Recent Developments About the Pathogenesis of Dry Eye Disease: Based on Immune Inflammatory Mechanisms

Tear Global Metabolomic Differences in Pre-Operative Cataract Patients With and Without Dry Eye Disease

PURPOSE

The primary aim of this article was to investigate differences in the metabolomic profile of tear fluid obtained from pre-operative cataract patients, with or without dry eye disease. The objective was to look for metabolomic signatures that might discriminate between the two groups.

METHODS

A total of 222 patients were enrolled in the study. Eighty-one were randomly selected for metabolomic analysis from both dry eye positive and dry eye negative groups, categorized prior to cataract surgery. Tear film was collected using Schirmer-1 strips and analyzed using an optimized method developed for low-volume Schirmer samples and allowing for repeated analyses, including other -omics approaches at a later stage. Metabolomic data were collected using a global liquid chromatography-mass spectrometry method. Samples were compared using principal component analysis and volcano plots to look for overall global differences as well as group-specific metabolic signatures.

RESULTS

All samples were analyzed with a high number of features identified. No group-specific clustering was observed in principal component analysis for the dry eye positive or dry eye negative groups. However, volcano plots revealed that a majority of the metabolomic features had lower concentration in the dry eye positive group compared to the dry eye negative group. Four of these features had a Log2-fold change ≤ -1 and p value ≤.05. These warrant further study.

CONCLUSION

Although no overall global difference was observed on the principal component analysis plots, a general trend of lower metabolite concentrations in the dry eye disease group was shown. Moreover, several metabolites of interest were discovered with significantly different signal intensities between the groups. These metabolites may aid future diagnostics and serve as possible biomarkers and therapeutic targets for dry eye disease in pre-operative cataract patients.

Therapeutic Potential of Umbilical Cord MSC-Derived Exosomes in a Severe Dry Eye Rat Model: Enhancing Corneal Protection and Modulating Inflammation

Background/Objectives: Dry eye disease (DED) is a multifactorial inflammatory disease that disrupts the ocular surface, causing tear film instability, epithelial damage, and chronic inflammation. Mesenchymal stem cell-derived exosomes (MSC-exos) are promising therapeutics with immunomodulatory and regenerative properties. This study investigates the therapeutic effects of umbilical cord MSC-derived exosomes (UCMSC-exos) in a severe dry eye model, induced by a surgical resection of the infra-orbital (ILG) and extra-orbital lacrimal gland (ELG) in rats. Methods: Clinical evaluations, including tear volume measurement, slit lamp biomicroscopy, fluorescein staining, and spectral domain optical coherence tomography (SD-OCT), were performed to assess corneal neovascularization, corneal abrasion, and epithelial/stromal thickness. Histopathological analysis, immunohistochemistry, and mRNA gene expression were conducted to evaluate corneal tissue changes and inflammatory marker expression. Results: The results show that the treatment group exhibited significantly reduced corneal neovascularization compared to the control group (p = 0.030). During the first month, the Exo group also had a significantly lower corneal fluorescein staining area (p = 0.032), suggesting accelerated wound healing. SD-OCT analysis revealed that the corneal epithelial thickness in the treatment group was closer to normal levels compared to the control group (p = 0.02 and p = 0.006, respectively). UCMSC-exos treatment also modulated the expression of α-SMA and apoptosis in the cornea. Additionally, the gene expression of inflammatory cytokines (IL-1β and TNF-α) were downregulated. Conclusions: These findings suggest that MSC-exosome therapy offers a novel, cell-free regenerative approach for managing severe DED, modulating inflammatory response.

Parainflammation in the Ocular System: Considerations on the Underlying Mechanisms and Treatment of Dry Eye Disease

INTRODUCTION

The transition from regulated to dysregulated parainflammation is a new concept that needs to be elucidated to clarify the pathogenesis of dry eye disease (DED). This review summarizes the recent evidence about mechanisms that could lead to dysregulated parainflammation, proposing a new hypothesis to correlate this process with the progression to chronic inflammation.

