High drug payload nanoparticles formed from dexamethasone-peptide conjugates for the treatment of endotoxin-induced uveitis in rabbit

Fostering the unleashing potential of nanocarriers-mediated delivery of ocular therapeutics

Ocular delivery is the most challenging aspect in the field of pharmaceutical research. The major hurdle for the controlled delivery of drugs to the eye includes the physiological static barriers such as the complex layers of the cornea, sclera and retina which restrict the drug from permeating into the anterior and posterior segments of the eye. Recent years have witnessed inventions in the field of conventional and nanocarrier drug delivery which have shown considerable enhancement in delivering small to large molecules across the eye. The dynamic challenges associated with conventional systems include limited drug contact time and inadequate ocular bioavailability resulting from solution drainage, tear turnover, and dilution or lacrimation. To this end, various bioactive-based nanosized carriers including liposomes, ethosomes, niosomes, dendrimer, nanogel, nanofibers, contact lenses, nanoprobes, selenium nanobells, nanosponge, polymeric micelles, silver nanoparticles, and gold nanoparticles among others have been developed to circumvent the limitations associated with the conventional dosage forms. These nanocarriers have been shown to achieve enhanced drug permeation or retention and prolong drug release in the ocular tissue due to their better tissue adherence. The surface charge and the size of nanocarriers (10-1000 nm) are the important key factors to overcome ocular barriers. Various nanocarriers have been shown to deliver active therapeutic molecules including timolol maleate, ampicillin, natamycin, voriconazole, cyclosporine A, dexamethasone, moxifloxacin, and fluconazole among others for the treatment of anterior and posterior eye diseases. Taken together, in a nutshell, this extensive review provides a comprehensive perspective on the numerous facets of ocular drug delivery with a special focus on bioactive nanocarrier-based approaches, including the difficulties and constraints involved in the fabrication of nanocarriers. This also provides the detailed invention, applications, biodistribution and safety-toxicity of nanocarriers-based therapeutcis for the ophthalmic delivery.

Steroidal nanoformulations for the treatment of uveitis: potential, promises and future perspectives

BACKGROUND

Intraocular inflammation, commonly referred to as uveitis, is a prevalent ocular disease. The categorization of uveitis may be based on the prevailing anatomical site, which includes anterior, intermediate, and posterior uveitis. There exists a significant body of evidence indicating that T cells play a pivotal role in the pathogenesis of autoimmune uveitis. In addition to the presence of T cells, an elevation in levels of inflammatory cytokines and a reduction in regulatory cytokines were also noted. The primary pharmacological interventions for uveitis comprise of corticosteroids, methotrexate, anti-vascular endothelial growth factor (VEGF) agents, anti-tumor necrosis factor-alpha (TNF-α) antibodies, and sirolimus. These medications offer prompt alleviation for inflammation. Nevertheless, prolonged administration of corticosteroids invariably leads to unfavorable adverse reactions. The traditional topical corticosteroids exhibit certain limitations, including inadequate transcorneal permeation and low corneal retention, leading to reduced ocular bioavailability. Consequently, there is a growing inclination towards the creation of innovative steroid drug delivery systems with the aim of reducing the potential for adverse effects, while simultaneously enhancing the drug's corneal permeation and retention.

CONCLUSION

This review is an attempt to compile all the research work done so far in this field and provides a brief overview of the global efforts to develop innovative nanocarrier-based systems for corticosteroids.

Targeted dexamethasone nano-prodrug for corneal neovascularization management

BACKGROUND

To overcome the drawbacks of traditional therapy for corneal neovascularization (CNV), we evaluated the efficacy of polyethylene glycol (PEG)-conjugated Ala-Pro-Arg-Pro-Gly (APRPG) peptide modified dexamethasone (Dex), a novel nano-prodrug (Dex-PEG-APRPG, DPA).

