Effects of Eye Drops Containing Hyaluronic Acid-Nimesulide Conjugates in a Benzalkonium Chloride-Induced Experimental Dry Eye Rabbit Model

Implications of nanotechnology for the treatment of Dry Eye Disease: Recent advances

Managing Dry Eye Disease (DED), a prevalent condition affecting the ocular surface, remains challenging despite advancements in diagnostics and therapies. Current treatments primarily involve lubricating eye drops and anti-inflammatory medications, which often require prolonged use and generally provide only symptomatic relief. The current study focuses on improving DED treatments through nano-drug delivery technologies and advanced formulations. These systems aim to address the limitations of conventional therapies by providing extended, targeted, and sustained drug release. The development of innovative nanomaterials offers improved precision, control, and customization for DED management. By enabling controlled and sustained drug release, these nano-drug delivery systems could offer longer-lasting relief, addressing the chronic nature of DED more effectively than current symptomatic therapies. Future research should focus on integrating multiple therapeutic agents within these systems to simultaneously target inflammation and tear film instability. This review examines the potential of nano-based materials for DED treatment, with a particular emphasis on lipid-based, polymer-based and polysaccharide-based systems.

Hyaluronic acid conjugates with controlled oleic acid substitution as new nanomaterials for improving ocular co-delivery of cyclosporine A and oleic acid

A structural conjugate (HOC) of polysaccharide, hyaluronic acid (HA) with different ratios of oleic acid (OA) via cystamine (CYS) linker as a new ocular biomaterial was developed. The HOCs with controlled degrees of substitution of OA (4.6 %, 8.3 % and 12.2 %) were synthesized to form self-assembled HA-CYS-OA nanoparticles (HONs, HON1, HON2, HON3). A poorly water-soluble cyclosporine A (CsA) to be used for the treatment of multifactorial dry eye disease (DED) was chosen as model drug. CsA-loaded HONs exhibited improved solution transparency via solubilizing capacity of HON, and increased in vitro drug permeation compared to Restasis®. The physicochemical properties of CsA-loaded HONs such as nano behaviors, solution transparency, drug release, drug permeation and ocular cytocompatibility were highly variable according to the ratios of OA substitution. Interestingly, this CsA-loaded HON1 as optimal ocular nanoformulation showed markedly augmented macrophage polarization into the M2 phenotype, downregulated the expression of proinflammatory cytokines levels in LPS-induced M1 macrophage, and effectively inhibited VEGF-induced endothelial cell proliferation and capillary-like tube formation by the synergistic effect of CsA and HON1 containing OA at the same time. Collectively, the current fatty acid conjugated to HA, named fattigation platform, providing the roles and physicochemical properties via structural features of HA could be a promising co-delivery strategy of drug and fatty acid for DED and other ophthalmic disease treatments.

Curcumin/pEGCG-encapsulated nanoparticles enhance spinal cord injury recovery by regulating CD74 to alleviate oxidative stress and inflammation

Spinal cord injury (SCI) often accompanies impairment of motor function, yet there is currently no highly effective treatment method specifically for this condition. Oxidative stress and inflammation are pivotal factors contributing to severe neurological deficits after SCI. In this study, a type of curcumin (Cur) nanoparticle (HA-CurNPs) was developed to address this challenge by alleviating oxidative stress and inflammation. Through non-covalent interactions, curcumin (Cur) and poly (-)-epigallocatechin-3-gallate (pEGCG) are co-encapsulated within hyaluronic acid (HA), resulting in nanoparticles termed HA-CurNPs. These nanoparticles gradually release curcumin and pEGCG at the SCI site. The released pEGCG and curcumin not only scavenge reactive oxygen species (ROS) and prevents apoptosis, thereby improving the neuronal microenvironment, but also regulate CD74 to promote microglial polarization toward an M2 phenotype, and inhibits M1 polarization, thereby suppressing the inflammatory response and fostering neuronal regeneration. Moreover, in vivo experiments on SCI mice demonstrate that HA-CurNPs effectively protect neuronal cells and myelin, reduce glial scar formation, thereby facilitating the repair of damaged spinal cord tissues, restoring electrical signaling at the injury site, and improving motor functions. Overall, this study demonstrates that HA-CurNPs significantly reduce oxidative stress and inflammation following SCI, markedly improving motor function in SCI mice. This provides a promising therapeutic approach for the treatment of SCI.

