Tribulus terrestris Ameliorates Oxidative Stress-Induced ARPE-19 Cell Injury through the PI3K/Akt-Nrf2 Signaling Pathway

Regulatory factors of Nrf2 in age-related macular degeneration pathogenesis

Age-related macular degeneration (AMD) is a complicated disease that causes irreversible visual impairment. Increasing evidences pointed retinal pigment epithelia (RPE) cells as the decisive cell involved in the progress of AMD, and the function of anti-oxidant capacity of PRE plays a fundamental physiological role. Nuclear factor erythroid 2 related factor 2 (Nrf2) is a significant transcription factor in the cellular anti-oxidant system as it regulates the expression of multiple anti-oxidative genes. Its functions of protecting RPE cells against oxidative stress (OS) and ensuing physiological changes, including inflammation, mitochondrial damage and autophagy dysregulation, have already been elucidated. Understanding the roles of upstream regulators of Nrf2 could provide further insight to the OS-mediated AMD pathogenesis. For the first time, this review summarized the reported upstream regulators of Nrf2 in AMD pathogenesis, including proteins and miRNAs, and their underlying molecular mechanisms, which may help to find potential targets via regulating the Nrf2 pathway in the future research and further discuss the existing Nrf2 regulators proved to be beneficial in preventing AMD.

Immunomodulatory effects of Kaempferol on microglial and Macrophage cells during the progression of diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) stands as a prevalent secondary complication of diabetes, notably Type 1 Diabetes Mellitus (T1D), characterized by immune system involvement potentially impacting the retinal immune response mediated by microglia. Early stages of DR witness blood-retinal barrier permeabilization, facilitating peripheral immune cell interaction with the retinal immune system. Kaempferol (Kae), known for its potent anti-inflammatory activity, presents a promising avenue in DR treatment by targeting the immune mechanisms underlying its onset and progression. Our investigation delves into the molecular intricacies of innate immune cell interaction during DR progression and the attenuation of inflammatory processes pivotal to its pathology.

METHODS

Employing in vitro studies, we exposed HAPI microglial and J774.A1 macrophage cells to pro-inflammatory stimuli in the presence or absence of Kae. Ex vivo and in vivo experiments utilized BB rats, a T1D animal model. Retinal explants from BB rats were cultured with Kae, while intraperitoneal Kae injections were administered to BB rats for 15 days. Quantitative PCR, Western blotting, immunofluorescence, and Spectral Domain - Optical Coherence Tomography (SD-OCT) facilitated survival assessment, cellular signaling analysis, and inflammatory marker determination.

RESULTS

Results demonstrate Kae significantly mitigates inflammatory processes across in vitro, ex vivo, and in vivo DR models, primarily targeting immune cell responses. Kae administration notably inhibits proinflammatory responses during DR progression while promoting an anti-inflammatory milieu, chiefly through microglia-mediated synthesis of Arginase-1 and Hemeoxygenase-1(HO-1). In vivo, Kae administration effectively preserves retinal integrity amid DR progression.

CONCLUSIONS

Our findings elucidate the interplay between retinal and systemic immune cells in DR progression, underscoring a differential treatment response predominantly orchestrated by microglia's anti-inflammatory action. Kae treatment induces a phenotypic and functional shift in immune cells, delaying DR progression, thereby spotlighting microglial cells as a promising therapeutic target in DR management.

Combination Therapy with N-Acetylserotonin and Aflibercept Activated the Akt/Nrf2 Pathway to Inhibit Apoptosis and Oxidative Stress in Rats with Retinal Ischemia-Reperfusion Injury

PURPOSE

N-acetylserotonin (NAS) can reduce retinal ischemia-reperfusion injury (RIRI) by inhibiting the TLR4/NF-κB/NLRP3 signaling pathway. Aflibercept is an anti-VEGF drug used to treat a variety of eye diseases. This study was performed to investigate the effect of combination therapy with N-acetylserotonin and aflibercept on RIRI and its mechanism.

