Gene, Cell and Antibody-Based Therapies for the Treatment of Age-Related Macular Degeneration

Advances in the Study of Age-Related Macular Degeneration Based on Cell or Cell-Biomaterial Scaffolds

Age-related macular degeneration (AMD), a progressive neurodegenerative disorder affecting the central retina, is pathologically defined by the irreversible degeneration of photoreceptors and retinal pigment epithelium (RPE), coupled with extracellular drusen deposition and choroidal neovascularization (CNV), and AMD constitutes the predominant etiological factor for irreversible vision impairment in adults aged ≥60 years. Cell-based or cell-biomaterial scaffold-based approaches have been popular in recent years as a major research direction for AMD; monotherapy with cell-based approaches typically involves subretinal injection of progenitor-derived or stem cell-derived RPE cells to restore retinal homeostasis. Meanwhile, cell-biomaterial scaffolds delivered to the lesion site by vector transplantation have been widely developed, and the implanted cell-biomaterial scaffolds can promote the reintegration of cells at the lesion site and solve the problems of translocation and discrete cellular structure produced by cell injection. While these therapeutic strategies demonstrate preliminary efficacy, rigorous preclinical validation and clinical trials remain imperative to validate their long-term safety, functional durability, and therapeutic consistency. This review synthesizes current advancements and translational challenges in cell-based and cell-biomaterial scaffold approaches for AMD, aiming to inform future development of targeted interventions for AMD pathogenesis and management.

Anti-angiogenic biomolecules in neovascular age-related macular degeneration; therapeutics and drug delivery systems

Blindness in the elderly is often caused by age-related macular degeneration (AMD). The advanced type of AMD known as neovascular AMD (nAMD) has been linked to being the predominant cause of visual impairment in these people. Multiple neovascular structures including choroidal neovascular (CNV) membranes, fluid exudation, hemorrhages, and subretinal fibrosis, are diagnostic of nAMD. These pathological alterations ultimately lead to anatomical and visual loss. It is known that vascular endothelial growth factor (VEGF), a type of proangiogenic factor, mediates the pathological process underlying nAMD. Therefore, various therapies have evolved to directly target the disease. In this review article, an attempt has been made to discuss general explanations about this disease, all common treatment methods based on anti-VEGF drugs, and the use of drug delivery systems in the treatment of AMD. Initially, the pathophysiology, angiogenesis, and different types of AMD were described. Then we described current treatments and future treatment prospects for AMD and outlined the advantages and disadvantages of each. In this context, we first examined the types of therapeutic biomolecules and anti-VEGF drugs that are used in the treatment of AMD. These biomolecules include aptamers, monoclonal antibodies, small interfering RNAs, microRNAs, peptides, fusion proteins, nanobodies, and other therapeutic biomolecules. Finally, we described drug delivery systems based on liposomes, nanomicelles, nanoemulsions, nanoparticles, cyclodextrin, dendrimers, and composite vehicles that are used in AMD therapy.

Factors That Can Prolong Ocular Treatment Duration in Age-Related Macular Degeneration

Intravitreal injections of anti-vascular endothelial growth factor (VEGF) agents are used to treat wet age-related macular degeneration (wAMD); however, they are associated with a considerable treatment burden and poor real-world outcomes. The molecular size and charge of anti-VEGF agents influence drug pharmacokinetics in the vitreous and peak drug efficacy. This article reviews the established and novel strategies to prolong drug action, in the vitreal cavity, and thus reduce dosing frequency. Increased ocular residency can be attained by increasing drug size as with large molecules, such as KSI-301; adding polyethylene glycol to pegcetacoplan (APL-2) or avacincaptad pegol to increase molecular size; or binding to other targets that increase molecular size, such as vitreal albumin in the case of BI-X. Faricimab is a bispecific antibody in which the fragment crystallizable portion is engineered to prolong ocular residency and reduce systemic exposure. Conversely, small VEGF-binding molecules, such as brolucizumab, can be administered at higher clinical doses, with the potential for prolonged clinical activity versus larger molecules. Other important considerations include sustained drug delivery routes, such as the ranibizumab port delivery system or subconjunctival or suprachoroidal injection. More effective and longer-lasting treatments are needed for wAMD to prolong drug action and reduce dosing frequency. Several strategies are under investigation and the prevention of vision loss in patients with AMD or other retinal diseases may be attainable in the near future.