METHODS

A group of European experts on DED participated in a roundtable to discuss the role of parainflammation in the most common ocular diseases with regard to DED. Starting from the roundtable contents, a narrative review was conducted through a PubMed search based on the main topics discussed, namely: parainflammation, dysfunctional parainflammation, tear film lipid and mucin alterations, and tear cortisol.

RESULTS

Parainflammation is involved in different ocular pathologies and is characterized by the involvement of the immune system and complement factors. In DED, continuous and persistent insults are responsible for the qualitative and quantitative alteration of the lipid and mucin components of the tear film. In addition, other contributing factors have recently been described, such as the reduction of cortisol synthesis by corneal epithelial cells. This altered condition leads to excessive macrophage activity, releasing cytokines and adhesion molecules, losing tissue homeostasis, and possibly progressing to chronic inflammation.

CONCLUSIONS

Literature evidence supports the crucial role of parainflammation and its usefulness in improving the diagnosis and treatment of DED. At the same time, further investigations are necessary to better define the transition from functional to dysfunctional parainflammation, including the role of ocular surface components other than the tear film.

A first-in-human, prospective pilot trial of umbilical cord-derived mesenchymal stem cell eye drops therapy for patients with refractory non-Sjögren's and Sjögren's syndrome dry eye disease

BACKGROUND

Patients with refractory dry eye disease (DED) often face the threat of diminished visual quality and have limited responses to existing treatments. Ocular injection of Mesenchymal stem cells (MSCs) has recently emerged as a promising new therapeutic strategy for DED. Topical eye drops are the clinical favorable choice for drug administration in DED. To date, the clinical use of MSC eye drops has not been reported in settings. This clinical trial represents a groundbreaking exploration into the preliminary therapeutic potential and safety of umbilical cord MSC eye drops for patients with refractory DED, including both non-Sjögren's dry eye (NSDE) and Sjögren's syndrome dry eye (SSDE). The study also aimed to investigate the possible underlying mechanisms.

METHODS

In this open-label, prospective, single-arm, self-controlled trial, 11 NSDE and 5 SSDE patients received twice-daily MSC eye drops for two weeks, subsequent follow-up visits were scheduled at 4 weeks and 12 months after treatment. The primary efficacy was evaluated using the ocular surface disease index (OSDI) score, tear meniscus height (TMH), non-invasive break-up time (NIBUT), Schirmer I test (SIT), and corneal fluorescein staining (CFS) score. Secondary assessments focused on the evaluation of lipid layer, meibomian gland function, and bulbar conjunctival redness. Safety was monitored by recording adverse events (AEs) throughout the study. Changes in tear levels of interleukin-6 (IL-6), IL-17A, Mucin 5AC (MUC5AC), C-C chemokine ligand 20 (CCL20) and IL-23, along with proteomic alterations, were compared between baseline and T-week2.

RESULTS

Significant clinical improvements were observed in most symptoms and signs following MSC eye drops treatment in both NSDE and SSDE patients, particularly in tear production as measured by SIT and TMH, and the alleviation of meibomian gland blockage. The therapeutic effect on OSDI, NIBUT, and the lipid layer was more pronounced in NSDE patients compared to SSDE. No serious AEs were reported during the treatment and follow-up period. Post-treatment reductions in tear levels of IL-6 and IL-17A, along with an increase in MUC5AC, further confirmed the efficacy. Tear proteomic analysis indicated that the efficacy of MSC eye drops is associated with the inhibition of inflammation caused by T helper 17 (Th17) cells in both NSDE and SSDE groups.

CONCLUSIONS

In this prospective exploratory clinical study, we have demonstrated that MSC eye drops might offer clinical efficacy and manageable safety in treating refractory DED for the first time, potentially bringing a new perspective on the treatment of such patients. Our research represents a preliminary exploratory endeavor, paving the way for future large-scale randomized positive-controlled trials.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05784519. Registered 28 February 2023, https://clinicaltrials.gov/study/NCT05784519 .