METHODS

The RIRI model was established by elevating the intraocular pressure. H&E staining was used to observe the pathological changes in the retinal tissue. Cell apoptosis was evaluated by TUNEL. The expression of cleaved caspase-3 in the retina was detected by immunofluorescence and western blotting. The levels of SOD, GSH-Px, and MDA in retinal tissue were measured by ELISA. The protein expression of cytoplasmic Nrf2, nuclear Nrf2, HO-1, Akt, and p-Akt was determined by western blotting.

RESULTS

The results showed that combination therapy with NAS and aflibercept significantly alleviated retinal histopathological damage, decreased retinal thickness (from 335.49 ± 30.50 µm to 226.16 ± 17.20 µm, p < 0.001) and the rate of retinal apoptosis (from 28.27 ± 0.39% to 7.87 ± 0.19%, p < 0.001), and downregulated protein expression (from 2.42 ± 0.03 to 1.39 ± 0.03, p < 0.001) and positive expression (from 31.88 ± 0.52 to 25.36 ± 0.58, p < 0.001) of cleaved caspase-3. In addition, combination therapy with NAS and aflibercept also upregulated the levels of SOD (from 20.31 ± 0.18 to 29.66 ± 0.83, p < 0.001) and GSH-Px (from 13.62 ± 0.36 to 19.31 ± 0.82, p < 0.001) and downregulated the level of MDA (from 0.51 ± 0.01 to 0.41 ± 0.01, p < 0.001) to inhibit oxidative stress. Finally, combination therapy with NAS and aflibercept increased the protein expression of cytoplasmic Nrf2 (from 0.10 ± 0.002 to 0.85 ± 0.01, p < 0.001), nuclear Nrf2 (from 0.43 ± 0.01 to 0.88 ± 0.04, p < 0.001), and HO-1 (from 0.45 ± 0.03 to 0.91 ± 0.04, p < 0.001) and the p-Akt/Akt ratio (from 0.45 ± 0.02 to 0.81 ± 0.07, p < 0.001).

CONCLUSIONS

Overall, combination therapy with NAS and aflibercept attenuated RIRI, and its mechanism may be related to inhibiting apoptosis and oxidative stress and activating the Akt/Nrf2 pathway.

Piceid Octanoate Protects Retinal Cells against Oxidative Damage by Regulating the Sirtuin 1/Poly-ADP-Ribose Polymerase 1 Axis In Vitro and in rd10 Mice

Retinitis pigmentosa is a common cause of inherited blindness in adults, which in many cases is associated with an increase in the formation of reactive oxygen species (ROS) that induces DNA damage, triggering Poly-ADP-Ribose Polymerase 1 (PARP1) activation and leading to parthanatos-mediated cell death. Previous studies have shown that resveratrol (RSV) is a promising molecule that can mitigate PARP1 overactivity, but its low bioavailability is a limitation for medical use. This study examined the impact of a synthesized new acylated RSV prodrug, piceid octanoate (PIC-OCT), in the 661W cell line against H2O2 oxidative stress and in rd10 mice. PIC-OCT possesses a better ADME profile than RSV. In response to H2O2, 661W cells pretreated with PIC-OCT preserved cell viability in more than 38% of cells by significantly promoting SIRT1 nuclear translocation, preserving NAD+/NADH ratio, and suppressing intracellular ROS formation. These effects result from expressing antioxidant genes, maintaining mitochondrial function, reducing PARP1 nuclear expression, and preventing AIF nuclear translocation. In rd10 mice, PIC-OCT inhibited PAR-polymer formation, increased SIRT1 expression, significantly reduced TUNEL-positive cells in the retinal outer nuclear layer, preserved ERGs, and enhanced light chamber activity (all p values < 0.05). Our findings corroborate that PIC-OCT protects photoreceptors by modulating the SIRT1/PARP1 axis in models of retinal degeneration.

Circ-CARD6 inhibits oxidative stress-induced apoptosis and autophagy in ARPE-19 cells via the miR-29b-3p/PRDX6/PI3K/Akt axis

BACKGROUND

Oxidative stress-induced damage and dysfunction of retinal pigment epithelium (RPE) cells are important pathogenetic factors of age-related macular degeneration (AMD) and hereditary retinopathy diseases (HRDs). This study aimed to elucidate the roles and mechanisms of circ-CARD6 and miR-29b-3p in oxidative stress-induced RPE and provide new ideas for the diagnosis and treatment of retinopathy disease (RD).