The function of p53 and its role in Alzheimer's and Parkinson's disease compared to age-related macular degeneration

The protein p53 is the main human tumor suppressor. Since its discovery, extensive research has been conducted, which led to the general assumption that the purview of p53 is also essential for additional functions, apart from the prevention of carcinogenesis. In response to cellular stress and DNA damages, p53 constitutes the key point for the induction of various regulatory processes, determining whether the cell induces cell cycle arrest and DNA repair mechanisms or otherwise cell death. As an implication, aberrations from its normal functioning can lead to pathogeneses. To this day, neurodegenerative diseases are considered difficult to treat, which arises from the fact that in general the underlying pathological mechanisms are not well understood. Current research on brain and retina-related neurodegenerative disorders suggests that p53 plays an essential role in the progression of these conditions as well. In this review, we therefore compare the role and similarities of the tumor suppressor protein p53 in the pathogenesis of Alzheimer's (AD) and Parkinson's disease (PD), two of the most prevalent neurological diseases, to the age-related macular degeneration (AMD) which is among the most common forms of retinal degeneration.

Secretory autophagy: a turn key for understanding AMD pathology and developing new therapeutic targets?

INTRODUCTION

Age-related macular degeneration (AMD) is an eye disease leading to vision loss with poorly known pathogenesis and limited therapeutic options. Degradative autophagy (DA) is impaired in AMD, but emerging evidence points to secretary autophagy (SA) as a key element in AMD pathogenesis.

AREAS COVERED

SA may cause the release of proteins and protein aggregates, lipofuscin, beta amyloid, faulty mitochondria, pro-inflammatory and pro-angiogenic factors from the retinal pigment epithelium (RPE) that may contribute to drusen formation and choroidal neovascularization. SA may replace DA, when formation of autolysosome is impaired, and then a harmful cargo, instead of being degraded, is extruded from the RPE contributing to drusen and/or angiogenic environment. Therefore, the interplay between DA and SA may be critical for drusen formation and choroidal neovascularization, so it can be a turn key to understand AMD pathogenesis.

EXPERT OPINION

Although SA fulfills some beneficial functions, it is detrimental for the retina in many cases. Therefore, inhibiting SA may be a therapeutic strategy in AMD, but it is challenged by the development of selective SA inhibitors that would not affect DA. The TRIM16, SEC22B and RAB8A proteins, specific for secretory autophagosome, may be primary candidates as therapeutic targets, but their action is not limited to autophagy and therefore requires further studies.

mTOR activity is essential for retinal pigment epithelium regeneration in zebrafish

The retinal pigment epithelium (RPE) plays numerous critical roles in maintaining vision and this is underscored by the prevalence of degenerative blinding diseases like age-related macular degeneration (AMD), in which visual impairment is caused by progressive loss of RPE cells. In contrast to mammals, zebrafish possess the ability to intrinsically regenerate a functional RPE layer after severe injury. The molecular underpinnings of this regenerative process remain largely unknown yet hold tremendous potential for developing treatment strategies to stimulate endogenous regeneration in the human eye. In this study, we demonstrate that the mTOR pathway is activated in RPE cells post-genetic ablation. Pharmacological and genetic inhibition of mTOR activity impaired RPE regeneration, while mTOR activation enhanced RPE recovery post-injury, demonstrating that mTOR activity is essential for RPE regeneration in zebrafish. RNA-seq of RPE isolated from mTOR-inhibited larvae identified a number of genes and pathways dependent on mTOR activity at early and late stages of regeneration; amongst these were components of the immune system, which is emerging as a key regulator of regenerative responses across various tissue and model systems. Our results identify crosstalk between macrophages/microglia and the RPE, wherein mTOR activity is required for recruitment of macrophages/microglia to the RPE injury site. Macrophages/microglia then reinforce mTOR activity in regenerating RPE cells. Interestingly, the function of macrophages/microglia in maintaining mTOR activity in the RPE appeared to be inflammation-independent. Taken together, these data identify mTOR activity as a key regulator of RPE regeneration and link the mTOR pathway to immune responses in facilitating RPE regeneration.

