Poly(lactic-co-glycolic acid) Nanoparticles Encapsulating the Prenylated Flavonoid, Xanthohumol, Protect Corneal Epithelial Cells from Dry Eye Disease-Associated Oxidative Stress

Attenuation of neutrophil adhesion and formation of neutrophil extracellular traps by pooled human immune globulins

Introduction

This study investigated the efficacy of pooled human immune globulins (Flebogamma® DIF) to combat the formation of neutrophil extracellular traps (NETs) and NETosis, along with neutrophil adhesion to corneal epithelial cells in response to dry eye disease relevant stimuli.

Methods

Human neutrophils were isolated by bead-based immunomagnetic depletion of non-target cells from human whole blood. NETosis was induced using phorbol 12-myristate 13-acetate (PMA) or anti-citrullinated histone 4 R3 antibody (H4R3 ACPA). Extracellular DNA was used as a surrogate biomarker of NETosis, and it was quantified using a 96-well, plate reader-based fluorescent assay and by confocal microscopy in 8-well chambers using the DNA dye, SYTOXTM Green. Neutrophils were labeled with calcein-AM and adhesion to human corneal epithelial cells was measured. The efficacy of a dose-range of pooled human immune globulin (Flebogamma® DIF, 0.01%-5%) was tested in all assays.

Results

Pooled human immune globulins (Flebogamma® DIF) dose-dependently inhibited both PMA and H4R3 ACPA induced NETosis, with concentrations ≥2.5% fully preventing release of extracellular DNA over a 2-16 h time period. Similarly, Flebogamma® 5% DIF prevented NETosis against PMA (20 nM) and a dose range (0.1-10 μg/mL) of H4R3 ACPA. Both PMA and H4R3 ACPA increased adhesion of neutrophils to corneal epithelial cells by 20% and 5%, respectively. Flebogamma® DIF treatment resulted in a dose-dependent reduction of neutrophil adhesion, with Flebogamma® 5% DIF reducing adhesion to baseline levels.

Discussion

These findings show the dose-dependent efficacy of pooled human immune globulins, specifically Flebogamma® DIF against experimentally and pathologically induced NETosis and neutrophil adhesion to corneal epithelial cells, in vitro. The results from this study support the continued clinical development of Flebogamma® 5% DIF as a novel and efficacious treatment for the signs and symptoms of dry eye disease.

Synergistic Proliferation Effects of Xanthohumol and Niflumic Acid on Merkel and Glioblastoma Cancer Cells: Role of Cell Membrane Interactions

The objective of our research was to determine the effects of xanthohumol (XN), a flavonoid isolated from hops (Humulus lupulus), and the anti-inflammatory drug niflumic acid (NA), separately and in combination with each other, on the proliferation of human cancer cells. Additionally, so as to understand the mechanism underlying the anticancer properties of the tested compounds, their effects on the biophysical parameters of a model membrane were assessed. The cells were incubated with XN and NA at various concentrations, either individually or in combination with each other. Cell proliferation was quantified using the sulforodamine B (SRB) assay. In addition, the IC50 values for niflumic acid and xanthohumol applied separately were determined by cell proliferation tests for the following human cancer cell lines: 5637 (urinary bladder carcinoma), A-431 (epidermoid carcinoma), UM-SCC-17A (head and neck squamous carcinoma), SK-MEL-3 (melanoma), MCC13 (Merkel cell cancer), and A172 (glioblastoma), in comparison with the mouse normal fibroblasts (BALB/3T3 clone A31). The results show that the two-compound combinations of XN and NA significantly decreased the proliferation of cancer cells in a dose-dependent manner, and the effects were stronger than the additive responses to XN and NA individually. The membrane studies revealed a synergistic effect on the membrane rigidity when using the mixture of XN and NA, which may explain the observed increase in anticancer activity for the combined XN and NA. Our results suggest that NSAIDs, such as niflumic acid, may be a promising strategy for co-application with xanthohumol as anticancer drugs.