METHODS

A model of oxidative stress-induced RPE (ARPE-19) was established, and the level of malondialdehyde (MDA) and concentration of reactive oxygen species (ROS) were detected by a DCFH-DA fluorescent probe and MDA kit. The cell viability was measured by a CCK-8 assay. The expression of PRDX6/PI3K/Akt axis genes and proteins related to apoptosis and autophagy were determined by RT‒qPCR and Western blot analyses. The dual-luciferase reporter system confirmed the targeting relationship between miR-29b-3p and circ-CARD6 and between miR-29b-3p and PRDX6.

RESULTS

In H2O2-treated ARPE-19 cells, the expression of circ-CARD6 and PRDX6 was decreased, while the expression of miR-29b-3p was increased. The overexpression of circ-CARD6 inhibits oxidative stress-induced increases in ROS, apoptosis and autophagy in ARPE-19 cells. circ-CARD6 targets miR-29b-3p, miR-29b-3p targets PRDX6, and circ-CARD6 regulates PRDX6 via miR-29b-3p. Further studies showed that circ-CARD6 acts as a competitive endogenous RNA of miR-29b-3p to affect the expression of PRDX6, thereby inhibiting autophagy and apoptosis in ARPE-19 cells.

CONCLUSION

circ-CARD6 can inhibit oxidative stress and apoptosis by regulating the miR-29b-3p/PRDX6/PI3K/Akt axis.

Low-dose Lipopolysaccharide Alleviates Spinal Cord Injury-induced Neuronal Inflammation by Inhibiting microRNA-429-mediated Suppression of PI3K/AKT/Nrf2 Signaling

This study investigated the impact of low-dose lipopolysaccharide (LPS) on spinal cord injury (SCI) and the potential molecular mechanism. Rats were randomly assigned to four groups: Sham, SCI, SCI + LPS, and SCI + LPS + agomir. Allen's weight-drop method was used to establish an in vivo SCI model. The Basso Bcattie Bresnahan rating scale was employed to monitor locomotor function. An in vitro SCI model was constructed by subjecting PC12 cells to oxygen and glucose deprivation/ reoxygenation (OGD/R). Enzyme-linked immunosorbent assay (ELISA) was applied for the determination interleukin (IL)-1β and IL-6. The dual luciferase reporter assay was used to validate the targeting of microRNA (miR)-429 with PI3K. Immunohistochemical staining was used to assess the expression of PI3K, phosphorylated AKT and Nrf2 proteins. The Nrf2-downstream anti-oxidative stress proteins, OH-1 and NQO1, were detected by western blot assay. MiR-429 expression was detected by fluorescence in situ hybridization and real-time quantitative reverse transcription PCR. In vitro, low-dose LPS decreased miR-429 expression, activated PI3K/AKT/Nrf2, inhibited oxidative stress and inflammation, and attenuated SCI. MiR-429 was found to target and negatively regulate PI3K. Inhibition of miR-429 suppressed low-dose LPS-mediated oxidative stress and inflammation via activation of the PI3K/AKT/Nrf2 pathway. In vivo, miR-429 was detectable in neurons. Inhibition of miR-429 blocked low-dose LPS-mediated oxidative stress and inflammation via activation of the PI3K/AKT/Nrf2 pathway. Overall, low-dose LPS was found to alleviate SCI-induced neuronal oxidative stress and inflammatory response by down-regulating miR-429 to activate the PI3K/AKT/Nrf2 pathway.