Role of Chinese Medicine Monomers in Dry Eye Disease: Breaking the Vicious Cycle of Inflammation

Dry eye disease (DED) is a chronically inflammatory ocular surface disorder of unknown pathogenesis. Anti-inflammatory medications, artificial tears, autologous serum, and LipiFlow have been shown to be highly beneficial in alleviating symptoms. Nevertheless, these interventions often provide only short-term results and do not address the underlying problems of the disease. There is growing evidence that the risk of DED is associated with a vicious cycle of inflammation. This vicious cycle of inflammation is produced by the interaction of several factors, including tear film hyperosmolarity, tear film instability, inflammation, and apoptosis. Chinese medicine monomers, distinguished by their multicomponent and multitarget advantages, have been shown to help treat DED by modulating tear film status, and inhibiting inflammatory responses, and apoptosis, providing a new way of thinking of the management of DED in Chinese medicine.

Expression of CD15 in the bulbar conjunctiva among T2DM patients with ocular surface damage

BackgroundType 2 diabetes mellitus (T2DM) is a chronic metabolic disorder, which induces ocular surface damage due to low-grade inflammation.AimTo detect and evaluate relative epithelial expression of CD15 in bulbar conjunctiva among patients with and without T2DM based on results of conjunctival impression cytology (CIC), in order to study its role in conjunctival parainflammation related to T2DM.Materials and methodsWe conducted a prospective observational study from March 2023 to December 2023. Forty-eight T2DM patients (96 eyes) were enrolled into a study group. The control group included forty (80 eyes) age- and sex-matched healthy volunteers. All patients underwent conjunctival impression cytology (CIC) and expression of CD15 in bulbar conjunctiva.ResultsExpression of CD15 was detected on epithelial cells in 95% of samples in the study group and 15% of the controls, is statistically significant (p = 0.0000). Mean expression of CD was at 0.96 ± 1.28%, and it was significantly different from the study group with the same Nelson's grade - 3.81 ± 1.48% (p = 0.0351). CD 15 values were significantly higher between Nelson II and III in the study group (3.81 ± 1.48; 7.72 ± 1.65; p = 0.0000, respectively).ConclusionsThe research shows that T2DM patients are prone to increased epithelial expression of CD 15 compared to healthy controls. Relative expression of CD15 may be utilized as a potential marker to evaluate topical treatment outcomes of ocular surface damage in T2DM.

Anti-inflammatory effects of LCB 03-0110 on human corneal epithelial and murine T helper 17 cells

Dry eye disease (DED) is a complicated disorder that impacts ocular surface and tear-film stability. Inflammation has recently been reported as the core mechanism and main therapeutic target of DED. Although anti-inflammatory drugs have been developed, they still have limited efficacy and various side effects. Recent reports have suggested that kinase inhibitors are beneficial for relieving inflammation. Therefore, this study aimed to investigate the anti-inflammatory effects of LCB 03-0110, a multi-tyrosine kinase inhibitor, on representative cell-based models (HCE- 2 and Th17 cells) of DED. While tacrolimus and tofacitinib, two different anti-inflammatory drugs that have entered clinical trials for DED treatment, did not induce any anti-inflammatory responses in HCE-2 cells, LCB 03-0110 significantly suppressed the phosphorylation of P38 and ERK and reduced the expression levels of IL-6 and IL-8 in HCE-2 cells treated with either LPS or poly(I:C). Moreover, LCB 03-0110 notably decreased the expression level of IL-17A in Th17 cells in a dose-dependent manner, whereas tofacitinib promoted IL-17A production at low concentrations but inhibited its expression at concentrations greater than 1 μM. In addition, LCB 03-0110 was found to be non-toxic to both HCE-2 and Th17 cells. In conclusion, these results suggest that LCB 03-0110 would be a promising drug candidate for the treatment of DED because of its advantages over tacrolimus and tofacitinib.