PLL-g-PEG Polymer Inhibits Antibody-Drug Conjugate Uptake into Human Corneal Epithelial Cells In Vitro

Purpose: Antibody-drug conjugates (ADCs) are a relatively recent advance in the delivery of chemotherapeutics that improve targeting of cytotoxic agents. However, despite their antitumor activity, severe ocular adverse effects, including vision loss, have been reported for several ADCs. The nonspecific uptake of ADCs into human corneal epithelial cells (HCECs) and their precursors via macropinocytosis has been proposed to be the primary mechanism of ocular toxicity. In this study, we evaluated the ability of a novel polymer, poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), to decrease the ADC rituximab-mc monomethylauristatin F (MMAF) (RIX) uptake into human corneal epithelial (HCE-T) cells. Methods: HCE-T cells were exposed to increasing concentrations of RIX to determine inhibition of cell proliferation. HCE-T cells were treated with PLL-g-PEG, the macropinocytosis inhibitor 5-(N-ethyl-N-isopropyl) amiloride (EIPA), or vehicle. After 30 min of incubation, RIX was added. ADC was detected by fluorescent anti-human immunoglobulin G and fluorescently conjugated dextran as viewed by microscopy. Results: RIX caused dose-dependent inhibition of HCE-T cell proliferation. EIPA significantly reduced RIX uptake and decreased macropinocytosis as assessed by direct quantification of RIX using a fluorescently conjugated anti-human antibody as well as quantification of macropinocytosis using fluorescently conjugated dextran. PLL-g-PEG resulted in a dose-dependent inhibition of RIX uptake with half-maximal inhibitory concentrations of 0.022%-0.023% PLL-g-PEG. Conclusion: The data show PLL-g-PEG to be a potent inhibitor of RIX uptake by corneal epithelial cells and support its use as a novel therapeutic approach for the prevention of ocular adverse events associated with ADC therapy.

Nanomedicines for Dry Eye Syndrome: Targeting Oxidative Stress with Modern Nanomaterial Strategies

Dry eye syndrome (DES) is a dynamic, chronic disease of the ocular surface and ocular appendages caused by inflammation. The most common symptoms include redness, itching, and blurred vision, resulting from dysfunction of the meibomian glands and impaired tear-film production. Factors contributing to the development of DES include environmental elements, such as UV radiation, and internal elements, such as hormonal imbalances. These factors increase oxidative stress, which exacerbates inflammation on the surface of the eye and accelerates the development of DES. In recent years, the incidence of DES has risen, leading to a greater need to develop effective treatments. Current treatments for dry eye are limited and primarily focus on alleviating individual symptoms, such as reducing inflammation of the ocular surface. However, it is crucial to understand the pathomechanism of the disease and tailor treatment to address the underlying causes to achieve the best possible therapeutic outcomes. Therefore, in this review, we analyzed the impact of oxidative stress on the development of DES to gain a better understanding of its pathomechanism and examined recently developed nanosystems that allow drugs to be delivered directly to the disease site.

The mechanisms of natural products for eye disorders by targeting mitochondrial dysfunction

The human eye is susceptible to various disorders that affect its structure or function, including glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). Mitochondrial dysfunction has been identified as a critical factor in the pathogenesis and progression of eye disorders, making it a potential therapeutic target in the clinic. Natural products have been used in traditional medicine for centuries and continue to play a significant role in modern drug development and clinical therapeutics. Recently, there has been a surge in research exploring the efficacy of natural products in treating eye disorders and their underlying physiological mechanisms. This review aims to discuss the involvement of mitochondrial dysfunction in eye disorders and summarize the recent advances in the application of natural products targeting mitochondria. In addition, we describe the future perspective and challenges in the development of mitochondria-targeting natural products.

Oxidative stress in the eye and its role in the pathophysiology of ocular diseases

Oxidative stress occurs through an imbalance between the generation of reactive oxygen species (ROS) and the antioxidant defense mechanisms of cells. The eye is particularly exposed to oxidative stress because of its permanent exposure to light and due to several structures having high metabolic activities. The anterior part of the eye is highly exposed to ultraviolet (UV) radiation and possesses a complex antioxidant defense system to protect the retina from UV radiation. The posterior part of the eye exhibits high metabolic rates and oxygen consumption leading subsequently to a high production rate of ROS. Furthermore, inflammation, aging, genetic factors, and environmental pollution, are all elements promoting ROS generation and impairing antioxidant defense mechanisms and thereby representing risk factors leading to oxidative stress. An abnormal redox status was shown to be involved in the pathophysiology of various ocular diseases in the anterior and posterior segment of the eye. In this review, we aim to summarize the mechanisms of oxidative stress in ocular diseases to provide an updated understanding on the pathogenesis of common diseases affecting the ocular surface, the lens, the retina, and the optic nerve. Moreover, we discuss potential therapeutic approaches aimed at reducing oxidative stress in this context.