Buspirone Enhances Cell Survival and Preserves Structural Integrity during Oxidative Injury to the Retinal Pigment Epithelium

Chronic oxidative stress impairs the normal functioning of the retinal pigment epithelium (RPE), leading to atrophy of this cell layer in cases of advance age-related macular degeneration (AMD). The purpose of our study was to determine if buspirone, a partial serotonin 1A (5-HT1A) receptor agonist, protected against oxidative stress-induced changes in the RPE. We exposed differentiated human ARPE-19 cells to paraquat to induce oxidative damage in culture, and utilized a mouse model with sodium iodate (NaIO3)-induced oxidative injury to evaluate the effect of buspirone. To investigate buspirone's effect on protective gene expression, we performed RT-PCR. Cellular toxicities and junctional abnormalities due to paraquat induction in ARPE-19 cells and buspirone's impact were assessed via WST-1 assays and ZO-1 immunostaining. We used spectral-domain optical coherence tomography (SD-OCT) and ZO-1 immunostaining of RPE/choroid for structural analysis. WST-1 assays showed dose-dependent protection of viability in buspirone-treated ARPE-19 cells in culture and preservation of RPE junctional integrity under oxidative stress conditions. In the NaIO3 model, daily intraperitoneal injection (i.p.) of buspirone (30 mg/kg) for 12 days improved the survival of photoreceptors compared to those of vehicle-treated eyes. ZO-1-stained RPE flat-mounts revealed the structural preservation of RPE from oxidative damage in buspirone-treated mice, as well as in buspirone-induced Nqo1, Cat, Sqstm1, Gstm1, and Sod2 genes in the RPE/choroid compared to untreated eyes. Since oxidative stress is implicated in the pathogenesis AMD, repurposing buspirone, which is currently approved for the treatment of anxiety, might be useful in treating or preventing dry AMD.

Multi-omics reveals the mechanisms underlying Lactiplantibacillus plantarum P8-mediated attenuation of oxidative stress in broilers challenged with dexamethasone

Oxidative stress is a common phenomenon in poultry production. Several molecules, including antioxidant genes, miRNAs, and gut microbiota metabolites, have been reported to participate in redox regulation. Lactiplantibacillus plantarum P8 (P8) was shown to improve the antioxidant capacity of chickens, but the specific molecular mechanisms remain unclear. In this study, 400 broilers were allocated to 4 treatment groups: control diet (Con group), control diet + dexamethasone injection (DEX group), control diet containing 1 × 108 CFU/g P8 (P8 group), and control diet containing 1 × 108 CFU/g P8 + DEX injection (DEX_P8 group). Integrated analysis of the microbiome, metabolomics, and miRNAomics was conducted to investigate the roles of P8 in oxidative stress in broilers. Results demonstrated that P8 supplementation significantly improved growth performance, jejunal morphology, and antioxidant function in DEX-treated broilers. Analysis of the gut microbiota revealed a higher abundance of Barnesiella (P = 0.01) and Erysipelatoclostridium (P = 0.05) in the DEX_P8 group than in the DEX group. Functional prediction indicated that certain pathways, including the phenylacetate degradation pathway, were enriched in the DEX_P8 group compared to the DEX group. Metabolites in the cecal contents were distinct between the groups. P8 supplementation increased the content of metabolites with antioxidant capacity, e.g., urobilinogen (P < 0.01), and decreased that of metabolites related to oxidative stress, e.g., genistein (P < 0.01). Functional prediction indicated that metabolites that differed between the DEX_P8 and DEX groups were enriched in pathways including "tryptophan metabolism" and "primary bile acid biosynthesis". The miRNAomics analysis further showed that, compared to the DEX group, several miRNAs in the jejunum, such as gga-miR-21-3p (P = 0.03), were increased, whereas gga-miR-455-3p (P = 0.02) was decreased in the DEX_P8 group. The PI3K-Akt, Ras, and Rap1 signaling pathways were enriched in the DEX_P8 group compared to the DEX group through KEGG analysis. Correlation analysis revealed potential interactions between growth performance, oxidation/antioxidation, jejunal morphology, gut microbiota, cecal content metabolites, and jejunal miRNAs. Overall, our results indicate that P8 supplementation may improve the growth performance, jejunal morphology and antioxidant capacity of DEX-treated broilers by regulating gut microbiota, its metabolites, and intestinal miRNAs.