METHODS

Characterization of DPA nano-prodrug were measured with transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses. Cytotoxicity and effects on cell migration and tube formation of DPA were evaluated in vitro. A murine CNV model was established by cornea alkali burn. The injured corneas were given eye drops of DPA (0.2 mM), Dex solution (0.2 mM), Dexp (2 mM), or normal saline three times a day. After two weeks, eyes were obtained for the analysis of histopathology, immunostaining, and mRNA expression.

RESULTS

DPA with an average diameter of 30 nm, presented little cytotoxicity and had good ocular biocompatibility. More importantly, DPA showed specific targeting to vascular endothelial cells with efficient inhibition on cell migration and tube formation. In a mouse CNV model, clinical, histological, and immunohistochemical examination results revealed DPA had a much stronger angiogenesis suppression than Dex, resembling a clinical drug with an order of magnitude higher concentration. This was ascribed to the significant downregulations in the expression of pro-angiogenic and pro-inflammatory factors in the corneas. In vivo imaging results also demonstrated that APRPG could prolong ocular retention time.

CONCLUSIONS

This study suggests that DPA nano-prodrug occupies advantages of specific targeting ability and improved bioavailability over conventional therapy, and holds great potential for safe and efficient CNV therapy.

Novel nanomicelle butenafine formulation for ocular drug delivery against fungal keratitis: In Vitro and In Vivo study

Fungal keratitis (FK) is a serious infectious corneal disease that leads to blindness. Butenafine (BTF) is an allylamine drug with high antifungal activity, but its poor water solubility and low bioavailability limit its clinical application in ophthalmology. To increase its aqueous solubility and corneal permeability, butenafine was encapsulated in d-ɑ-tocopheryl polyethylene glycol succinate (TPGS) polymeric nanomicelles to improve the bioavailability of the drug for the treatment of FK. Butenafine was successfully fabricated into nanomicelles with a high EE of 96.34 ± 1.65 % and DL of 6.71 ± 0.099 %. The BTF-NM showed an average particle size of 13.12 ± 0.24 nm, a zeta potential of -0.56 ± 0.44 mV and a narrow PDI of 0.12 ± 0.02 with a nearly spherical shape. The characterization results of FTIR, XRD and DSC indicated that BTF was encapsulated in the TPGS nanomicelles. The BTF-NM formulation also showed high storage stability, and the in vitro drug release study showed typical biphasic-release characteristics. In addition, the BTF-NM formulation displayed good cellular tolerance and excellent ocular tolerance in rabbits. Significantly elevated in vitro antifungal activity was also observed in the BTF-NM formulation, and remarkable improvements regarding in vivo corneal permeation were observed compared with the BTF suspension formulation. Finally, the in vivo antifungal activity studies indicated that the BTF-NM formulation had a good therapeutic effect on FK and had similar efficacy to that of commercial natamycin suspension eye drops. These results suggest that the BTF-NM ophthalmic formulation could be a promising ocular drug delivery system for the treatment of FK.

Next-generation nanomaterials: advancing ocular anti-inflammatory drug therapy

Ophthalmic inflammatory diseases, including conjunctivitis, keratitis, uveitis, scleritis, and related conditions, pose considerable challenges to effective management and treatment. This review article investigates the potential of advanced nanomaterials in revolutionizing ocular anti-inflammatory drug interventions. By conducting an exhaustive analysis of recent advancements and assessing the potential benefits and limitations, this review aims to identify promising avenues for future research and clinical applications. The review commences with a detailed exploration of various nanomaterial categories, such as liposomes, dendrimers, nanoparticles (NPs), and hydrogels, emphasizing their unique properties and capabilities for accurate drug delivery. Subsequently, we explore the etiology and pathophysiology of ophthalmic inflammatory disorders, highlighting the urgent necessity for innovative therapeutic strategies and examining recent preclinical and clinical investigations employing nanomaterial-based drug delivery systems. We discuss the advantages of these cutting-edge systems, such as biocompatibility, bioavailability, controlled release, and targeted delivery, alongside potential challenges, which encompass immunogenicity, toxicity, and regulatory hurdles. Furthermore, we emphasize the significance of interdisciplinary collaborations among material scientists, pharmacologists, and clinicians in expediting the translation of these breakthroughs from laboratory environments to clinical practice. In summary, this review accentuates the remarkable potential of advanced nanomaterials in redefining ocular anti-inflammatory drug therapy. We fervently support continued research and development in this rapidly evolving field to overcome existing barriers and improve patient outcomes for ophthalmic inflammatory disorders.

