Natural compounds and retinal ganglion cell neuroprotection

Exploring Epigenetic Modifications as Potential Biomarkers and Therapeutic Targets in Glaucoma

Glaucoma, a complex and multifactorial neurodegenerative disorder, is a leading cause of irreversible blindness worldwide. Despite significant advancements in our understanding of its pathogenesis and management, early diagnosis and effective treatment of glaucoma remain major clinical challenges. Epigenetic modifications, encompassing deoxyribonucleic acid (DNA) methylation, histone modifications, and non-coding RNAs, have emerged as critical regulators of gene expression and cellular processes. The aim of this comprehensive review focuses on the emerging field of epigenetics and its role in understanding the complex genetic and molecular mechanisms underlying glaucoma. The review will provide an overview of the pathophysiology of glaucoma, emphasizing the intricacies of intraocular pressure regulation, retinal ganglion cell dysfunction, and optic nerve damage. It explores how epigenetic modifications, such as DNA methylation and histone modifications, can influence gene expression, and how these mechanisms are implicated in glaucomatous neurodegeneration and contribute to glaucoma pathogenesis. The manuscript discusses evidence from both animal models and human studies, providing insights into the epigenetic alterations associated with glaucoma onset and progression. Additionally, it discusses the potential of using epigenetic modifications as diagnostic biomarkers and therapeutic targets for more personalized and targeted glaucoma treatment.

Integrative transcriptome and metabolome analysis reveals the discrepancy in the accumulation of active ingredients between Lycium barbarum cultivars

MAIN CONCLUSION

The combined analysis of transcriptome and metabolome provided molecular insight into the dynamics of multiple active ingredients biosynthesis and accumulation across different cultivars of Lycium barbarum. Lycium barbarum L. has a high concentration of active ingredients and is well known in traditional Chinese herbal medicine for its therapeutic properties. However, there are many Lycium barbarum cultivars, and the content of active components varies, resulting in inconsistent quality between Lycium barbarum cultivars. At present, few research has been conducted to reveal the difference in active ingredient content among different cultivars of Lycium barbarum at the molecular level. Therefore, the transcriptome of 'Ningqi No.1' and 'Qixin No.1' during the three development stages (G, T, and M) was constructed in this study. A total of 797,570,278 clean reads were obtained. Between the two types of wolfberries, a total of 469, 2394, and 1531 differentially expressed genes (DEGs) were obtained in the 'G1 vs. G10,' 'T1 vs. T10,' and 'M1 vs. M10,' respectively, and were annotated with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology identifiers. Using these transcriptome data, most DEGs related to the metabolism of the active ingredients in 'Ningqi No.1' and 'Qixin No.1' were identified. Moreover, a widely targeted metabolome analysis of the metabolites of 'Ningqi 1' and 'Qixin 1' fruits at the maturity stage revealed 1,135 differentially expressed metabolites (DEMs) in 'M1 vs. M10,' and many DEMs were associated with active ingredients such as flavonoids, alkaloids, terpenoids, and so on. We further quantified the flavonoid, lignin, and carotenoid contents of the two Lycium barbarum cultivars during the three developmental stages. The present outcome provided molecular insight into the dynamics of multiple active ingredients biosynthesis and accumulation across different cultivars of Lycium barbarum, which would provide the basic data for the formation of Lycium barbarum fruit quality and the breeding of outstanding strains.

Trends in development and quality assessment of pharmaceutical formulations - F2α analogues in the glaucoma treatment