Discovering the Potential of Natural Antioxidants in Age-Related Macular Degeneration: A Review

Age-related macular degeneration (AMD) is a multifactorial disease associated with anatomical changes in the inner retina. Despite tremendous advances in clinical care, there is currently no cure for AMD. This review aims to evaluate the published literature on the therapeutic roles of natural antioxidants in AMD. A literature search of PubMed, Web of Science and Google Scholar for peer-reviewed articles published between 1 January 2011 and 31 October 2021 was undertaken. A total of 82 preclinical and 18 clinical studies were eligible for inclusion in this review. We identified active compounds, carotenoids, extracts and polysaccharides, flavonoids, formulations, vitamins and whole foods with potential therapeutic roles in AMD. We evaluated the integral cellular signaling pathways including the activation of antioxidant pathways and angiogenesis pathways orchestrating their mode of action. In conclusion, we examined the therapeutic roles of natural antioxidants in AMD which warrant further study for application in clinical practice. Our current understanding is that natural antioxidants have the potential to improve or halt the progression of AMD, and tailoring therapeutics to the specific disease stages may be the key to preventing irreversible vision loss.

MiR-125b attenuates retinal pigment epithelium oxidative damage via targeting Nrf2/HIF-1α signal pathway

The retinal pigment epithelium cells (RPE) are sensitive to oxidative stimuli due to long-term exposure to various environmental stimuli. Thus, the oxidative injury of RPE cells caused by the imbalance of redox homeostasis is one of the main pathogenic factors of age-related macular degeneration (AMD). But the sophisticated mechanisms linking AMD to oxidative stress are not fully elucidated. Activation of Nrf2 signal pathway can protect RPE cells from oxidative damage. The present study investigated the regulating mechanism of miR-125b in Nrf2 cascade and evaluated its antioxidant capacity. The in vitro studies indicated that overexpression of miR-125b substantially inhibited Keap1 expression, enhanced Nrf2 expression and induced Nrf2 nuclear translocation. Importantly, functional studies demonstrated that forced expression of miR-125b could significantly elevate cell proliferation and superoxide dismutase (SOD) levels while reduce reactive oxygen species (ROS) overproduction and malondialdehyde (MDA) formation. Further studies showed that miR-125b had no effect when Nrf2 was silenced in ARPE-19 cells. Additionally, the results identified that Nrf2 silence induced ROS accumulation enhances HIF-1α protein expression, while miR-125b could offset this effect via promoting HIF-1α protein degradation. Subsequent in vivo studies demonstrated that sodium iodate induced outer retina thinner was reversed with exogenous supplementation of miR-125b, which was cancelled in Nrf2 knockout mice. In conclusion, this study illustrated that miR-125b can protect RPE from oxidative damage via targeting Nrf2/HIF-1α signal pathway and potentially may serve as a therapeutic agent of AMD.

Puncture vine (Tribulus Terrestris L.) in control of health and reproduction

Tribulus terrestris, L. (puncture vine) have been used as a folk medicine for five thousands of years, but its targets, effects, their mechanisms and application requires further studies. This paper reviews the provenance, constituents and properties of Tribulus terrestris, L., its general physiological and health effects, as well as the currently available knowledge concerning its influence on male and female reproductive processes and their dysfunctions. Analysis of the available publications demonstrated the influence of Tribulus terrestris on a wide spectrum of targets and physiological processe and disorders. In particular, Tribulus terrestris can be a stimulator of male and female reproductive processes at the level of central nervous system, sexual behaviour, pituitary and gonadal hormones and their receptors, gonadal functions (including ovarian follicullogenesis and spermatogenesis), improvement of the quality and quantity of gametes (at least of sperm) and fecundity. This ability of puncture vine is applicable for the improvement of man's sexual desire and sperm quality in vivo and in vitro, as well as of women's libido, activation of women's reproductive organs, fecundity, and treatment of infertility, especially that related to the polycystic ovarian syndrome.