A New Era in Ocular Therapeutics: Advanced Drug Delivery Systems for Uveitis and Neuro-Ophthalmologic Conditions

The eye's intricate anatomical barriers pose significant challenges to the penetration, residence time, and bioavailability of topically applied medications, particularly in managing uveitis and neuro-ophthalmologic conditions. Addressing this issue, polymeric nano-based drug delivery systems (DDS) have surfaced as a promising solution. These systems enhance drug bioavailability in hard-to-reach target tissues, extend residence time within ocular tissues, and utilize biodegradable and nanosized polymers to reduce undesirable side effects. Thus, they have stimulated substantial interest in crafting innovative treatments for uveitis and neuro-ophthalmologic diseases. This review provides a comprehensive exploration of polymeric nano-based DDS used for managing these conditions. We discuss the present therapeutic hurdles posed by these diseases and explore the potential role of various biopolymers in broadening our treatment repertoire. Our study incorporates a detailed literature review of preclinical and clinical studies from 2017 to 2023. Owing to advancements in polymer science, ocular DDS has made rapid strides, showing tremendous potential to revolutionize the treatment of patients with uveitis and neuro-ophthalmologic disorders.

Polymer- and lipid-based nanocarriers for ocular drug delivery: Current status and future perspectives

Ocular diseases seriously affect patients' vision and life quality, with a global morbidity of over 43 million blindness. However, efficient drug delivery to treat ocular diseases, particularly intraocular disorders, remains a huge challenge due to multiple ocular barriers that significantly affect the ultimate therapeutic efficacy of drugs. Recent advances in nanocarrier technology offer a promising opportunity to overcome these barriers by providing enhanced penetration, increased retention, improved solubility, reduced toxicity, prolonged release, and targeted delivery of the loaded drug to the eyes. This review primarily provides an overview of the progress and contemporary applications of nanocarriers, mainly polymer- and lipid-based nanocarriers, in treating various eye diseases, highlighting their value in achieving efficient ocular drug delivery. Additionally, the review covers the ocular barriers and administration routes, as well as the prospective future developments and challenges in the field of nanocarriers for treating ocular diseases.

Immune modulating nanoparticles for the treatment of ocular diseases

Ocular diseases are increasingly influencing people’s quality of life. Complicated inflammatory mechanisms involved in the pathogenic process of ocular diseases make inflammation-targeting treatment a potential therapeutic approach. The limited efficacy of conventional anti-inflammatory therapeutic strategies, caused by various objective factors, such as complex ocular biological barriers, and subjective factors, such as poor compliance, are promoting the development of new therapeutic methods. With the advantages of considerable tissue permeability, a controllable drug release rate, and selective tissue targeting ability, nanoparticles have successfully captured researchers’ attention and have become a research hotspot in treating ocular diseases. This review will focus on the advantages of nanosystems over traditional therapy, the anti-inflammation mechanisms of nanoparticles, and the anti-inflammatory applications of nanoparticles in different ocular diseases (ocular surface diseases, vitreoretinopathy, uveal diseases, glaucoma, and visual pathway diseases). Furthermore, by analyzing the current situation of nanotherapy and the challenges encountered, we hope to inspire new ideas and incentives for designing nanoparticles more consistent with human physiological characteristics to make progress based on conventional treatments. Overall, some progress has been made in nanoparticles for the treatment of ocular diseases, and nanoparticles have rather broad future clinical translation prospects.