Novel approach to antiangiogenic factors in age-related macular degeneration therapy

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss among the population above 85 worldwide. There are two main types of AMD: neovascular and dry AMD. Neovascular AMD leads to macular changes resulting from abnormal choroidal neovascularization. Untreated neovascular AMD leads to scar formation and irreversible sight deterioration. Dry AMD in consequence leads to atrophic changes of the macula. The last decades brought a breakthrough in the therapy of neovascular age-related macular degeneration by introduction of, firstly, photodynamic therapy and, later, anti-VEGF agents administered intravitreally in order to stop neoangiogenesis. However, the treatment of dry AMD is still challenging. Among the directions in dry AMD treatment, the most promising are complement cascade inhibitors and complement cascade targeted gene therapy. In the article we outline the main directions in up-to-date experimental and practical approaches to wet and dry AMD therapy with the emphasis on antiangiogenic factors and gene therapy focused on the inhibition of pathological angiogenesis.

Complications Associated with Worse Visual Outcomes in Patients with Exudative Neovascular Age-Related Macular Degeneration

BACKGROUND

Neovascular age-related macular degeneration (AMD) represents a leading cause of vision loss in older subjects. The introduction of anti-vascular endothelial growth factor therapy has enormously improved the visual prognosis in these patients.

SUMMARY

However, severe complications may still occur in this disease and their development may significantly affect short- and long-term visual outcomes. Key Messages: In this article, we provided a review of these complications, highlighting their distinctive signs or symptoms and focusing on the current evidence of treatment. To place the complications related to neovascular AMD in a proper context, this review deals with core components essential for proper comprehension of neovascular AMD that includes pathogenesis, clinical signs, and basic principles of treatment.

Complement Inhibitors in Age-Related Macular Degeneration: A Potential Therapeutic Option

Age-related macular degeneration (AMD) is a multifactorial disease, which can culminate in irreversible vision loss and blindness in elderly. Nowadays, there is a big gap between dry AMD and wet AMD on treatment. Accounting for nearly 90% of AMD, dry AMD still lacks effective treatment. Numerous genetic and molecular researches have confirmed the significant role of the complement system in the pathogenesis of AMD, leading to a deeper exploration of complement inhibitors in the treatment of AMD. To date, at least 14 different complement inhibitors have been or are being explored in AMD in almost 40 clinical trials. While most complement inhibitors fail to treat AMD successfully, two of them are effective in inhibiting the rate of GA progression in phase II clinical trials, and both of them successfully entered phase III trials. Furthermore, recently emerging complement gene therapy and combination therapy also offer new opportunities to treat AMD in the future. In this review, we aim to introduce genetic and molecular associations between the complement system and AMD, provide the updated progress in complement inhibitors in AMD on clinical trials, and discuss the challenges and prospects of complement therapeutic strategies in AMD.

Network Pharmacology Analysis of Traditional Chinese Medicine Formula Shuang Di Shou Zhen Tablets Treating Nonexudative Age-Related Macular Degeneration

Objective

To analyze the pharmacological mechanism of the treatment of dry age-related macular degeneration (dry AMD) based on a network pharmacological approach of Shuang Di Shou Zhen Tablets (SDSZT) and to provide a new reference for the current lack of effective treatment of dry AMD.

Methods

The main chemical constituents and their targets of Rehmanniae Radix Praeparata, Ligustrum lucidum, Mori Fructus, Paeonia albiflora, Rhizoma Dioscoreae, Alisma orientale, Schisandra chinensis, Radix Polygoni Multiflori Preparata, Ophiopogon japonicus, and Radix Rehmanniae were obtained from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and Traditional Chinese Medicine Integrated Database (TCMID). The active ingredients of traditional Chinese medicine were screened according to Absorption, Distribution, Metabolism, and Excretion (ADME), the gene names of the targets of each active ingredient were obtained from the Uniprot database, the main targets of dry AMD were obtained from GeneCards and DisGeNET database, and the protein interaction analysis was performed on the String database. The Metascape database was used to analyze the “drug-component-target” and the biological processes and networks involved, and then, Cytoscape 3.8.1 was used to construct the “ SDSZT component-dry AMD target-pathway” network.

Results

The main active ingredients of SDSZT for dry AMD treatment are quercetin, kaempferol, luteolin, β-glutamine, β-carotene, etc. And, the core targets are RAC-alpha serine/threonine-protein kinase (AKT1), prostaglandin G/H synthase 1 (PTGS1), tumor necrosis factor (TNF), transcription factor AP-1 (JUN), apoptosis regulator Bcl-2 (BCL2), caspase-3 (CASP3), phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit gamma isoform (PIK3CG), androgen receptor (AR), apoptosis regulator BAX (BAX), etc. The biological pathways for the treatment of age-related macular degeneration by SDSZT mainly act on pathways in cancer, fluid shear stress and atherosclerosis, and TNF signaling pathway, and the main function of SDSZT is to regulate intracellular cytokine receptor binding.