The ocular delivery route presents a number of challenges in terms of drug administration and bioavailability. The low bioavailability following topical ophthalmic administration shows that there is a clear need for in-depth research aimed at finding both more efficacious molecules and formulations precisely targeted at the site of action. Continuous technological development will eventually result in improved bioavailability, lower dosages, reduced toxicity, fewer adverse effects, and thus better patient compliance and treatment efficacy. Technological development, as well as increasingly stringent quality requirements, help stimulate analytical progress. This is also clearly evident in the case of medicinal products used in the treatment of glaucoma, which are the subject of this review. Impurity profiling of PGF2α analogues, either in the pure substance or in the finished formulation, is a crucial step in assessing their quality. The development of specific, accurate and precise stability-indicating analytical methods for determining the content and related substances seems to be an important issue in relation to this tasks. A total of 27 official and in-house analytical methods are presented that are used for the analysis of latanoprost, travoprost and bimatoprost. The conditions for chromatographic separation with UV or MS/MS detection and the available results obtained during method validation are described. In addition, several aspects are discussed, with particular emphasis on the instability of the analogues in aqueous solution and the phenomenon of isomerism, which affects a potentially large number of degradation products.

Using Computational Drug-Gene Analysis to Identify Novel Therapeutic Candidates for Retinal Neuroprotection

Retinal cell death is responsible for irreversible vision loss in many retinal disorders. No commercially approved treatments are currently available to attenuate retinal cell loss and preserve vision. We seek to identify chemicals/drugs with thoroughly-studied biological functions that possess neuroprotective effects in the retina using a computational bioinformatics approach. We queried the National Center for Biotechnology Information (NCBI) to identify genes associated with retinal neuroprotection. Enrichment analysis was performed using ToppGene to identify compounds related to the identified genes. This analysis constructs a Pharmacome from multiple drug-gene interaction databases to predict compounds with statistically significant associations to genes involved in retinal neuroprotection. Compounds with known deleterious effects (e.g., asbestos, ethanol) or with no clinical indications (e.g., paraquat, ozone) were manually filtered. We identified numerous drug/chemical classes associated to multiple genes implicated in retinal neuroprotection using a systematic computational approach. Anti-diabetics, lipid-lowering medicines, and antioxidants are among the treatments anticipated by this analysis, and many of these drugs could be readily repurposed for retinal neuroprotection. Our technique serves as an unbiased tool that can be utilized in the future to lead focused preclinical and clinical investigations for complex processes such as neuroprotection, as well as a wide range of other ocular pathologies.

Wolfberry genomes and the evolution of Lycium (Solanaceae)

Wolfberry Lycium, an economically important genus of the Solanaceae family, contains approximately 80 species and shows a fragmented distribution pattern among the Northern and Southern Hemispheres. Although several herbaceous species of Solanaceae have been subjected to genome sequencing, thus far, no genome sequences of woody representatives have been available. Here, we sequenced the genomes of 13 perennial woody species of Lycium, with a focus on Lycium barbarum. Integration with other genomes provides clear evidence supporting a whole-genome triplication (WGT) event shared by all hitherto sequenced solanaceous plants, which occurred shortly after the divergence of Solanaceae and Convolvulaceae. We identified new gene families and gene family expansions and contractions that first appeared in Solanaceae. Based on the identification of self-incompatibility related-gene families, we inferred that hybridization hotspots are enriched for genes that might be functioning in gametophytic self-incompatibility pathways in wolfberry. Extremely low expression of LOCULE NUBER (LC) and COLORLESS NON-RIPENING (CNR) orthologous genes during Lycium fruit development and ripening processes suggests functional diversification of these two genes between Lycium and tomato. The existence of additional flowering locus C-like MADS-box genes might correlate with the perennial flowering cycle of Lycium. Differential gene expression involved in the lignin biosynthetic pathway between Lycium and tomato likely illustrates woody and herbaceous differentiation. We also provide evidence that Lycium migrated from Africa into Asia, and subsequently from Asia into North America. Our results provide functional insights into Solanaceae origins, evolution and diversification.