Synthesized nanoparticles, biomimetic nanoparticles and extracellular vesicles for treatment of autoimmune disease: Comparison and prospect

An emerging strategy is needed to treat autoimmune diseases, many of which are chronic with no definitive cure. Current treatments only alleviate symptoms and have many side effects affecting patient quality of life. Recently, nanoparticle drug delivery systems, an emerging method in medicine, has been used to target cells or organs, without damaging normal tissue. This approach has led to fewer side effects, along with a strong immunosuppressive capacity. Therefore, a nanotechnology approach may help to improve the treatment of autoimmune diseases. In this review, we separated nanoparticles into three categories: synthesized nanoparticles, biomimetic nanoparticles, and extracellular vesicles. This review firstly compares the typical mechanism of action of these three nanoparticle categories respectively in terms of active targeting, camouflage effect, and similarity to parent cells. Then their immunomodulation properties are discussed. Finally, the challenges faced by all these nanoparticles are described.

Application of Nanomaterials in the Treatment and Diagnosis of Ophthalmology Diseases

Eye diseases often lead to impaired vision and seriously affect the daily life of patients. Local administration of ophthalmic drugs is one of the most important approaches for the treatment of ophthalmic diseases. However, due to the special biochemical environment of the ocular tissue and the existence of many barriers, the bioavailability of conventional ophthalmic preparations in the eye is very low. Nanomaterials can be utilized as carriers of drugs, which can improve the absorption, distribution, metabolism and bioavailability of drugs in eyes. Nanomaterials have also the advantages of small size, simple preparation, good degradability, strong targeting, and little stimulation to biological tissues, providing an innovative and practical method for the drug delivery of ophthalmic diseases. In addition, nanomaterials can be used as an auxiliary means for early diagnosis of ophthalmic diseases by improving the specificity and accuracy of detection methods. Nanomaterials help clinicians and researchers delve deeper into the physiology and pathology of the eye at the nanoscale. We summarize the application of nanomaterials in the diagnosis and treatment of ophthalmic diseases in this review.

A Novel Indomethacin-Tripeptide Hydrogel for Inhibiting Ocular Inflammation

A highly efficient method for constructing indomethacin-peptide conjugates was developed using the natural amino acid tyrosine (Y) as the anchor for indomethacin (Idm). With pH = 6, Idm-YEE conjugate self-assembled in a low critical micelle concentration (CMC, 0.037 mg/mL) and formed a transparent hydrogel (0.4 wt%). The formed Idm-YEE hydrogel presented sustained drug release of indomethacin with a maximum of 40% during first 24 hours, which was superior to the reported Idm-containing supramolecular hydrogel systems. As kept at 4 °C, the Idm-YEE hydrogel showed good storage stability up to 30 days without obvious hydrolysis. As shown by MTT assay, the Idm-YEE hydrogel exhibited good cell compatibility against retinal pigment epithelial cells (ARPE-19) and Human corneal epithelial cells (HCEC). Ocular irritation test (i.e., clinical observations, fluorescein staining and H&E histological analysis) results showed good integrity of corneal architecture and no edema after Idm-YEE hydrogel treatment, which proved its good ocular biocompatibility. Besides, the LPS-stimulated levels of key inflammatory mediators, including NO, PGE₂ and IL-6, were greatly reduced by Idm-YEE hydrogel even in a low concentration (50 μM) in Raw264.7 cells, which indicated its comparable in vitro anti-inflammatory activity to indomethacin. Furthermore, the therapeutic efficacy of Idm-YEE hydrogel was evaluated in endotoxin-induced uveitis (EIU) rabbit model. By treating with dm-YEE hydrogel, the rabbit eyes had significantly lowered inflammation and exudation in the anterior chamber. The results of histological analysis, clinical score, inflammatory cell counts, aqueous protein concentration and immunohistochemical staining also demonstrated its good in vivo therapeutic activity towards ocular inflammation. Therefore, with good ocular biocompatibility and comparable anti-inflammatory effect towards ocular inflammation, the novel indomethacin-tripeptide hydrogel (Idm-YEE) developed in this work provides a potential treatment for anterior uveitis.