Puncture vine (Tribulus Terrestris L.) in control of health and reproduction

Tribulus terrestris, L. (puncture vine) have been used as a folk medicine for five thousands of years, but its targets, effects, their mechanisms and application requires further studies. This paper reviews the provenance, constituents and properties of Tribulus terrestris, L., its general physiological and health effects, as well as the currently available knowledge concerning its influence on male and female reproductive processes and their dysfunctions. Analysis of the available publications demonstrated the influence of Tribulus terrestris on a wide spectrum of targets and physiological processe and disorders. In particular, Tribulus terrestris can be a stimulator of male and female reproductive processes at the level of central nervous system, sexual behaviour, pituitary and gonadal hormones and their receptors, gonadal functions (including ovarian follicullogenesis and spermatogenesis), improvement of the quality and quantity of gametes (at least of sperm) and fecundity. This ability of puncture vine is applicable for the improvement of man’s sexual desire and sperm quality in vivo and in vitro, as well as of women’s libido, activation of women’s reproductive organs, fecundity, and treatment of infertility, especially that related to the polycystic ovarian syndrome.

Tribulus terrestris L. protects glomerular endothelial cells via the miR155-H2AC6 interaction network in hypertensive renal injury

Background

Hypertensive renal injury is one of the most lethal complications of hypertension. At present, renin-angiotensin-aldosterone system (RAAS) blockers are considered the best drugs for the treatment of renal injury in hypertension because of their nephroprotective effect of reducing proteinuria, but there are no specific drugs for this purpose, however, clinical trials proved that Chinese medicine has a protective effect on target organs in the treatment of hypertension. Tribulus terrestris L. (TrT), a traditional Chinese medicine (TCM), has potential applications due to its reno-protective and immunomodulatory effects.

Methods

We investigated the underlying reno-protective mechanism of TrT on Angiotensin II (AngII)-induced hypertensive renal injury in glomerular endothelial cells by integrating the differential expression profiles of micro RNA (miRNA) and messenger RNA (mRNA) to construct a miRNA-mRNA interaction network associated with hypertensive kidney injury, followed by quantitative real-time polymerase chain reaction (qRT-PCR) for validation.

Results

Seventy-six differentially expressed mRNAs (DEmRNAs) and 1 differentially expressed miRNAs (DEmiRNAs) were identified in the control group and the AngII-induced hypertensive renal injury group, respectively. 110 DEmRNAs and 27 DEmiRNAs were identified in the TrT treatment group and the AngII-induced group, respectively. The core component of the miRNA-mRNA network was miR-155-5p. Our study showed that miR-155-5p expression levels were more decreased in the AngII-induced hypertensive renal injury group than the control group. TrT treatment also significantly upregulated miR-155-5p. Additionally, we found that miR-155-5p expression levels were negatively correlated with H2A clustered histone 6 (H2AC6).

Conclusions

The results of this study indicate that TrT has a reno-protective effect on AngII-induced hypertensive renal injury by miR-155-5p, which negatively regulates the expression of H2AC6. Our findings offer a new therapeutic strategy and have identified an effective candidate target for the treatment of hypertensive renal injury in clinical settings.

Exploration of the Effect and Mechanism of Fructus Lycii, Rehmanniae Radix Praeparata, and Paeonia lactiflora in the Treatment of AMD Based on Network Pharmacology and in vitro Experimental Verification

Purpose

The aim of this study was to observe the mechanism of Fructus Lycii (FL), Rehmanniae Radix Praeparata (RRP) and Paeonia lactiflora (PL) in treating age-related macular degeneration (AMD) based on network pharmacology and biological experiments.

Methods

Bioactive compounds, potential targets of FL, RRP and PL, and genes related to AMD, were acquired from public databases. Functional and pathway enrichment analyses of the core targets were conducted by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Subsequently, the finding was further verified with cell experiments. The MTT assay and flow cytometric analysis were used to assess cell viability and apoptosis. The production of reactive oxygen species (ROS) was analyzed by DCFH-DA staining; the activity of antioxidant enzymes was chemically measured with assay kits. The expression of key proteins was evaluated by Western blot analysis.