Searching for the Antioxidant, Anti-Inflammatory, and Neuroprotective Potential of Natural Food and Nutritional Supplements for Ocular Health in the Mediterranean Population

Adherence to a healthy diet offers a valuable intervention to compete against the increasing cases of ocular diseases worldwide, such as dry eye disorders, myopia progression, cataracts, glaucoma, diabetic retinopathy, or age macular degeneration. Certain amounts of micronutrients must be daily provided for proper functioning of the visual system, such as vitamins, carotenoids, trace metals and omega-3 fatty acids. Among natural foods, the following have to be considered for boosting eye/vision health: fish, meat, eggs, nuts, legumes, citrus fruits, nuts, leafy green vegetables, orange-colored fruits/vegetables, olives-olive oil, and dairy products. Nutritional supplements have received much attention as potential tools for managing chronic-degenerative ocular diseases. A systematic search of PubMed, Web of Science, hand-searched publications and historical archives were performed by the professionals involved in this study, to include peer-reviewed articles in which natural food, nutrient content, and its potential relationship with ocular health. Five ophthalmologists and two researchers collected the characteristics, quality and suitability of the above studies. Finally, 177 publications from 1983 to 2021 were enclosed, mainly related to natural food, Mediterranean diet (MedDiet) and nutraceutic supplementation. For the first time, original studies with broccoli and tigernut (chufa de Valencia) regarding the ocular surface dysfunction, macular degeneration, diabetic retinopathy and glaucoma were enclosed. These can add value to the diet, counteract nutritional defects, and help in the early stages, as well as in the course of ophthalmic pathologies. The main purpose of this review, enclosed in the Special Issue "Health Benefits and Nutritional Quality of Fruits, Nuts and Vegetables," is to identify directions for further research on the role of diet and nutrition in the eyes and vision, and the potential antioxidant, anti-inflammatory and neuroprotective effects of natural food (broccoli, saffron, tigernuts and walnuts), the Mediterranean Diet, and nutraceutic supplements that may supply a promising and highly affordable scenario for patients at risk of vision loss. This review work was designed and carried out by a multidisciplinary group involved in ophthalmology and ophthalmic research and especially in nutritional ophthalmology.

In Silico Analysis of Forskolin as a Potential Inhibitor of SARS-CoV-2

Coronavirus disease 2019 (COVID–19) has spread rapidly as global pandemic affecting 187 countries/ regions and emerged as worldwide health crisis. Potential antiviral drugs used for the SARS -CoV-2 in clinical treatments have side effects. However, emergency vaccines are in use but despite that increase in the coronavirus cases are alarming. Thus, it is utmost need of safer antiviral agent to treat or inhibit the viral infection. Forskolin has been reported as a possible antiviral-agent. This molecule was docked with ACE2 receptor of human which is the target for the binding of S1 unit of viral S protein of SARS-CoV- 2. In silico docking was carried out on SwissDock, PatchDock and FireDock servers. The docked ACE2 structure was further docked with the RBD of the spike protein. Forskolin is able to H-bond with the hACE2 and ACE2-forskolin fails to interact with the receptor-binding domain (RBD) of the Spike protein of SARS-CoV-2. Instead, viral RBD is repulsed by the diterpene molecule through obliteration and reciprocated binding. We report first that forskolin plays a crucial role in the inhibition of protein-protein interaction of RBD and ACE2 when docked with either of the protein.

Anti-inflammatory Effect of Curcumin, Homotaurine, and Vitamin D3 on Human Vitreous in Patients With Diabetic Retinopathy

