Novel Thiol Containing Hybrid Antioxidant-Nitric Oxide Donor Small Molecules for Treatment of Glaucoma

Chitosan-Rapamycin Carbon Dots Alleviate Glaucomatous Retinal Injury by Inducing Autophagy to Promote M2 Microglial Polarization

Introduction

Glaucoma is a prevalent cause of irreversible vision impairment, characterized by progressive retinal ganglion cells (RGCs) loss, with no currently available effective treatment. Rapamycin (RAPA), an autophagy inducer, has been reported to treat glaucoma in rodent models by promoting RGC survival, but its limited water solubility, systemic toxicity, and pre-treatment requirements hinder its potential clinical applications.

Methods

Chitosan (CS)-RAPA carbon dot (CRCD) was synthesized via hydrothermal carbonization of CS and RAPA and characterized by transmission electron microscopy, Fourier transform infrared spectra, and proton nuclear magnetic resonance. In vitro assays on human umbilical cord vein endothelial and rat retinal cell line examined its biocompatibility and anti-oxidative capabilities, while lipopolysaccharide-stimulated murine microglia (BV2) assays measured its effects on microglial polarization. In vivo, using a mouse retinal ischemia/reperfusion (I/R) model by acute intraocular pressure elevation, the effects of CRCD on visual function, RGC apoptosis, oxidative stress, and M2 microglial polarization were examined.

Results

CRCD exhibited good water solubility and anti-oxidative capabilities, in the form of free radical scavenging. In vitro, CRCD was bio-compatible and lowered oxidative stress, which was also found in vivo in the retinal I/R model. Additionally, both in vitro with lipopolysaccharide-stimulated BV2 cells and in vivo with the I/R model, CRCD was able to promote M2 microglial polarization by activating autophagy, which, in turn, down-regulated pro-inflammatory cytokines, such as IL-1β and TNF-α, as well as up-regulated anti-inflammatory cytokines, such as IL-4 and TGF-β. All these anti-oxidative and anti-inflammatory effects ultimately aided in preserving RGCs, and subsequently, improved visual function.

Discussion

CRCD could serve as a potential novel treatment strategy for glaucoma, via incorporating RAPA into CDs, in turn not only mitigating its toxic side effects but also enhancing its therapeutic efficacy.

Future directions of glaucoma treatment: emerging gene, neuroprotection, nanomedicine, stem cell, and vascular therapies

PURPOSE OF REVIEW

The aim of this article is to summarize current research on novel gene, stem cell, neuroprotective, nanomedicine, and vascular therapies for glaucoma.

RECENT FINDINGS

Gene therapy using viral vectors and siRNA have been shown to reduce intraocular pressure by altering outflow and production of aqueous humor, to reduce postsurgical fibrosis with few adverse effects, and to increase retinal ganglion cell (RGC) survival in animal studies. Stem cells may treat glaucoma by replacing or stimulating proliferation of trabecular meshwork cells, thus restoring outflow facility. Stem cells can also serve a neuroprotective effect by differentiating into RGCs or preventing RGC loss via secretion of growth factors. Other developing neuroprotective glaucoma treatments which can prevent RGC death include nicotinamide, the NT-501 implant which secretes ciliary neurotrophic factor, and a Fas-L inhibitor which are now being tested in clinical trials. Recent studies on vascular therapy for glaucoma have focused on the ability of Rho Kinase inhibitors and dronabinol to increase ocular blood flow.

SUMMARY

Many novel stem cell, gene, neuroprotective, nanomedicine, and vascular therapies have shown promise in preclinical studies, but further clinical trials are needed to demonstrate safety and efficacy in human glaucomatous eyes. Although likely many years off, future glaucoma therapy may take a multifaceted approach.

The Role and Mechanism of Nicotinamide Riboside in Oxidative Damage and a Fibrosis Model of Trabecular Meshwork Cells

Purpose

To investigate the potential effects and mechanism of nicotinamide riboside (NR) on the oxidative stress and fibrosis model of human trabecular meshwork (HTM) cell line cells.