Prostaglandin E2 may clinically alleviate dry eye disease by inducing Th17 cell differentiation

Dry eye (DE) is a multifactorial ocular surface disease characterised by an imbalance in tear homeostasis. The pathogenesis of DE is complex and related to environmental, immunological (e.g., T helper 17 cells) and other factors. However, the DE disease pathogenesis remains unclear, thereby affecting its clinical treatment. This study aimed to explore the mechanism through which prostaglandin E2 (PGE2) affects DE inflammation by regulating Th17. The DE mouse model was established through subcutaneous injection of scopolamine hydrobromide. The tear secretion test and break-up time (BUT) method were used to detect tear secretion and tear film BUT, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to detect the concentrations of PGE2, interleukin (IL)-17, IL-6 and tumour necrosis factor (TNF-α) in tear fluid and those of PGE2 and IL-17 in the serum. RT-qPCR and western blotting were used to test the mRNA and protein expression levels of IL-17 and retinoid-related orphan receptor-γt (RORγt). PGE2 was highly expressed in the DE mouse model. The mRNA and protein levels of IL-17 and the key Th17 transcription factor RORγt were increased in tissues of the DE mice. Moreover, PGE2 promoted tear secretion, reduced the BUT, increased the IL-17 concentration in tears and increased the Th17 cell proportion in DE, whereas the PGE2 receptor inhibitor AH6809 reversed the effects of PGE2 on tear secretion, BUT, and the Th17 cell proportion in draining lymph node (DLN) cells. Taken together, the study findings indicate that PGE2 could induce DE-related symptoms by promoting Th17 differentiation.

Development of triamcinolone acetonide-hyaluronic acid conjugates with selective targeting and less osteoporosis effect for rheumatoid arthritis treatments

Rheumatoid arthritis (RA) is a common systemic autoimmune disease in developed countries. In clinical treatment, steroids have been used as bridging and adjunctive therapy after disease-modifying anti-rheumatic drug administration. However, the severe side effects caused by the nonspecific targeting of organs followed by long-term administration have limited their usage in RA. In this study, poorly water-soluble triamcinolone acetonide (TA), a highly potent corticosteroid for intra-articular injection, is conjugated on hyaluronic acid (HA) for intravenous purposes with increased specific drug accumulation in inflamed parts for RA. Our results demonstrate that the designed HA/TA coupling reaction reveals >98 % conjugation efficiency in the dimethyl sulfoxide/water system, and the resulting HA-TA conjugates show lower osteoblastic apoptosis compared with that in free TA-treated osteoblast-like NIH3T3 cells. Furthermore, in a collagen-antibody-induced arthritis animal study, HA-TA conjugates enhanced the initiative targeting ability to inflame tissue and reduce the histopathological arthritic changes (score = 0). Additionally, the level of bone formation marker P1NP in HA-TA-treated ovariectomized mice (303.6 ± 40.6 pg/mL) is significantly higher than that in the free TA-treated group (143.1 ± 3.9 pg/mL), indicating the potential for osteoporotic reduction using an efficient HA conjugation strategy for the long-term administration of steroids against RA.