Purpose: To determine the levels of pro-inflammatory cytokines and soluble mediators (TNF-α, IL6, IL2, and PDGF-AB) in 28 vitreous biopsies taken from patients with proliferative diabetic retinopathy (PDR) and treated with increasing doses of curcumin (0. 5 and 1 μM), with or without homotaurine (100 μM) and vitamin D3 (50 nM). Materials and Methods: ELISA tests were performed on the supernatants from 28 vitreous biopsies that were incubated with bioactive molecules at 37°C for 20 h. The concentration of the soluble mediators was calculated from a calibration curve and expressed in pg/mL. Shapiro-Wilk test was used to verify the normality of distribution of the residuals. Continuous variables among groups were compared using the General Linear Model (GLM). Homoscedasticity was verified using Levene and Brown-Forsythe tests. Post-hoc analysis was also performed with the Tukey test. A p ≤ 0.05 was considered statistically significant. Results: The post-hoc analysis revealed statistically detectable changes in the concentrations of TNF-α, IL2, and PDGF-AB in response to the treatment with curcumin, homotaurine, and vitamin D3. Specifically, the p-values for between group comparisons are as follows: TNF-α: (untreated vs. curcumin 0.5 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.008, (curcumin 0.5 μM vs. curcumin 0.5 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.0004, (curcumin 0.5 μM vs. curcumin 1 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.02, (curcumin 1 μM vs. curcumin 0.5 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.025, and (homotaurine 100 μM + vitamin D3 50 nM vs. curcumin 0.5 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.009; IL2: (untreated vs. curcumin 0.5 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.0023, and (curcumin 0.5 μM vs. curcumin 0.5 μM+ homotaurine 100 μM + vitamin D3 50 nM) p = 0.0028; PDGF-AB: (untreated vs. curcumin 0.5 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.04, (untreated vs. curcumin 1 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.0006, (curcumin 0.5 μM vs. curcumin 1 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.006, and (homotaurine 100 μM + vitamin D3 50 nM vs. curcumin 1 μM + homotaurine 100 μM + vitamin D3 50 nM) p = 0.022. IL6 levels were not significantly affected by any treatment. Conclusions: Pro-inflammatory cytokines are associated with inflammation and angiogenesis, although there is a discrete variability in the doses of the mediators investigated among the different vitreous samples. Curcumin, homotaurine, and vitamin D3 individually have a slightly appreciable anti-inflammatory effect. However, when used in combination, these substances are able to modify the average levels of the soluble mediators of inflammation and retinal damage. Multi-target treatment may provide a therapeutic strategy for diabetic retinopathy in the future. Clinical Trial Registration : The trial was registered at clinical trials.gov as NCT04378972 on 06 May 2020 ("retrospectively registered") https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid = S0009UI8&selectaction = Edit&uid = U0003RKC&ts = 2&cx = dstm4o.

Novel Drug Delivery Systems Fighting Glaucoma: Formulation Obstacles and Solutions

Glaucoma is considered to be one of the biggest health problems in the world. It is the main cause of preventable blindness due to its asymptomatic nature in the early stages on the one hand and patients' non-adherence on the other. There are several approaches in glaucoma treatment, whereby this has to be individually designed for each patient. The first-line treatment is medication therapy. However, taking into account numerous disadvantages of conventional ophthalmic dosage forms, intensive work has been carried out on the development of novel drug delivery systems for glaucoma. This review aims to provide an overview of formulation solutions and strategies in the development of in situ gel systems, nanosystems, ocular inserts, contact lenses, collagen corneal shields, ocular implants, microneedles, and iontophoretic devices. The results of studies confirming the effectiveness of the aforementioned drug delivery systems were also briefly presented.

Common aspects between glaucoma and brain neurodegeneration

Neurodegeneration can be defined as progressive cell damage to nervous system cells, and more specifically to neurons, which involves morphologic alterations and progressive loss of function until cell death. Glaucoma exhibits many aspects of neurodegenerative disease. This review examines the pathogenesis of glaucoma, comparing it with that of Alzheimer's disease (AD) and Parkinson's disease (PD), highlighting their common features. Indeed, in all three diseases there are not only the same types of pathogenic events, but also similarities of temporal cadences that determine neuronal damage. All three age-related illnesses have oxidative damage and mitochondrial dysfunction as the first pathogenic steps. The consequence of these alterations is the death of visual neurons in glaucoma, cognitive neurons in AD and regulatory motor neurons (substantia nigra) in PD. The study of these common pathogenic events (oxidative stress, mitochondrial dysfunction, protein degradation, apoptosis and autophagy) leads us to consider common therapeutic strategies for the treatment and prevention of these diseases. Also, examination of the genetic aspects of the pathways involved in neurodegenerative processes plays a key role in shedding light on the details of pathogenesis and can suggest new treatments. This review discusses the common molecular aspects involved in these three oxidative-stress and age-related diseases.