Methods

HTM cells were pretreated with NR, followed by the induction of oxidative injury and fibrosis by hydrogen peroxide (H2O2) and TGF-β2, respectively. Cell viability was tested using Hoechst staining and MTT assays, cell proliferation was assessed by EdU assay, and cell apoptosis was detected by flow cytometry and western blotting. DCFH-DA and DHE probes were used to measure the level of reactive oxygen species (ROS), and MitoTracker staining was used to measure the mitochondrial membrane potential (MMP). Fibrotic responses, including cell migration and deposition of extracellular matrix (ECM) proteins, were detected via Transwell assays, qRT-PCR, and immunoblotting.

Results

NR pretreatment improved the viability, proliferation, and MMP of H2O2-treated HTM cells. Compared to cells treated solely with H2O2, HTM cells treated with both NR and H2O2, exhibited a reduced rate of apoptosis and generation of ROS. Compared with H2O2 pretreatment, NR pretreatment upregulated expression of the JAK2/Stat3 pathway but inhibited mitogen-activated protein kinase (MAPK) pathway expression. Moreover, 10-ng/mL TGF-β2 promoted cell proliferation and migration, which were inhibited by NR pretreatment. Both qRT-PCR and immunoblotting showed that NR inhibited the expression of fibronectin in a TGF-β2-induced fibrosis model.

Conclusions

NR has a protective effect on oxidative stress and fibrosis in HTM cells, which may be related to the JAK2/Stat3 pathway and MAPK pathway.

Translational Relevance

Our research provides the ongoing data for potential therapy of NAD+ precursors in glaucoma.

Neuroprotective and Anti-Inflammatory Activities of Hybrid Small-Molecule SA-10 in Ischemia/Reperfusion-Induced Retinal Neuronal Injury Models

Embolism, hyperglycemia, high intraocular pressure-induced increased reactive oxygen species (ROS) production, and microglial activation result in endothelial/retinal ganglion cell death. Here, we conducted in vitro and in vivo ischemia/reperfusion (I/R) efficacy studies of a hybrid antioxidant-nitric oxide donor small molecule, SA-10, to assess its therapeutic potential for ocular stroke.

METHODS

To induce I/R injury and inflammation, we subjected R28 and primary microglial cells to oxygen glucose deprivation (OGD) for 6 h in vitro or treated these cells with a cocktail of TNF-α, IL-1β and IFN-γ for 1 h, followed by the addition of SA-10 (10 µM). Inhibition of microglial activation, ROS scavenging, cytoprotective and anti-inflammatory activities were measured. In vivo I/R-injured mouse retinas were treated with either PBS or SA-10 (2%) intravitreally, and pattern electroretinogram (ERG), spectral-domain optical coherence tomography, flash ERG and retinal immunocytochemistry were performed.

RESULTS

SA-10 significantly inhibited microglial activation and inflammation in vitro. Compared to the control, the compound SA-10 significantly attenuated cell death in both microglia (43% vs. 13%) and R28 cells (52% vs. 17%), decreased ROS (38% vs. 68%) production in retinal microglia cells, preserved neural retinal function and increased SOD1 in mouse eyes.

CONCLUSION

SA-10 is protective to retinal neurons by decreasing oxidative stress and inflammatory cytokines.

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

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

Nanomaterial-based ophthalmic drug delivery

The low bioavailability and side effects of conventional drugs for eye disease necessitate the development of efficient drug delivery systems. Accompanying the developments of nanofabrication techniques, nanomaterials have been recognized as promising tools to overcome these challenges due to their flexible and programmable properties. Given the advances achieved in material science, a broad spectrum of functional nanomaterials capable of overcoming various ocular anterior and posterior segment barriers have been explored to satisfy the demands for ocular drug delivery. In this review, we first highlight the unique functions of nanomaterials suitable for carrying and transporting ocular drugs. Then, various functionalization strategies are emphasized to endow nanomaterials with superior performance in enhanced ophthalmic drug delivery. The rational design of several affecting factors is essential for ideal nanomaterial candidates and is depicted as well. Lastly, we introduce the current applications of nanomaterial-based delivery systems in the therapy of different ocular anterior and posterior segment diseases. The limitations of these delivery systems as well as potential solutions are also discussed. This work will inspire innovative design thinking for the development of nanotechnology-mediated strategies for advanced drug delivery and treatment toward ocular diseases.