Thermoresponsive in-situ gel containing hyaluronic acid and indomethacin for the treatment of corneal chemical burn

Ocular chemical burns are prevalent injuries that must have immediate and effective treatment to avoid complications. Aiming to improve bioavailability and efficacy, a poloxamer-based thermoresponsive in-situ gelling system containing hyaluronic acid and indomethacin was developed. Formulations with different polymeric proportions were screened through rheological measurements resulting in an optimized system (F2) with gelling temperature of 34.2 ± 0.11 °C. Its maximum viscosity varied from 77.33 mPa (25 °C) to 82.95 mPa (34 °C) following a non-Newtonian profile and a pH of 6.86 ± 0.01. No incompatibilities were found after infrared analysis. Polarized light microscopy and cryo-transmission electron microscopy have demonstrated micelles of nano-sized dimensions (21.86 nm) with indomethacin entrapped in the core, forming a polymeric network under heating. In vitro tests revealed a cumulative release of 59.75 ± 3.17 % up to 24 h under a sustained release profile. Results from HET-CAM assay indicated that F2 was well tolerated. Corneal wound healing was significantly faster in animals treated with F2 compared to a commercial formulation and an untreated group. These findings suggests that F2 could be an efficient system to delivery drugs into the ocular surface improving wound healing.

Antifungal Combination Eye Drops for Fungal Keratitis Treatment

Fungal keratitis (FK) is a corneal mycotic infection that can lead to vision loss. Furthermore, the severity of FK is aggravated by the emergence of resistant fungal species. There is currently only one FDA-approved formulation for FK treatment forcing hospital pharmacy departments to reformulate intravenous drug preparations with unknown ocular bioavailability and toxicity. In the present study, natamycin/voriconazole formulations were developed and characterized to improve natamycin solubility, permanence, and safety. The solubility of natamycin was studied in the presence of two cyclodextrins: HPβCD and HPγCD. The HPβCD was chosen based on the solubility results. Natamycin/cyclodextrin (HPβCD) inclusion complexes characterization and a competition study between natamycin and voriconazole were conducted by NMR (Nuclear Magnetic Resonance). Based on these results, several eye drops with different polymer compositions were developed and subsequently characterized. Permeability studies suggested that the formulations improved the passage of natamycin through the cornea compared to the commercial formulation Natacyn^®. The ocular safety of the formulations was determined by BCOP and HET-CAM. The antifungal activity assay demonstrated the ability of our formulations to inhibit the in vitro growth of different fungal species. All these results concluded that the formulations developed in the present study could significantly improve the treatment of FK.

A new antioxidant made from a pterostilbene functionalized graphene nanocomposite as an efficient treatment for dry eye disease

Dry eye disease is a common condition that affects the eyes. It is caused by problems with the tear film and the tear dynamics. Dry eye can be caused by an increase in the amount of reactive oxygen species (ROS) in the corneal epithelium. The treatment for dry eye typically focuses on relieving the uncomfortable symptoms by using eye drops such as artificial tears, antibiotics, and by using anti-inflammatory/immunosuppressive agents such as cyclosporine, and lifitegrast. However, the recovery of patients with dry eye can take several years particularly if the symptoms are severe. This is because the present treatment approaches for dry eye are not based on its cause, e.g., the oxidative stress arising from the rapid increase in ROS. This work describes a new type of antioxidant made from pterostilbene (PS) and carboxyl-chitosan modified graphene (CG). The use of a hydrophilic two-dimensional CG nanosheet to improve the properties of PS is reported. Superior enhanced properties including better cellular permeability, long sustained release period (over 30 h), and antioxidant properties, were realized by using PS-CG. A hyperosmotic (HS) damaged human corneal epithelial cell (HCEC) model was used for antioxidant tests. This model has an intracellular ROS level 4 times more than that of a control group. The ROS content was declined efficiently to the same amount as normal cells in the PS-CG treated HS group. There was a significant decline in the content of lactate dehydrogenase (LDH) and the apoptosis rate of HCEC in the PS-CG treated HS group when compared to that seen in the HS model. Real-time polymerase chain reaction (PCR) and western blots (WB) were used to understand the antioxidant mechanism of PS-CG. The results showed that the antioxidant was working by activating the Keap1-Nrf2-ARE signalling pathway. In vivo testing testing using a dry eye mouse model suggested that the PS-CG acted as an efficient antioxidant. More tear production and healthier corneal and conjunctival epithelial cells were achieved when PC-CG was applied to this model. The use of PS-CG could be a new strategy for treating dry eye and other ocular diseases caused by ROS.