Conclusion

This study initially reveals the multiconstituent, multitarget, and multipathway mechanism of action of SDSZT in the treatment of dry AMD and provides the basis for the clinical application of SDSZT.

Leukocyte Integrin Antagonists as a Novel Option to Treat Dry Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a complex multifactorial degenerative disease that leads to irreversible blindness. AMD affects the macula, the central part of the retina responsible for sharp central vision. Retinal pigment epithelium (RPE) is the main cellular type affected in dry AMD. RPE cells form a monolayer between the choroid and the neuroretina and are in close functional relationship with photoreceptors; moreover, RPE cells are part of the blood retina barrier that is disrupted in ocular diseases such as AMD. During ocular inflammation lymphocytes and macrophages are recruited, contact RPE and produce pro-inflammatory cytokines, which play an important role in AMD pathogenesis. The interaction between RPE and immune cells is mediated by leukocyte integrins, heterodimeric transmembrane receptors, and adhesion molecules, including VCAM-1 and ICAM-1. Within this frame, this study aimed to characterize RPE-leukocytes interaction and to investigate any potentially beneficial effects induced by integrin antagonists (DS-70, MN27 and SR714), developed in previous studies. ARPE-19 cells were co-cultured for different incubation times with Jurkat cells and apoptosis and necrosis levels were analyzed by flow cytometry. Moreover, we measured the mRNA levels of the pro-inflammatory cytokine IL-1β and the expression of adhesion molecules VCAM-1 and ICAM-1. We found that RPE-lymphocyte interaction increased apoptosis and necrosis levels in RPE cells and the expression of IL-1β. This interaction was mediated by the binding of α₄β₁ and α_Lβ₂ integrins to VCAM-1 and ICAM-1, respectively. The blockade of RPE-lymphocyte interaction with blocking antibodies highlighted the pivotal role played by integrins. Therefore, α₄β₁ and α_Lβ₂ integrin antagonists were employed to disrupt RPE-lymphocyte crosstalk. Small molecule integrin antagonists proved to be effective in reducing RPE cell death and expression of IL-1β, demonstrating that integrin antagonists could protect RPE cells from detrimental effects induced by the interaction with immune cells recruited to the retina. Overall, the leukocyte integrin antagonists employed in the present study may represent a novel opportunity to develop new drugs to fight dry AMD.

Age-Related Macular Degeneration: Role of Oxidative Stress and Blood Vessels

Age-related macular degeneration (AMD) is a common irreversible ocular disease characterized by vision impairment among older people. Many risk factors are related to AMD and interact with each other in its pathogenesis. Notably, oxidative stress and choroidal vascular dysfunction were suggested to be critically involved in AMD pathogenesis. In this review, we give an overview on the factors contributing to the pathophysiology of this multifactorial disease and discuss the role of reactive oxygen species and vascular function in more detail. Moreover, we give an overview on therapeutic strategies for patients suffering from AMD.

Self-Assembling Tacrolimus Nanomicelles for Retinal Drug Delivery

Neovascular age-related macular degeneration (AMD) is characterized by an increase in reactive oxygen species (ROS) and pro-inflammatory cytokines in the retinal pigment epithelium cells. The primary purpose of this study was the development of a clear, tacrolimus nanomicellar formulation (TAC-NMF) for AMD. The optimized formulation had a mean diameter of 15.41 nm, a zeta potential of 0.5 mV, and an entrapment efficiency of 97.13%. In-vitro cytotoxicity studies revealed the dose-dependent cytotoxicity of TAC-NMF on various ocular cell lines, such as human retinal pigment epithelium (D407), monkey retinal choroidal endothelial (RF/6A) cells, and human corneal epithelium (CCL 20.2) cells. Cellular uptake and in-vitro distribution studies using flow cytometry and confocal microscopy, respectively, indicated an elevated uptake of TAC-NMF in a time-dependent manner. Biocompatibility assay using macrophage RAW 264.7 cell line resulted in low production of inflammatory cytokines such as IL-6, IL-1β and TNF-α after treatment with TAC-NMF. There was a decrease in ROS in D407 cells pre-treated with sodium iodate (ROS inducing agent) after treating with TAC-NMF and tacrolimus drug. Similarly, there was a reduction in the pro-inflammatory cytokines and VEGF-A in D407 cells pretreated with sodium iodate. This indicates that TAC-NMF could lower pro-inflammatory cytokines and ROS commonly seen in AMD.