The role of neuroinflammation in the pathogenesis of glaucoma neurodegeneration

The chapter is a review enclosed in the volume "Glaucoma: A pancitopatia of the retina and beyond." No cure exists for glaucoma. Knowledge on the molecular and cellular alterations underlying glaucoma neurodegeneration (GL-ND) includes innovative and path-breaking research on neuroinflammation and neuroprotection. A series of events involving immune response (IR), oxidative stress and gene expression are occurring during the glaucoma course. Uveitic glaucoma (UG) is a prevalent acute/chronic complication, in the setting of chronic anterior chamber inflammation. Managing the disease requires a team approach to guarantee better results for eyes and vision. Advances in biomedicine/biotechnology are driving a tremendous revolution in ophthalmology and ophthalmic research. New diagnostic and imaging modalities, constantly refined, enable outstanding criteria for delimiting glaucomatous neurodegeneration. Moreover, biotherapies that may modulate or inhibit the IR must be considered among the first-line for glaucoma neuroprotection. This review offers the readers useful and practical information on the latest updates in this regard.

Role of Mesenchymal Stem Cells in Counteracting Oxidative Stress-Related Neurodegeneration

Neurodegenerative diseases include a variety of pathologies such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, and so forth, which share many common characteristics such as oxidative stress, glycation, abnormal protein deposition, inflammation, and progressive neuronal loss. The last century has witnessed significant research to identify mechanisms and risk factors contributing to the complex etiopathogenesis of neurodegenerative diseases, such as genetic, vascular/metabolic, and lifestyle-related factors, which often co-occur and interact with each other. Apart from several environmental or genetic factors, in recent years, much evidence hints that impairment in redox homeostasis is a common mechanism in different neurological diseases. However, from a pharmacological perspective, oxidative stress is a difficult target, and antioxidants, the only strategy used so far, have been ineffective or even provoked side effects. In this review, we report an analysis of the recent literature on the role of oxidative stress in Alzheimer’s and Parkinson’s diseases as well as in amyotrophic lateral sclerosis, retinal ganglion cells, and ataxia. Moreover, the contribution of stem cells has been widely explored, looking at their potential in neuronal differentiation and reporting findings on their application in fighting oxidative stress in different neurodegenerative diseases. In particular, the exposure to mesenchymal stem cells or their secretome can be considered as a promising therapeutic strategy to enhance antioxidant capacity and neurotrophin expression while inhibiting pro-inflammatory cytokine secretion, which are common aspects of neurodegenerative pathologies. Further studies are needed to identify a tailored approach for each neurodegenerative disease in order to design more effective stem cell therapeutic strategies to prevent a broad range of neurodegenerative disorders.

Visual Defects and Ageing

Many diseases are related to age, among these neurodegeneration is particularly important. Alzheimer's disease Parkinson's and Glaucoma have many common pathogenic events including oxidative damage, Mitochondrial dysfunction, endothelial alterations and changes in the visual field. These are well known in the case of glaucoma, less in the case of neurodegeneration of the brain. Many other molecular aspects are common, such as the role of endoplasmic reticulum autophagy and neuronal apoptosis while others have been neglected due to lack of space such as inflammatory cytokine or miRNA. Moreover, the loss of specific neuronal populations, the induction of similar mechanisms of cell injury and the deposition of protein aggregates in specific anatomical areas are very similar events between these diseases. Intracellular and/or extracellular accumulation of protein aggregates is a key feature of many neurodegenerative disorders. The existence of abnormal protein aggregates has been documented in the RGCs of glaucomatous patients such as the anomalous Tau protein or the β-amyloid accumulations. Intra-cell catabolic processes also appear to be common in both glaucoma and neurodegeneration. They also help us to understand how the basis between these diseases is common and how the visual aspects can be a serious problem for those who are affected.