Modulation of Mitochondrial Metabolic Parameters and Antioxidant Enzymes in Healthy and Glaucomatous Trabecular Meshwork Cells with Hybrid Small Molecule SA-2

Oxidative stress (OS)-induced mitochondrial damage is a risk factor for primary open-angle glaucoma (POAG). Mitochondria-targeted novel antioxidant therapies could unearth promising drug candidates for the management of POAG. Previously, our dual-acting hybrid molecule SA-2 with nitric oxide-donating and antioxidant activity reduced intraocular pressure and improved aqueous humor outflow in rodent eyes. Here, we examined the mechanistic role of SA-2 in trabecular meshwork (TM) cells in vitro and measured the activity of intracellular antioxidant enzymes during OS. Primary human TM cells isolated from normal (hNTM) or glaucomatous (hGTM) post-mortem donors and transformed glaucomatous TM cells (GTM-3) were used for in vitro assays. We examined the effect of SA-2 on oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) in vitro using Seahorse Analyzer with or without the oxidant, tert-butyl hydroperoxide (TBHP) treatment. Concentrations of total antioxidant enzymes, catalase (CAT), malondialdehyde (MDA), and glutathione peroxidase (GPx) were measured. We observed significant protection of both hNTM and hGTM cells from TBHP-induced cell death by SA-2. Antioxidant enzymes were elevated in SA-2-treated cells compared to TBHP-treated cells. In addition, SA-2 demonstrated an increase in mitochondrial metabolic parameters. Altogether, SA-2 protected both normal and glaucomatous TM cells from OS via increasing mitochondrial energy parameters and the activity of antioxidant enzymes.

Review on potential effects of traditional Chinese medicine on glaucoma

ETHNIC PHARMACOLOGICAL RELEVANCE

Glaucoma is the second most common blindness in the world, which seriously affects the life quality of patients. Traditional Chinese Medicines (TCM), are important plant materials, widely used for ocular disease all over the world. With the help of modern ophthalmic detection technology, TCM has gradually become an important content in the field of ophthalmology, characterized by more targets and lower toxicity.

AIM OF THIS REVIEW

This review presents an overview of the pathogenesis of glaucoma in both modern and traditional medicines, and summarizes the therapeutic effect of TCM on glaucoma including their formula, crude drugs and active components, and also the application of acupuncture.

METHODS

A collection and collation of relevant scientific articles from different scientific databases was performed regarding TCM and its application on glaucoma. The therapeutic effects of TCM were summarized and analyzed according to the existing experimental and clinical researches, while the GSE26299 database were employed to screen bioinformatics analysis of glaucoma based on the GEO database chip.

RESULTS

There were many positive signs showing that TCM could increase the survival rate of retinal ganglion cells, which may be related to its regulation of microcirculation, oxidative stress, and the immune system. Hence, TCM plays an active role in treating glaucoma. In addition, the bioinformatics analysis predicted that the pathogenesis of glaucoma might be related to p53, MAPK, NF-κB signal, as well as other pathways by KEGG analysis, and the results from bioinformatics analysis predicted that PIK3R6, FGF1, and TYRP1 etc. CONCLUSION: TCM exerts definite effects on preventing and treating ocular disease. It could alleviate and treat glaucoma in various ways. The differentiation syndrome should thus be taken as the basis to propose appropriate treatment options of TCM making their application on glaucoma more popular.

Nano-based eye drop: Topical and noninvasive therapy for ocular diseases

Eye drops are the most accessible therapy for ocular diseases, while inevitably suffering from their lower bioavailability which highly restricts the treatment efficacy. The introduction of nanotechnology has attracted considerable interest as it has advantages over conventional ones such as prolonged ocular surface retention time and enhanced ocular barrier penetrating properties, and achieving higher bioavailability and improved treatment efficacy. This review describes various ocular diseases treated with eye drops as well as the physiological and anatomical ocular barriers faced with through drug administration. It also summarizes the recent advances regarding the utilization of nanotechnology in developing eye drops, and how to optimize the nanocarrier-based ocular drug delivery systems. The prospective future research directions for nano-based eye drops are also discussed here.

