated evidence indicates that oxidative stress and autophagy play a crucial role in the development of AMD. H2S is an antioxidant that can directly remove intracellular superoxide anions and hydrogen peroxide. The purpose of this study is to investigate the antioxidative effect of H2S in RPE cells and its role in autophagy. The results show that exogenous H2S (NaHS) pretreatment effectively reduces H2O2-induced oxidative stress, oxidative damage, apoptosis, and inflammation in ARPE-19 cells. NaHS pretreatment also decreased autophagy levels raised by H2O2, increased cell viability, and ameliorated cell morphological damage. Interestingly, the suppression of autophagy by its inhibitor 3-MA showed an increase of cell viability, amelioration of morphology, and a decrease of apoptosis. In summary, oxidative stress causes ARPE-19 cell injury by inducing cell autophagy. However exogenous H2S is shown to attenuate ARPE-19 cell injury, decrease apoptosis, and reduce the occurrence of autophagy-mediated by oxidative stress. These findings suggest that autophagy might play a crucial role in the development of AMD, and exogenous H2S has a potential value in the treatment of AMD.

Melatonin prevents the binding of vascular endothelial growth factor to its receptor and promotes the expression of extracellular matrix-associated genes in nucleus pulposus cells

The mechanisms of intervertebral disc degeneration (IDD) involve numerous factors, including loss of the extracellular matrix (ECM) and vascular ingrowth. Melatonin has been reported to protect intervertebral discs (IVDs) from degeneration and to exert a potential anti-angiogenic effect. The aim of the present study was to investigate the anti-angiogenic and anabolic effects of melatonin in IVDs. Human nucleus pulposus (NP) and degenerative nucleus pulposus (DNP) cells were isolated and treated with melatonin. The results indicated that melatonin promoted ECM synthesis and NP cell proliferation. In addition, an NP/DNP and human umbilical vein endothelial cell (HUVEC) co-culture model was used to investigate the anti-angiogenesis effect of melatonin. Melatonin was indicated to suppress tube formation and migration of HUVECs in culture with NP cell-conditioned medium, as well as in an NP cell co-culture model. Fluorescence-labeled vascular endothelial growth factor (VEGF) was used to study the binding between VEGF and its receptor. The results of the present study indicated that melatonin exerts an angiogenic effect via inhibition of the binding of VEGF to its receptor in HUVECs. Taken together, these results suggest that melatonin is a potential agent to prevent IDD.

High-Fat Diet-Induced Functional and Pathologic Changes in Lacrimal Gland

The lacrimal gland is critical for maintaining the homeostasis of the ocular surface microenvironment through secreting aqueous tears in mammals. Many systemic diseases such as Sjögren syndrome, rheumatoid arthritis, and diabetes can alter the lacrimal gland function, eventually resulting in aqueous tear-deficient dry eye. Here, a high-fat diet (HFD) experimental mouse model was used to clarify how hyperlipidemia affects lacrimal gland function. Aqueous tear secretion fell about 50% after 1 month on a HFD. Lipid droplets accumulated in the matrix and acinar cells of the lacrimal gland after this period, along with changes in the lipid metabolism, changes in gene expression levels, and disruption of fatty acid oxidative activity. Immune cell infiltration and rises in the gene expression levels of the inflammation-related cytokines Il1β, Tnfα, Tsg6, Il10, Mmp2, and Mmp9 were found. HFD also induced mitochondrial hypermegasoma, increased apoptosis, and decreased lacrimal gland acinar cell proliferation. Replacement of the HFD with the standard diet partially reversed pathologic changes in the lacrimal gland. Similarly, supplementing the HFD with fenofibrate also partially reversed the inhibited tear secretion and reduced lipid accumulation, inflammation, and oxidative stress levels. The authors conclude that a HFD induces pathophysiological changes and functional decompensation of the lacrimal gland. Therefore, ingestion of a HFD may be a causative factor of dry eye disease.

Ozone treatment for high-dose systemic Steroid-Induced retinal injury

OBJECTIVE

To investigate the effect of high-dose systemic steroids on retinal tissues and the effectiveness of ozone (O3) therapy.

METHODS

Twenty-four New Zealand white rabbits were divided into three groups of eight. Group 1 was accepted as the control group, Group 2 received intramuscular 20 mg/kg methylprednisolone acetate and Group 3 received 14 sessions of ozone treatment in addition to methylprednisolone acetate. The subjects were sacrificed on the 30th day. Retinal tissues were removed. Superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), total antioxidant status (TAS) and total oxidant status (TOS) levels were evaluated for tissue biochemistry and serum ischaemic modified albumin (IMA), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) levels were evaluated with the ELISA method. Haematoxylin-eosin staining and TUNEL evaluation for apoptosis were evaluated as histopathological methods.