Dexamethasone Conjugates: Synthetic Approaches and Medical Prospects

Dexamethasone (DEX) is the most commonly prescribed glucocorticoid (GC) and has a wide spectrum of pharmacological activity. However, steroid drugs like DEX can have severe side effects on non-target organs. One strategy to reduce these side effects is to develop targeted systems with the controlled release by conjugation to polymeric carriers. This review describes the methods available for the synthesis of DEX conjugates (carbodiimide chemistry, solid-phase synthesis, reversible addition fragmentation-chain transfer [RAFT] polymerization, click reactions, and 2-iminothiolane chemistry) and perspectives for their medical application as GC drug or gene delivery systems for anti-tumor therapy. Additionally, the review focuses on the development of DEX conjugates with different physical-chemical properties as successful delivery systems in the target organs such as eye, joint, kidney, and others. Finally, polymer conjugates with improved transfection activity in which DEX is used as a vector for gene delivery in the cell nucleus have been described.

Modulation of Inflammatory Mediators by Polymeric Nanoparticles Loaded with Anti-Inflammatory Drugs

The first-line treatment of osteoarthritis is based on anti-inflammatory drugs, the most currently used being nonsteroidal anti-inflammatory drugs, selective cyclooxygenase 2 (COX-2) inhibitors and corticoids. Most of them present cytotoxicity and low bioavailability in physiological conditions, making necessary the administration of high drug concentrations causing several side effects. The goal of this work was to encapsulate three hydrophobic anti-inflammatory drugs of different natures (celecoxib, tenoxicam and dexamethasone) into core-shell terpolymer nanoparticles with potential applications in osteoarthritis. Nanoparticles presented hydrodynamic diameters between 110 and 130 nm and almost neutral surface charges (between −1 and −5 mV). Encapsulation efficiencies were highly dependent on the loaded drug and its water solubility, having higher values for celecoxib (39–72%) followed by tenoxicam (20–24%) and dexamethasone (14–26%). Nanoencapsulation reduced celecoxib and dexamethasone cytotoxicity in human articular chondrocytes and murine RAW264.7 macrophages. Moreover, the three loaded systems did not show cytotoxic effects in a wide range of concentrations. Celecoxib and dexamethasone-loaded nanoparticles reduced the release of different inflammatory mediators (NO, TNF-α, IL-1β, IL-6, PGE₂ and IL-10) by lipopolysaccharide (LPS)-stimulated RAW264.7. Tenoxicam-loaded nanoparticles reduced NO and PGE₂ production, although an overexpression of IL-1β, IL-6 and IL-10 was observed. Finally, all nanoparticles proved to be biocompatible in a subcutaneous injection model in rats. These findings suggest that these loaded nanoparticles could be suitable candidates for the treatment of inflammatory processes associated with osteoarthritis due to their demonstrated in vitro activity as regulators of inflammatory mediator production.

Sirolimus-Loaded Intravitreal Implant for Effective Treatment of Experimental Uveitis

Non-infectious uveitis, an ocular inflammatory condition that affects the iris, ciliary body, choroid, and adjacent tissues (retina, optic nerve, and vitreous), is an important cause of blindness worldwide. Sirolimus (SRL), a potent immunomodulatory drug, has shown promising results in the treatment of inflammatory ocular diseases. Despite this therapeutic potential, its clinical use is a major challenge due to low bioavailability and poor solubility. Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable polymer commonly used for ophthalmic drug delivery due to its suitable characteristics such as biocompatibility, good mechanical properties, and improvement of the pharmacokinetic profile of the drug. In the present study, we investigated the effects of SRL-PLGA implant on experimental autoimmune uveitis in rabbits. Clinical and histopathological examinations were performed, followed by assessment of protein levels and determination of myeloperoxidase (MPO) and N-acetylglucosaminidase (NAG) activity in the aqueous humor/vitreous. As a result, treated eyes had decreased average inflammatory scores, protein significant decreases in treated eyes, assessed after 35 days. Histopathological examination showed less severe intraocular inflammation and decreased tissue damage in treated eyes. According to these results, the SRL-PLGA implant evaluated in this study was apparently safe, reducing inflammation in treated eyes, with an extended effect possibly associated with prolonged release of SRL in the posterior segment of the eye. Therefore, intravitreal SRL-PLGA implant could be a promising alternative for treatment of non-infectious uveitis.