In Vivo Evaluation of PAX6 Overexpression and NMDA Cytotoxicity to Stimulate Proliferation in the Mouse Retina

Retinal degenerative diseases, due to the lack of regeneration systems and self-renewable cells, often lead to visual impairment. Pax6 is a pleiotropic transcription factor and its expression level determines self-renewal status or differentiation of retinal cells. Here, we investigated the fate of simultaneous induction of retinal ganglion cell death and Pax6 overexpression in retro-differentiation of retinal cells and their commitment to re-enter into the cell cycle. Induction of acute retinal ganglion cell death and generation of mouse experimental model was performed by N-methyl D-aspartic acid (NMDA) injection. Recombinant AAV2 virus harboring PAX6 cDNA and reporter gene was injected into untreated and model mouse eyes. Histological analyses, including IHC and retinal flatmounts immunostaining were performed. The number of Ki67+ cells was clearly increased in model mice, presumably due to NMDA treatment and regardless of Pax6 over-expression. Unlike previous studies, Ki67+ cells were found in GCL layer and interestingly ONL cells expressed Sox2 stemness marker after NMDA cytotoxicity. The potential of retinal cells for robust Ki67 expression, after injury, and expression of Sox2, confirmed their intrinsic plasticity and made a vivid prospect for retinal regenerative medicine.

Neuroprotective strategies for retinal disease

Diseases that affect the eye, including photoreceptor degeneration, diabetic retinopathy, and glaucoma, affect 11.8 million people in the US, resulting in vision loss and blindness. Loss of sight affects patient quality of life and puts an economic burden both on individuals and the greater healthcare system. Despite the urgent need for treatments, few effective options currently exist in the clinic. Here, we review research on promising neuroprotective strategies that promote neuronal survival with the potential to protect against vision loss and retinal cell death. Due to the large number of neuroprotective strategies, we restricted our review to approaches that we had direct experience with in the laboratory. We focus on drugs that target survival pathways, including bile acids like UDCA and TUDCA, steroid hormones like progesterone, therapies that target retinal dopamine, and neurotrophic factors. In addition, we review rehabilitative methods that increase endogenous repair mechanisms, including exercise and electrical stimulation therapies. For each approach, we provide background on the neuroprotective strategy, including history of use in other diseases; describe potential mechanisms of action; review the body of research performed in the retina thus far, both in animals and in humans; and discuss considerations when translating each treatment to the clinic and to the retina, including which therapies show the most promise for each retinal disease. Despite the high incidence of retinal diseases and the complexity of mechanisms involved, several promising neuroprotective treatments provide hope to prevent blindness. We discuss attractive candidates here with the goal of furthering retinal research in critical areas to rapidly translate neuroprotective strategies into the clinic.

Neuroprotection by (endo)Cannabinoids in Glaucoma and Retinal Neurodegenerative Diseases

BACKGROUND

Emerging neuroprotective strategies are being explored to preserve the retina from degeneration, that occurs in eye pathologies like glaucoma, diabetic retinopathy, age-related macular degeneration, and retinitis pigmentosa. Incidentally, neuroprotection of retina is a defending mechanism designed to prevent or delay neuronal cell death, and to maintain neural function following an initial insult, thus avoiding loss of vision.

METHODS

Numerous studies have investigated potential neuroprotective properties of plant-derived phytocannabinoids, as well as of their endogenous counterparts collectively termed endocannabinoids (eCBs), in several degenerative diseases of the retina. eCBs are a group of neuromodulators that, mainly by activating G protein-coupled type-1 and type-2 cannabinoid (CB1 and CB2) receptors, trigger multiple signal transduction cascades that modulate central and peripheral cell functions. A fine balance between biosynthetic and degrading enzymes that control the right concentration of eCBs has been shown to provide neuroprotection in traumatic, ischemic, inflammatory and neurotoxic damage of the brain.

RESULTS

Since the existence of eCBs and their binding receptors was documented in the retina of numerous species (from fishes to primates), their involvement in the visual processing has been demonstrated, more recently with a focus on retinal neurodegeneration and neuroprotection.

CONCLUSION

The aim of this review is to present a modern view of the endocannabinoid system, in order to discuss in a better perspective available data from preclinical studies on the use of eCBs as new neuroprotective agents, potentially useful to prevent glaucoma and retinal neurodegenerative diseases.