Effect of Diquafosol on Hyperosmotic Stress-induced Tumor Necrosis Factor-α and Interleukin-6 Expression in Human Corneal Epithelial Cells

Multifunctional Cerium Oxide Nanozyme for Synergistic Dry Eye Disease Therapy

Dry eye disease (DED) is a chronic multifactorial ocular surface disease mainly caused by the instability of tear film, characterized by a series of ocular discomforts and even visual disorders. Oxidative stress has been recognized as an upstream factor in DED development. Diquafosol sodium (DQS) is an agonist of the P2Y2 receptor to restore the integrity/stability of the tear film. With the ability to alternate between Ce3+ and Ce4+, cerium oxide nanozymes could scavenge overexpressed reactive oxygen species (ROS). Hence, a DQS-loaded cerium oxide nanozyme was designed to boost the synergistic treatment of DED. Cerium oxide with branched polyethylenimine-graft-poly(ethylene glycol) as nucleating agent and dispersant was fabricated followed with DQS immobilization via a dynamic phenylborate ester bond, obtaining the DQS-loaded cerium oxide nanozyme (defined as Ce@PBD). Because of the ability to mimic the cascade processes of superoxide dismutase and catalase, Ce@PBD could scavenge excessive accumulated ROS, showing strong antioxidant and anti-inflammatory properties. Meanwhile, the P2Y2 receptors in the conjunctival cells could be stimulated by DQS in Ce@PBD, which can relieve the incompleteness and instability of the tear film. The animal experiments demonstrated that Ce@PBD significantly restored the defect of the corneal epithelium and increased the number of goblet cells, with the promotion of tear secretion, which was the best among commercial DQS ophthalmic solutions.

Comparing two mucin secretagogues for the treatment of dry eye disease: a prospective randomized crossover trial

This study aimed to compare the clinical efficacy and investigate patients' preferences for two mucin secretagogues in the treatment of dry eye disease (DED). Thirty patients with DED were randomly treated with either 3% diquafosol or 2% rebamipide ophthalmic solution for 4 weeks, followed by an additional 4-week treatment using the other eye drop after a 2-week washout period. Objective and subjective assessments, including the corneal and conjunctival staining score, tear breakup time (TBUT), Schirmer 1 test, tear osmolarity, tear matrix metalloproteinase-9 (MMP-9), lipid layer thickness (LLT) and ocular surface disease index (OSDI), were performed at baseline, 4 weeks, 6 weeks, and 10 weeks. Patient preferences were assessed based on four categories (comfort, efficacy, convenience, willingness to continue) using a questionnaire and the overall subjective satisfaction score for each drug was obtained at the end of the trial. In total, 28 eyes from 28 patients were included in the analysis. Both diquafosol and rebamipide significantly improved the OSDI (p = 0.033 and 0.034, respectively), TBUT (p < 0.001 and 0.026, respectively), and corneal (p < 0.001 and 0.001, respectively) and conjunctival (p = 0.017 and 0.042, respectively) staining after 4 weeks of treatment. An increase in Schirmer test scores was observed only after rebamipide treatment (p = 0.007). No significant changes were detected in tear osmolarity, MMP-9, and LLT following both treatments. The patients' preference was slightly greater for diquafosol (46.4%) than rebamipide (36.7%), presumably due to rebamipide's bitter taste. The self-efficacy of both drugs and overall satisfaction scores were comparable. These findings indicate that two mucin secretagogues showed comparable effects in ameliorating symptoms and improving signs (TBUT, corneal and conjunctival staining) in patients with DED.

Protocol for a parallel assignment prospective, randomised, comparative trial to evaluate the safety and efficacy of intense pulsed light (IPL) combined with 3% diquafosol (DQS) ophthalmic solution in dry eye syndrome

INTRODUCTION

Evaporative dry eye (EDE) is common and can lead to ocular pain, decreased visual quality and reduced quality of life. Intense pulsed light (IPL) and 3% diquafosol ophthalmic solution have been found to be beneficial in reducing signs and symptoms of dry eye.