Steroid-Peptide Immunoconjugates for Attenuating T Cell Responses in an Experimental Autoimmune Encephalomyelitis Murine Model of Multiple Sclerosis

Diseases of immunity, including autoimmune diseases such as multiple sclerosis, transplantation graft rejection, allergy, and asthma, are prevalent and increasing in prevalence. They contribute to significant morbidity and mortality; however, few if any curative therapies exist, and those that are available lack either potency or specificity. Dendritic cells (DCs) are sentinels of the immune system that connect the innate and adaptive immune system and are critical regulators of both immunity and tolerance. We posited that the tolerogenic potential of DC could be harnessed to develop more specific and potent therapies for diseases of immunity by delivering autoantigen to a sufficient number of tolerogenic DCs in situ that could then inhibit pathogenic effector T cell responses. Specifically, we hypothesized that the steroid dexamethasone covalently coupled to a peptide antigen could be processed by DCs, induce tolerogenic DCs, and attenuate antigen-specific pathogenic T cell responses. To test this hypothesis, we synthesized a series of dexamethasone-peptide immunoconjugates by standard solid-phase peptide synthesis. The antigenic portion of the immunoconjugate could be presented by DCs, and the immunoconjugate induced a tolerogenic phenotype in DCs that then inhibited antigen-specific T cell proliferation in vitro. When the immunoconjugate was administered prophylactically in the murine experimental autoimmune encephalomyelitis model of multiple sclerosis, disease was attenuated compared to dexamethasone and peptide delivered as uncoupled components. Together, this work demonstrates the utility of immunoconjugates for inducing tolerance while establishing the foundation for future studies exploring methods to enrich and target DCs for tolerogenic therapies.

Glycol chitosan/oxidized hyaluronic acid hydrogel film for topical ocular delivery of dexamethasone and levofloxacin

In the present study, we fabricated a glycol chitosan/oxidized hyaluronic acid hydrogel film with promising potential for the dual ophthalmic delivery of dexamethasone (Dex) and levofloxacin (Lev). Utilizing different oxidation degrees of oxidized hyaluronic acid (OHA), several blank hydrogel films and Lev-loaded hydrogel films were successfully fabricated. With an increase in the oxidation degree of OHA, the swelling ratio of the hydrogel films decreased accordingly. The hydrogel films displayed a stepwise release of Lev and Dex, with Lev rapidly released from the hydrogel film, followed by a sustained release of Dex. Lev-loaded hydrogel films revealed a potent capacity to inhibit bacterial growth in different bacterial strains. In lipopolysaccharide-activated RAW264.7 macrophages, the formulated hydrogel films displayed potent in vitro anti-inflammatory activity by significantly downregulating various inflammatory cytokines. Overall, the fabricated hydrogel film acting as a dual drug delivery system might be a promising vehicle for the treatment of postoperative endophthalmitis.

Hydrogel eye drops as a non-invasive drug carrier for topical enhanced Adalimumab permeation and highly efficient uveitis treatment

Uveitis is one of the most popular blind-causing eye diseases worldwide. Adalimumab (ADA) is used for the uveitis treatment through systemic or intravitreal injection at the expense of systemic side effects and increased medical risks. Although eye drops, a non-invasive topical treatment, could be a potential strategy to reduce side effects, it remains challenging to apply due to limited bioavailability mainly linked to poor retention time and permeation capacity for eye biological barriers. Here, we reported hydrogel eye drops composed of low-deacetylated chitosan and β-glycerophosphate as an ADA carrier and tested its toxicity, tolerability, intraocular permeability, and efficacy of non-invasive treatment for uveitis. It's found the ADA-loaded hydrogel eye drops were more efficient than free ADA both in permeation rate and clinical efficacy for uveitis, Overall, this study provides a friendly non-invasive strategy to improve drug permeation rate and uveitis treatment efficacy, which may be valuable to clinically ophthalmic medication.