Comparison of therapeutic effects of 0.05% Cyclosporine A versus 0.1% Fluorometholone in Chinese patients with mild dry eye unresponsive to artificial tears: a randomized control study

BACKGROUND

To assess and compare the therapeutic outcomes of 0.05% Cyclosporine A (CsA) ophthalmic solution versus 0.1% Fluorometholone (FML) eyedrops in Chinese patients with mild dry eye disease (DED) unresponsive to conventional artificial tears (AT).

METHODS

A total of 43 patients with mild DED, who have failed to respond to conventional AT therapy for over 3 months, were randomly assigned to receive either 0.05% CsA or 0.1% FML twice daily for 6-months. In addition, all the patients were instructed to use 0.1% SH 4 times a day as supplementary therapy. Dry eye examination, including Ocular Surface Disease Index (OSDI) questionnaire, non-invasive tear break-up time (NIBUT), Schirmer scores, corneal fluorescein staining (CFS) scores, and conjunctival goblet cell (CGC) density, intraocular pressure (IOP), Best corrected visual acuity (BCVA) was conducted at baseline and then evaluated at 1, 3, and 6 months after treatment. Corneal endothelial cell density, corneal dendritic cells (DCs) and nerves were assessed by in vivo confocal microscopy at baseline and 6 months after treatment.

RESULTS

At 3 and 6 months after treatment, OSDI scores in the 0.05% CsA group showed more improvement than those in the 0.1% FML group. CFS was significantly lower and Schirmer scores were significantly higher in 0.05% CsA group compared with 0.1% FML group. NIBUT improved significantly in both groups, with greater improvement in the 0.05% CsA group at the 1-, 3-, and 6-month visits. Throughout the duration of the study, the 0.1% FML group exhibited no notable enhancement in CGC density. Conversely, a substantial elevation in CGC density was observed in the 0.05% CsA group. After 6 months of treatment, significantly reduced corneal DC density and area were obtained in 0.05% CsA group as compared to 0.1% FML group, while there were no significant changes in cornea nerve fiber density, cornea nerve fiber length and cornea nerve fiber width in both groups. Additionally, after 6 months of treatment, neither group showed any statistically significant changes in IOP, BCVA or in corneal endothelial cell density.

CONCLUSION

The administration of 0.05% CsA proved effective in managing mild DED, offering a supplementary advantage in improving Schirmer scores, restoring CGC density and reducing corneal DC density compared to 0.1% FML eyedrops. Consequently, 0.05% CsA eyedrops are recommended as a safe and efficacious therapeutic alternative for patients with mild DED who fail to respond to conventional tear substitutes therapy.

CLINICAL TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registry, ChiCTR2200066441, Registered 06 December 2022-Retrospectively registered.

Molecular Mechanisms Responsible for Mesenchymal Stem Cell-Dependent Attenuation of Tear Hyperosmolarity and Immune Cell-Driven Inflammation in the Eyes of Patients with Dry Eye Disease

BACKGROUND

Dry eye disease (DED) is a chronic condition characterized by a decrease in tear production or an increase in tear evaporation, leading to inflammation and damage of the ocular surface. Dysfunction of ion channels, tear hyperosmolarity and immune cell-driven inflammation create a vicious circle responsible for the pathological changes in the eyes of DED patients. Mesenchymal stem cells (MSCs) are adult, rapidly proliferating stem cells that produce a large number of immunoregulatory, angiomodulatory, and growth factors that efficiently reduce tear hyperosmolarity-induced pathological changes, inhibit harmful immune response, and provide trophic support to the injured corneal and conjuctival epithelial cells, goblet cells and acinar cells in lacrimal glands of DED patients.

METHODS

An extensive research in the literature was implemented in order to elucidate the role of MSCs in the attenuation of tear hyperosmolarity and eye inflammation in patients suffering from DED.

RESULTS

Findings obtained in preclinical and pilot clinical studies demonstrated that MSCs reduced tear hyperomsolaity-induced pathological changes and suppressed immune cell-driven eye inflammation. Additionally, MSC-based therapy managed to successfully address the most severe DED-related conditions and complications.

CONCLUSIONS

MSCs should be considered as potentially new therapeutic agents for the treatment of severe DED.