Dynamics of Organic Acids during the Droplet-Vitrification Cryopreservation Procedure Can Be a Signature of Oxidative Stress in Pogostemon yatabeanus

Cryopreservation in liquid nitrogen (LN, -196 °C) is a unique option for the long-term conservation of threatened plant species with non-orthodox or limitedly available seeds. In previous studies, a systematic approach was used to develop a droplet-vitrification (DV) cryopreservation protocol for Postemon yatabeanus shoot tips that includes preculture with 10% sucrose, osmoprotection with C4-35%, cryoprotection with A3-80% vitrification solution, and a three-step regrowth starting with the ammonium-free medium. The tricarboxylic acid (TCA) cycle is a crucial component of plant cell metabolism as it is involved in redox state regulation and energy provision. We hypothesized that organic acids (OAs) associated with the TCA and its side reactions indirectly indicate metabolism intensity and oxidative stress development in shoot tips under the cryopreservation procedure. In this study, the contents of 14 OAs were analyzed using gas chromatography-tandem mass spectrometry (GC-MS/MS) in P. yatabeanus shoot tips in a series of treatments including individual steps of the DV procedure, additional stress imposed by non-optimum protocol conditions (no preculture, no osmoprotection, various vitrification solution composition, using vials instead of aluminum foils, etc.) and regrowth on different media with or without ammonium or growth regulators. The possible relation of OA content with the total cryoprotectant (CPA) concentration and shoot tips regeneration percentage was also explored. Regeneration of cryopreserved shoot tips reduced in descending order as follows: standard protocol condition (91%) > non-optimum vitrification solution (ca. 68%) > non-optimum preculture (60-62%) > regrowth medium (40-64%) > no osmoprotection, cryopreservation in vials (28-30%). Five OAs (glycolic, malic, citric, malonic, and lactic) were the most abundant in the fresh (control) shoot tips. The dynamic pattern of OAs during the DV procedure highly correlated (r = 0.951) with the total CPA concentration employed: it gradually increased through the preculture, osmoprotection, and cryoprotection, peaked at cooling/rewarming (6.38-fold above control level), and returned to the fresh control level after 5 days of regrowth (0.89-fold). The contents of four OAs (2-hydroxybutyric, 3-hydroxypropionic, lactic, and glycolic) showed the most significant (10-209-fold) increase at the cooling/rewarming step. Lactic and glycolic acids were the major OAs at cooling/rewarming, accounting for 81% of the total OAs content. The OAs were categorized into three groups based on their dynamics during the cryopreservation protocol, and these groups were differently affected by protocol step modifications. However, there was no straightforward relationship between the dynamics of OAs and shoot tip regeneration. The results suggest that active modulation of OAs metabolism may help shoot tips to cope with osmotic stress and the chemical cytotoxicity\ of CPAs. Further intensive studies are needed to investigate the effect of cryopreservation on cell primarily metabolism and identify oxidative stress-related biomarkers in plant materials.

Use of Poly Lactic-co-glycolic Acid Nano and Micro Particles in the Delivery of Drugs Modulating Different Phases of Inflammation