RESULTS

In the treatment group, antioxidant parameters of TAS, SOD and CAT were higher, oxidative and ischaemic parameters of MDA, TOS and IMA were lower, inflammatory parameters of IL-6 and TNF-α were lower, retinal thickness was better and apoptosis amount was lower.

CONCLUSION

Apoptosis increases in retinal tissues due to high dose systemic steroid administration and the retina becomes thinner. With biochemical examination, oxidation parameters increased while antioxidant parameters decreased. Both histopathological and biochemical parameters improved significantly with ozone treatment.

Autophagy in Age-Related Macular Degeneration: A Regulatory Mechanism of Oxidative Stress

Age-related macular degeneration (AMD) is a leading cause of severe visual loss and irreversible blindness in the elderly population worldwide. Retinal pigment epithelial (RPE) cells are the major site of pathological alterations in AMD. They are responsible for the phagocytosis of shed photoreceptor outer segments (POSs) and clearance of cellular waste under physiological conditions. Age-related, cumulative oxidative stimuli contribute to the pathogenesis of AMD. Excessive oxidative stress induces RPE cell degeneration and incomplete digestion of POSs, leading to the continuous accumulation of cellular waste (such as lipofuscin). Autophagy is a major system of degradation of damaged or unnecessary proteins. However, degenerative RPE cells in AMD patients cannot perform autophagy sufficiently to resist oxidative damage. Increasing evidence supports the idea that enhancing the autophagic process can properly alleviate oxidative injury in AMD and protect RPE and photoreceptor cells from degeneration and death, although overactivated autophagy may lead to cell death at early stages of retinal degenerative diseases. The crosstalk among the NFE2L2, PGC-1, p62, AMPK, and PI3K/Akt/mTOR pathways may play a crucial role in improving disturbed autophagy and mitigating the progression of AMD. In this review, we discuss how autophagy prevents oxidative damage in AMD, summarize potential neuroprotective strategies for therapeutic interventions, and provide an overview of these neuroprotective mechanisms.

Mesenchymal Stem Cell Secretome Enhancement by Nicotinamide and Vasoactive Intestinal Peptide: A New Therapeutic Approach for Retinal Degenerative Diseases

Mesenchymal stem cells (MSC) secrete neuroprotective molecules that may be useful as an alternative to cell transplantation itself. Our purpose was to develop different pharmaceutical compositions based on conditioned medium (CM) of adipose MSC (aMSC) stimulated by and/or combined with nicotinamide (NIC), vasoactive intestinal peptide (VIP), or both factors; and to evaluate in vitro their proliferative and neuroprotective potential. Nine pharmaceutical compositions were developed from 3 experimental approaches: (1) unstimulated aMSC-CM collected and combined with NIC, VIP, or both factors (NIC+VIP), referred to as the aMSC-CM combined composition; (2) aMSC-CM collected just after stimulation with the mentioned factors and containing them, referred to as the aMSC-CM stimulated-combined composition; and (3) aMSC-CM previously stimulated with the factors, referred to as the aMSC stimulated composition. The potential of the pharmaceutical compositions to increase cell proliferation under oxidative stress and neuroprotection were evaluated in vitro by using a subacute oxidative stress model of retinal pigment epithelium cells (line ARPE-19) and spontaneous degenerative neuroretina model. Results showed that oxidatively stressed ARPE-19 cells exposed to aMSC-CM stimulated and stimulated-combined with NIC or NIC+VIP tended to have better recovery from the oxidative stress status. Neuroretinal explants cultured with aMSC-CM stimulated-combined with NIC+VIP had better preservation of the neuroretinal morphology, mainly photoreceptors, and a lower degree of glial cell activation. In conclusion, aMSC-CM stimulated-combined with NIC+VIP contributed to improving the proliferative and neuroprotective properties of the aMSC secretome. Further studies are necessary to evaluate higher concentrations of the drugs and to characterize specifically the aMSC-secreted factors related to neuroprotection. However, this study supports the possibility of improving the potential of new effective pharmaceutical compositions based on the secretome of MSC plus exogenous factors or drugs without the need to inject cells into the eye, which can be very useful in retinal pathologies.