Hyaluronic Acid: Its Versatile Use in Ocular Drug Delivery with a Specific Focus on Hyaluronic Acid-Based Polyelectrolyte Complexes

Extensive research is currently being conducted into novel ocular drug delivery systems (ODDS) that are capable of surpassing the limitations associated with conventional intraocular anterior and posterior segment treatments. Nanoformulations, including those synthesised from the natural, hydrophilic glycosaminoglycan, hyaluronic acid (HA), have gained significant traction due to their enhanced intraocular permeation, longer retention times, high physiological stability, inherent biocompatibility, and biodegradability. However, conventional nanoformulation preparation methods often require large volumes of organic solvent, chemical cross-linkers, and surfactants, which can pose significant toxicity risks. We present a comprehensive, critical review of the use of HA in the field of ophthalmology and ocular drug delivery, with a discussion of the physicochemical and biological properties of HA that render it a suitable excipient for drug delivery to both the anterior and posterior segments of the eye. The pivotal focus of this review is a discussion of the formation of HA-based nanoparticles via polyelectrolyte complexation, a mild method of preparation driven primarily by electrostatic interaction between opposing polyelectrolytes. To the best of our knowledge, despite the growing number of publications centred around the development of HA-based polyelectrolyte complexes (HA-PECs) for ocular drug delivery, no review articles have been published in this area. This review aims to bridge the identified gap in the literature by (1) reviewing recent advances in the area of HA-PECs for anterior and posterior ODD, (2) describing the mechanism and thermodynamics of polyelectrolyte complexation, and (3) critically evaluating the intrinsic and extrinsic formulation parameters that must be considered when designing HA-PECs for ocular application.

Controlled Fabrication of Bioactive Microtubes for Screening Anti-Tongue Squamous Cell Migration Drugs

The treatment of tongue squamous cell carcinoma (TSCC) faces challenges because TSCC has an aggressive biological behavior and manifests usually as widespread metastatic disease. Therefore, it is particularly important to screen out and develop drugs that inhibit tumor invasion and metastasis. Two-dimensional (2D) cell culture has been used as in vitro models to study cellular biological behavior, but growing evidence now shows that the 2D systems can result in cell bioactivities that deviate appreciably the in vivo response. It is urgent to develop a novel 3D cell migration model in vitro to simulate the tumor microenvironment as much as possible and screen out effective anti-migration drugs. Sodium alginate, has a widely used cell encapsulation material, as significant advantages. We have designed a microfluidic device to fabricate a hollow alginate hydrogel microtube model. Based on the difference in liquid flow rate, TSCC cells (Cal27) were able to be evenly distributed in the hollow microtubes, which was confirmed though fluorescence microscope and laser scanning confocal microscope (LSCM). Our microfluidic device was cheap, and commercially available and could be assembled in a modular way, which are composed of a coaxial needle, silicone hose, and syringes. It was proved that the cells grow well in artificial microtubes with extracellular matrix (ECM) proteins by LSCM and flow cytometry. Periodic motility conferred a different motor state to the cells in the microtubes, more closely resembling the environment in vivo. The quantitative analysis of tumor cell migration could be achieved simply by determining the position of the cell in the microtube cross-section. We verified the anti-migration effects of three NSAIDs drugs (aspirin, indomethacin, and nimesulide) with artificial microtubes, obtaining the same results as conventional migration experiments. The results showed that among the three NSAIDs, nimesulide showed great anti-migration potential against TSCC cells. Our method holds great potential for application in the more efficient screening of anti-migration tumor drugs.