METHODS AND ANALYSIS

A randomised clinical trial will be performed at He Eye Specialist Hospital in Shenyang. 360 dry eye disease patients will be equally divided randomly into the IPL group, DQS group (3% diquafosol ophthalmic solution eye-drops) and IPL+group (IPL combined with 3% diquafosol eye-drops). All groups will be followed up for 4 weeks. The primary outcome measures will be the non-invasive tear break-up time and the Ocular Surface Disease Index change from the baseline. The secondary outcome measures willincludeconjunctival and cornea staining with fluorescein and lissamine, meibomian gland function and secretion quality, tear film lipid layer score, tear meniscus height, conjunctival hyperemia (redness score) changes . Adverse events also will be monitored and documented.

DISCUSSION

This study aimed to assess whether the combination of IPL with 3% diquafosol ophthalmic solution (study group), IPL+ (study group), is more effective than IPL (active control group) or DQS (active control group) in participants with EDE.

ETHICS AND DISSEMINATION

Management of dry eye with IPL combined with 3% diquafosol ophthalmic solution, registered on 23 January 2023. Ethics approval number: IRB (2022) K029.01. The study's findings will be shared regardless of the effect's direction.

TRIAL REGISTRATION NUMBER

NCT05694026.

The Role of Membrane-Tethered Mucins in Axial Epithelial Adhesion in Controlled Normal Stress Environments

The collective adhesive behavior of epithelial cell layers mediated by complex macromolecular fluid environments plays a vital role in many biological processes. Mucins, a family of highly glycosylated proteins, are known to lubricate cell-on-cell contacts in the shear direction. However, the role of mucins mediating axial epithelial adhesion in the direction perpendicular to the plane of the cell sheet has received less attention. This article subjects cell-on-cell layers of live ocular epithelia that express mucins on their apical surfaces to compression/decompression cycles and tensile loading using a customized instrument. In addition to providing compressive moduli of native cell-on-cell layers, it is found that the mucin layer between the epithelia acts as a soft cushion between the epithelial cell layers. Decompression experiments reveal mucin layers act as soft, nonlinear springs in the axial direction. The cell-on-cell layers withstand decompression before fracturing by a cohesive failure within the mucin layer. When mucin deficiency is induced via a protease treatment, it is found that the axial adhesion between the cell layers is increased. The findings which correlate changes in biological factors with changes in mechanical properties might be of interest to challenges in ophthalmology, vision care, and mucus research.

Combination therapy with 3% diquafosol tetrasodium ophthalmic solution and sodium hyaluronate: an effective therapy for patients with dry eye after femtosecond laser-assisted in situ keratomileusis

Purpose

To assess the effect of combination therapy with 3% diquafosol tetrasodium (DQS) and sodium hyaluronate (HA) for dry eye after femtosecond laser-assisted in situ keratomileusis (FS-LASIK).

Design

Prospective nonrandomized comparative trial.

Methods

The prospective study included 80 eyes of 40 patients who underwent FS-LASIK with or without preoperative dry eye. Patients were divided into a combination group and a HA group according to their willingness and the doctor's advice. The combination group was treated with DQS six times a day and HA four times a day, and the HA group was treated with HA four times a day after FS-LASIK. Ocular surface disease index (OSDI), ocular symptom score, vision-related score, environmental score, tear meniscus height (TMH), first non-invasive tear breakup time (NIBUT-First), average non-invasive tear breakup time (NIBUT-Ave), tear breakup time (TBUT), Schirmer I test (SIT), corneal fluorescein staining score (CFS), bulbar redness score, limbal redness score, lipid layer grade (LLG), meiboscore, lid margin abnormality, corneal sensitivity, and corneal nerve parameters were examined before surgery and at 1 week and 1 month after surgery. Surface regularity index (SRI) was also examined before surgery and at 1 month postoperatively.