Chronic inflammation contributes to the pathogenesis of many diseases, including apparently unrelated conditions such as metabolic disorders, cardiovascular diseases, neurodegenerative diseases, osteoporosis, and tumors, but the use of conventional anti-inflammatory drugs to treat these diseases is generally not very effective given their adverse effects. In addition, some alternative anti-inflammatory medications, such as many natural compounds, have scarce solubility and stability, which are associated with low bioavailability. Therefore, encapsulation within nanoparticles (NPs) may represent an effective strategy to enhance the pharmacological properties of these bioactive molecules, and poly lactic-co-glycolic acid (PLGA) NPs have been widely used because of their high biocompatibility and biodegradability and possibility to finely tune erosion time, hydrophilic/hydrophobic nature, and mechanical properties by acting on the polymer's composition and preparation technique. Many studies have been focused on the use of PLGA-NPs to deliver immunosuppressive treatments for autoimmune and allergic diseases or to elicit protective immune responses, such as in vaccination and cancer immunotherapy. By contrast, this review is focused on the use of PLGA NPs in preclinical in vivo models of other diseases in which a key role is played by chronic inflammation or unbalance between the protective and reparative phases of inflammation, with a particular focus on intestinal bowel disease; cardiovascular, neurodegenerative, osteoarticular, and ocular diseases; and wound healing.

Dietary Alcohol Consumption Elicits Corneal Toxicity Through the Generation of Cellular Oxidative Stress

Purpose: Clinical data suggest that alcohol use is associated with the development of signs and symptoms of dry eye disease. However, preclinical data investigating ocular toxicity after dietary alcohol consumption are lacking. In this study, we investigated the effects of alcohol on the ocular surface, in human corneal epithelial cells (HCE-T) in vitro and in C57BL/6JRj mice in vivo. Methods: HCE-T were exposed to clinically relevant doses of ethanol. To determine the effects of dietary alcohol consumption in vivo, wild-type mice were administered the Lieber-DeCarli liquid diet (5% vol/vol ethanol or isocaloric control) for 10 days ad libitum. Corneal fluorescein staining was performed to assess ocular surface damage. Histopathological and gene expression studies were performed on cornea and lacrimal gland tissue. Results: Sublethal doses of ethanol (0.01%-0.5%) resulted in a dose-dependent increase of cellular oxidative stress in corneal epithelial cells and a significant increase in NFE2L2 and downstream antioxidant gene expression, as well as an increase in NFκB signaling; short-term exposure (0.5%, 4 h) triggered significant corneal epithelial cell barrier breakdown. Exposure to the alcohol-containing diet caused a 3-fold increase in corneal fluorescein staining, with no effect on tear volumes. Corneal thickness was significantly reduced in the alcohol diet group, and corneal tissue revealed dysregulated antioxidant and NFκB signaling. Our data provide the first published evidence that alcohol exposure causes ocular toxicity in mice. Conclusions: Our results are consistent with clinical studies linking past alcohol consumption to signs of ocular surface disease.

Fluorescent Nanosystems for Drug Tracking and Theranostics: Recent Applications in the Ocular Field

The greatest challenge associated with topical drug delivery for the treatment of diseases affecting the posterior segment of the eye is to overcome the poor bioavailability of the carried molecules. Nanomedicine offers the possibility to overcome obstacles related to physiological mechanisms and ocular barriers by exploiting different ocular routes. Functionalization of nanosystems by fluorescent probes could be a useful strategy to understand the pathway taken by nanocarriers into the ocular globe and to improve the desired targeting accuracy. The application of fluorescence to decorate nanocarrier surfaces or the encapsulation of fluorophore molecules makes the nanosystems a light probe useful in the landscape of diagnostics and theranostics. In this review, a state of the art on ocular routes of administration is reported, with a focus on pathways undertaken after topical application. Numerous studies are reported in the first section, confirming that the use of fluorescent within nanoparticles is already spread for tracking and biodistribution studies. The first section presents fluorescent molecules used for tracking nanosystems’ cellular internalization and permeation of ocular tissues; discussions on the classification of nanosystems according to their nature (lipid-based, polymer-based, metallic-based and protein-based) follows. The following sections are dedicated to diagnostic and theranostic uses, respectively, which represent an innovation in the ocular field obtained by combining dual goals in a single administration system. For its great potential, this application of fluorescent nanoparticles would experience a great development in the near future. Finally, a brief overview is dedicated to the use of fluorescent markers in clinical trials and the market in the ocular field.