Results

Fifty-nine active compounds, 182 potential targets, and 2536 AMD-related human genes were identified. A total of 103 key targets of the three herbs on AMD were identified by protein-protein interaction (PPI) analysis. The abovementioned targets were correlated with nuclear receptor activity, oxidative stress, and apoptosis pathways according to the GO and KEGG analyses. MTT assay and flow cytometry demonstrated that pretreatment of ARPE-19 cells with the three herbs significantly increased cell viability and decreased apoptosis induced by H₂O₂. The three herbs might reduce the intracellular ROS levels and increase the SOD and CAT activities after H₂O₂. Furthermore, the three herbs significantly inhibited oxidative stress via increasing the expression of Nrf2, HO-1 and NQO1.

Conclusion

The combined results of network pharmacology and validation experiments showed that FL, RRP and PL reduce oxidative stress and apoptosis in RPE cells to exert its effect in the treatment of AMD.

Pathophysiological Basis for Nutraceutical Supplementation in Heart Failure: A Comprehensive Review

There is evidence demonstrating that heart failure (HF) occurs in 1-2% of the global population and is often accompanied by comorbidities which contribute to increasing the prevalence of the disease, the rate of hospitalization and the mortality. Although recent advances in both pharmacological and non-pharmacological approaches have led to a significant improvement in clinical outcomes in patients affected by HF, residual unmet needs remain, mostly related to the occurrence of poorly defined strategies in the early stages of myocardial dysfunction. Nutritional support in patients developing HF and nutraceutical supplementation have recently been shown to possibly contribute to protection of the failing myocardium, although their place in the treatment of HF requires further assessment, in order to find better therapeutic solutions. In this context, the Optimal Nutraceutical Supplementation in Heart Failure (ONUS-HF) working group aimed to assess the optimal nutraceutical approach to HF in the early phases of the disease, in order to counteract selected pathways that are imbalanced in the failing myocardium. In particular, we reviewed several of the most relevant pathophysiological and molecular changes occurring during the early stages of myocardial dysfunction. These include mitochondrial and sarcoplasmic reticulum stress, insufficient nitric oxide (NO) release, impaired cardiac stem cell mobilization and an imbalanced regulation of metalloproteinases. Moreover, we reviewed the potential of the nutraceutical supplementation of several natural products, such as coenzyme Q10 (CoQ10), a grape seed extract, Olea Europea L.-related antioxidants, a sodium-glucose cotransporter (SGLT2) inhibitor-rich apple extract and a bergamot polyphenolic fraction, in addition to their support in cardiomyocyte protection, in HF. Such an approach should contribute to optimising the use of nutraceuticals in HF, and the effect needs to be confirmed by means of more targeted clinical trials exploring the efficacy and safety of these compounds.

Esculetin protects human corneal epithelial cells from oxidative stress through Nrf-2 signaling pathway

Dry eye formation often originates from oxidative damage to the ocular surface, which can be caused by external environment or internal pathologic factors. Esculetin (6, 7-dihydroxycoumarin) is a natural product found in many plants, and has been reported to have multiple pharmacological activities. The objective of our present study is to investigate if esculetin could protect the corneal epithelial cells from oxidative damages and its underlying antioxidant molecular mechanisms. Our experimental results demonstrated that pretreatment with esculetin markedly increased the cell viability while decreased the apoptosis in H₂O₂-treated human corneal epithelial (HCE) cells, by regulating Bcl-2, Bax and caspase-3 protein expressions and by altering the imbalance of activities of intracellular reactive oxygen species (ROS) and superoxide dismutase (SOD). Our data revealed that esculetin played an antioxidant role not only through its antioxidant activity, but also by highly inducing Nrf-2 translocation to the nucleus, which in turn, enhanced Nrf2 signaling regulated antioxidant genes (HO-1, NQO1, GCLM, SOD1 and SOD2) mRNA expression levels in H₂O₂-treated HCE cells. In the present study, the protective effects of esculetin on the corneal epithelium were also confirmed by a murine desiccating stress induced dry eye model in vivo. These data illustrated, for the first time, that esculetin may have the ability to protect human corneal epithelial cells from oxidative damages through its scavenging of free radical properties and through the activation of Nrf2 signaling.