Pharmacogenomic Analysis of Response to Topical Tumor Necrosis Factor α Antagonist Licaminlimab (OCS-02) in Dry Eye Disease [RETRACTED]

PURPOSE

The purpose of this study was to evaluate the pharmacogenomics of response to topical ocular tumor necrosis factor α (TNFα) inhibitor licaminlimab in patients with DED.

METHODS

Three single-nucleotide polymorphisms (SNPs) associated with Sjögren syndrome, 3 in the TNFα gene and 1 in the TNF receptor 1 (TNFR1) gene, were assessed for association with response to licaminlimab in participants from a randomized, vehicle-controlled, Phase 2 study in which adults with DED and severe ocular discomfort persisting despite treatment with artificial tears received licaminlimab or vehicle for 6 weeks. Response was assessed for change from baseline in Global Ocular Discomfort score at Day 29 of treatment. The pharmacogenomic analysis was a prospectively specified exploratory objective of the study. mRNA expression for TNFα, interleukin (IL) 1β, and IL8 in conjunctival epithelium cells was determined. The relationship between SNPs and response to licaminlimab was assessed using a mixed model repeated measures analysis.

RESULTS

SNP rs1800693 in the TNFR1 gene showed a significant effect on response to licaminlimab ( P < 0.0001, initial association test); no effect was seen for any of the other SNPs tested. The CC genotype of rs1800693 was associated with much greater response to licaminlimab than the CT or TT genotypes: LS mean changes from baseline to Day 29 in Global Ocular Discomfort score were -29.5, -0.09, and -3.90, in patients with the CC, CT, and TT genotypes, respectively ( P < 0.0001). No significant effect was observed in vehicle-treated patients. Improvements from baseline were seen in 3/4 licaminlimab-treated participants with the CC genotype. Conjunctival epithelium cell levels of mRNA for TNFα, IL1β, and IL8 decreased from baseline in participants with the CC genotype, but not with the CT or TT genotypes. Between-genotype differences in mRNA levels were not observed in participants receiving vehicle.

CONCLUSIONS

The CC genotype of rs1800693, relatively common in patients with DED, was strongly associated with response to licaminlimab and decreased inflammatory cytokine gene expression in ocular surface cells during treatment. This study is one of the first to our knowledge to investigate pharmacogenomics in the treatment of DED.

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.

Mucoadhesive phenylboronic acid-grafted carboxymethyl cellulose hydrogels containing glutathione for treatment of corneal epithelial cells exposed to benzalkonium chloride

Benzalkonium chloride (BAK) is the most commonly-used preservative in topical ophthalmic medications that may cause ocular surface inflammation associated with oxidative stress and dry eye syndrome. Glutathione (GSH) is an antioxidant in human tears and able to decrease the proinflammatory cytokine release from cells and reactive oxygen species (ROS) formation. Carboxymethyl cellulose (CMC), a hydrophilic polymer, is one of most commonly used artificial tears and can promote the corneal epithelial cell adhesion, migration and re-epithelialization. However, most of commercial artificial tears provide only temporary relief of irritation symptoms and show the short-term treatment effects. In the study, 3-aminophenylboronic acid was grafted to CMC for increase of mucoadhesive properties that might increase the precorneal retention time and maintain the effective therapeutic concentration on the ocular surface. CMC was modified with different degree of substitution (DS) and characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Phenylboronic acid (PBA)-grafted CMC hydrogels have interconnected porous structure and shear thinning behavior. Modification of CMC with high DS (H-PBA-CMC) shows the strong bioadhesive force. The optimal concentration of GSH to treat corneal epithelial cells (CECs) was evaluated by cell viability assay. H-PBA-CMC hydrogels could sustained release GSH and decrease the ROS level. H-PBA-CMC hydrogels containing GSH shows the therapeutic effects in BAK-damaged CECs via improvement of inflammation, apoptosis and cell viability. After topical administration of developed hydrogels, there was no ocular irritation in rabbits. These results suggested that PBA-grafted CMC hydrogels containing GSH might have potential applications for treatment of dry eye disease.