Results

OSDI score (p = 0.024) and vision-related score (p = 0.026) were significantly lower in the combination group than in the HA group at 1 month after FS-LASIK, especially in patients with preoperative dry eye symptoms. The increasements of CFS (p = 0.018), bulbar redness score (p = 0.021), and limbal redness score (p = 0.009) were significantly lower in the combination group than in the HA group at 1 week after FS-LASIK. But other ocular surface parameters showed no difference between both groups at 1 week and 1 month after FS-LASIK. LLG was significantly higher in the combination group than in the HA group at 1 week (p = 0.004) and 1 month (p < 0.001) after surgery, especially in patients with high meiboscore. Additional DQS significantly improved corneal sensitivity in patients without preoperative dry eye symptoms at 1 month after FS-LASIK (p = 0.041).

Conclusion

The combination therapy with DQS and HA significantly relieved subjective symptoms, improved ocular surface status, and had the potential to promote corneal nerve growth in patients after FS-LASIK.

Diquafosol ophthalmic solution enhances mucin expression via ERK activation in human conjunctival epithelial cells with hyperosmotic stress

Purpose

To evaluate the effect of diquafosol tetrasodium on the expression of secretory and membrane-associated mucins in multi-layered cultures of primary human conjunctival epithelial cells (HCEC) using intracellular extracellular signal regulated kinase (ERK) signaling.

Methods

HCECs were treated with hyperosmotic stress (400 mOsm/l) for 24 h after air-liquid interface cell culture followed by treatment with diquafosol. HCECs were stimulated for 1 h with or without PD98059, an ERK inhibitor, then treated with diquafosol for 6 h and 24 h. Mucin 1 (MUC1), mucin 16 (MUC16), and MUC5AC mRNA and protein expression levels were analyzed, and cell viability was detected using an MTT assay. Western blot analysis was used to examine p44/42 MAPK (Erk1/2) and phosphorylated p44/42 MAPK (Erk1/2) expression.

Results

Hyperosmotic stressed HCECs demonstrated increased MUC5AC secretion and gene expression when treated with diquafosol. MUC1 mRNA levels increased significantly at 24 h (p<0.01), and expression of MUC16 mRNA levels increased at 6 h and were maintained until 24 h (p<0.05).There was no significant difference in cell viability compared to the control group. Immunostaining results for MUC1, MUC16, and MUC5AC in diquafosol tetrasodium-treated HCECs at 24 h showed more positive cells than in the control group. Phosphorylation of p44/42 MAPK (Erk1/2) signaling molecules significantly increased from 5 min to 60 min (p<0.05). The effects of diquafosol on mucin expressions in hyperosmotic stressed HCECs were significantly inhibited by PD98059, an ERK inhibitor, at 6 h and 24 h.

Conclusions

ERK signaling may regulate the expression levels of MUC1, MUC16, and MUC5AC induced by diquafosol in hyperosmotic stressed HCECs.

Efficacy of Artificial Tears Based on an Extract of Artemia salina Containing Dinucleotides in a Rabbit Dry Eye Model

(1) Background: Artemia salina is a brine shrimp containing high concentrations of dinucleotides, molecules with properties for dry eye treatment. For this reason, the purpose of the study was to evaluate the effect of the artificial tears based on an extract of Artemia salina in a rabbit dry eye model. (2) Methods: A prospective and randomized study was carried out. Twenty rabbits were divided into 4 groups (n = 5, each group): healthy rabbits, dry eye rabbits, dry eye rabbits treated with hypromellose (HPMC), and dry eye rabbits treated with Artemia salina. Dry eye was induced by the topical instillation of 0.2% benzalkonium chloride. The measurements were performed before and after the treatment for 5 consecutive days. (3) Results: The topical instillation of artificial tears containing Artemia salina showed beneficial effects on tear secretion, tear break-up time, corneal staining, the density of Goblet cells, heigh of mucin cloud secreted by these cells, and mRNA levels of IL-1β and MMP9 in conjunctival cells. Compared with the HPMC, there was a statistically significant improvement (p < 0.05) with the Artemia salina in all the variables under study, except for the conjunctival hyperemia, density of Goblet cells, and mRNA levels of IL-6. (4) Conclusions: The potential of artificial tears based on Artemia salina as a secretagogue agent for dry eye treatment was confirmed, opening the door for future clinical trials and studies to extrapolate the findings for dry eye patients.