Topical Porphyrin Antioxidant Protects Against Ocular Surface Pathology in a Novel Rabbit Model for Particulate Matter-Induced Dry Eye Disease

Purpose: Particulate matter (PM) is a primary cause for the development of acute and chronic dry eye disease, especially irritant-induced conjunctivitis. The purpose of the present study was to determine the effects of fine atmospheric PM on the rabbit ocular surface, and determine the protective effects of a synthetic antioxidant, manganese(III) tetrakis(1-methyl-4-pyridyl) porphyrin (Mn-TM-2-PyP), in vitro and in vivo. Methods: Rabbit corneal epithelial cells (SIRC) were exposed to increasing concentrations of PM to determine the effects on cell motility and viability. The in vivo effects of topically instilled PM were tested in New Zealand White rabbits. Comprehensive ophthalmic exams and corneal fluorescein staining were performed. Results: Exposure to PM resulted in dose-dependent cell death and impaired cellular motility; Mn-TM-2-PyP protected against PM-induced cytotoxicity and significantly increased SIRC cell motility. In vivo, exposure to PM (5 mg/ml, topical, 3 times daily for 7 days) resulted in signs of dry eye, notably hyperemia, increased corneal fluorescein staining, and decreased tear volumes. Mn-TM-2-PyP significantly improved hyperemia and corneal fluorescein readouts but had no effect on tear production. Lifitegrast (Xiidra^®) showed similar pharmacologic efficacy to Mn-TM-2-PyP. Conclusion: Overall, these data provide evidence that PM induces phenotypes of ocular surface disease responsive to antioxidant and immunosuppressant therapy. To our knowledge this is the first report of a large animal model to study PM-induced ocular surface disease. The present work provides standardized experimental paradigms for the comprehensive in vitro and in vivo testing of novel therapeutic approaches targeting PM-induced conjunctivitis and dry-eye.

Nanotechnology for Topical Drug Delivery to the Anterior Segment of the Eye

Topical drug delivery is one of the most challenging aspects of eye therapy. Eye drops are the most prevalent drug form, especially for widely distributed anterior segment eye diseases (cataracts, glaucoma, dry eye syndrome, inflammatory diseases, etc.), because they are convenient and easy to apply by patients. However, conventional drug formulations are usually characterized by short retention time in the tear film, insufficient contact with epithelium, fast elimination, and difficulties in overcoming ocular tissue barriers. Not more than 5% of the total drug dose administered in eye drops reaches the interior ocular tissues. To overcome the ocular drug delivery barriers and improve drug bioavailability, various conventional and novel drug delivery systems have been developed. Among these, nanosize carriers are the most attractive. The review is focused on the different drug carriers, such as synthetic and natural polymers, as well as inorganic carriers, with special attention to nanoparticles and nanomicelles. Studies in vitro and in vivo have demonstrated that new formulations could help to improve the bioavailability of the drugs, provide sustained drug release, enhance and prolong their therapeutic action. Promising results were obtained with drug-loaded nanoparticles included in in situ gel.

Evaluation of the Antitumour and Antiproliferative Effect of Xanthohumol-Loaded PLGA Nanoparticles on Melanoma

Cutaneous melanoma is the deadliest type of skin cancer and current treatment is still inadequate, with low patient survival rates. The polyphenol xanthohumol has been shown to inhibit tumourigenesis and metastasization, however its physicochemical properties restrict its application. In this work, we developed PLGA nanoparticles encapsulating xanthohumol and tested its antiproliferative, antitumour, and migration effect on B16F10, malignant cutaneous melanoma, and RAW 264.7, macrophagic, mouse cell lines. PLGA nanoparticles had a size of 312 ± 41 nm and a PdI of 0.259, while achieving a xanthohumol loading of about 90%. The viability study showed similar cytoxicity between the xanthohumol and xanthohumol-loaded PLGA nanoparticles at 48 h with the IC50 established at 10 µM. Similar antimigration effects were observed for free and the encapsulated xanthohumol. It was also observed that the M1 antitumor phenotype was stimulated on macrophages. The ultimate anti-melanoma effect emerges from an association between the viability, migration and macrophagic phenotype modulation. These results display the remarkable antitumour effect of the xanthohumol-loaded PLGA nanoparticles and are the first advance towards the application of a nanoformulation to deliver xanthohumol to reduce adverse effects by currently employed chemotherapeutics.