Efficacy and safety of netarsudil/latanoprost fixed-dose combination vs. monotherapy in open-angle glaucoma or ocular hypertension: A systematic review and meta-analysis of randomized controlled trials

Objective

As monotherapy is insufficient for some patients, the existing fixed-dose combination (FDC) requires two or more daily administrations with declining adherence. The present study compared the efficacy and safety of netarsudil/latanoprost FDC with monotherapy of its individual components in patients with glaucoma.

Methods

A systematic literature search was performed for studies comparing netarsudil/latanoprost fixed-dose combination (FDC) vs. monotherapy in patients with glaucoma. The primary endpoints included intraocular pressure (IOP), intraocular pressure reduction percentage (IOPR%) and adverse events (AEs).

Results

Three randomized controlled trial studies (RCTs) involving 1,692 patients (FDC: 556, netarsudil: 577, latanoprost: 559) were included in this meta-analysis. FDC was more effective than netarsudil, with significantly lower diurnal IOP over three time points (8:00 a.m., 10:00 a.m., 4:00 p.m.), mean diurnal IOP (MD = −2.36 [−3.08, −1.63], P < 0.00001) and higher IOPR% (MD = 9.60 [7.86, 11.33], P < 0.00001). When comparing FDC with latanoprost, both mean diurnal IOP (MD = −1.64 [−2.05, −1.23], P < 0.00001) and diurnal IOP across 3 time points were significantly lower with FDC than with latanoprost, while FDC induced significantly higher IOPR% (MD = 6.09 [4.40, 7.77], P < 0.00001). Incidence of total AEs was similar between netarsudil and FDC, but higher with FDC than with latanoprost.

Conclusion

Netarsudil/latanoprost FDC appears to be superior to netarsudil or latanoprost alone, with better ocular hypotensive effects. However, there are concerns that netarsudil/latanoprost FDC was associated with a significantly higher incidence of AEs specifically compared with latanoprost.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=311956.

Nanoparticles in ocular applications and their potential toxicity

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

Restoring the oxidative balance in age-related diseases - An approach in glaucoma

As human life expectancy increases, age-related health issues including neurodegenerative diseases continue to rise. Regardless of genetic or environmental factors, many neurodegenerative conditions share common pathological mechanisms, such as oxidative stress, a hallmark of many age-related health burdens. In this review, we describe oxidative damage and mitochondrial dysfunction in glaucoma, an age-related neurodegenerative eye disease affecting 80 million people worldwide. We consider therapeutic approaches used to counteract oxidative stress in glaucoma, including untapped treatment options such as novel plant-derived antioxidant compounds that can reduce oxidative stress and prevent neuronal loss. We summarize the current pre-clinical models and clinical work exploring the therapeutic potential of a range of candidate plant-derived antioxidant compounds. Finally, we explore advances in drug delivery systems, particular those employing nanotechnology-based carriers which hold significant promise as a carrier for antioxidants to treat age-related disease, thus reviewing the key current state of all of the aspects required towards translation.

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

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

Nano encapsulated novel compound SA-10 with therapeutic activity in both acute and chronic murine hindlimb ischemia models

The production dysregulation of reactive oxygen species (ROS) and nitric oxide (NO) in ischemic tissues results in endothelial dysfunction, hyperinflammation and poor blood circulation. Here, we report a hybrid molecule, SA-10 with both NO donating and ROS scavenging abilities that demonstrated potent cytoprotection and tube formation activity in endothelial cells under H₂O₂-induced oxidative stress. SA-10 loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (SA-10 NPs) were delivered intramuscularly (IM) to two murine hindlimb ischemia models. In the acute mode ischemia/reperfusion (I/R), the muscle damage, hyperinflammation, and lung edema were significantly reduced 3 days post-dose while in the chronic ischemia model, significant improvement of blood perfusion and physical endurance was observed over 30 days (P < 0.05). Elderly patients with acute and chronic limb ischemia have limited options for surgical or endovascular interventions, so we anticipate that a product like SA-10 NPs has potential as one of the therapeutic alternatives to surgery.