Effect of low dose honey on the apoptosis and inflammation gene expression in corneal limbal stem cells and keratocytes and its efficacy as an ophthalmic formulation in the treatment of dry eye: in-vitro and clinical study

Background

The use of honey as an eye treatment encounters challenges due to its high osmolarity, low pH, and difficulties in sterilization. This study addresses these issues by employing a low concentration of honey, focusing on both in-vitro experiments and clinical trials for treating dry eye disease in corneal cells.

Methods

In the in-vitro experiment, we investigated the impact of a 1% honey-supplemented medium (HSM) on limbal stem cells (LSCs) and keratocytes using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and real-time polymerase chain reaction (PCR) for BCL-2, BAX, and IL-1β gene expression. Simultaneously, in the clinical trial, 80 participants were divided into two groups, receiving either a 1% w/v honey ophthalmic formulation or a placebo for 3 months. Study outcomes included subjective improvement in dry eye symptoms, tear break-up time (TBUT), and Schirmer's test results.

Results

MTT results indicated that 1% HSM did not compromise the survival of corneal cells and significantly reduced the expression of the IL-1β gene. Additionally, participants in the honey group demonstrated a higher rate of improvement in dry eye symptoms and a significant enhancement in TBUT values at the three-month follow-up. However, there was no significant difference between the study groups in terms of Schirmer's test values. No adverse events were observed or reported.

Conclusion

In conclusion, 1% honey exhibits anti-inflammatory and anti-infective properties, proving effective in ameliorating dry eye symptoms and enhancing tear film stability in patients with dry eye disease.Clinical Trial Registration: https://irct.behdasht.gov.ir/trial/63800.

The role of oxidative stress in the pathogenesis of ocular diseases: an overview

Dysregulation of oxidative stress serves as a pivotal predisposing or exacerbating factor in the intricate development of numerous pathological processes and diseases. In recent years, substantial evidence has illuminated the crucial role of reactive oxygen species (ROS) in many fundamental cellular functions, including proliferation, inflammation, apoptosis, and gene expression. Notably, producing free radicals within ROS profoundly impacts a wide range of biomolecules, such as proteins and DNA, instigating cellular damage and impairing vital cellular functions. Consequently, oxidative stress emerges as a closely intertwined factor across diverse disease spectra. Remarkably, the pathogenesis of several eye diseases, including age-related macular degeneration, glaucoma, and diabetic retinopathy, manifests an intrinsic association with oxidative stress. In this comprehensive review, we briefly summarize the recent progress in elucidating the intricate role of oxidative stress in the development of ophthalmic diseases, shedding light on potential therapeutic avenues and future research directions.

Morphological and functional characteristics of the meibomian gland in pediatric patients with epiblepharon

BACKGROUND

To observe morphologic and functional changes in meibomian glands in pediatric patients with and without lower eyelid epiblepharon.

METHODS

In this prospective observation study, 55 eyes of 55 patients( 24 males, 31 females; mean age ± SD,9.82 ± 2.59 years; range 6-14 years) and 60 eyes of 60 controls ( 32 males, 28 females; mean age ± SD,10.57 ± 2.75 years; range 6-14 years) were included. The following tests were performed: eyelid margin abnormality by slit-lamp examination, measurement of noninvasive keratographic break-up time (NIKBUT), grading of absence of meibomian gland (meibography score) assessed with noncontact meibography, morphologic changes of meibomian glands (thinning, dilatation and distortion), tear production by the Schirmer 1 test, and grading of meibum quality and meibomian gland expressibility.

RESULTS

The morphologic changes in meibomian glands were more common in the epiblepharon group (56.36%) than in the control group (28.33%) (p = 0.002). The meibum quality was worse in the epiblepharon group than in the control group (p = 0.009), and the NIKBUT was significantly shorter in the epiblepharon group than in the control group (p = 0.012). There was no significant difference in the Schirmer 1 test, meibomian gland expressibility, eyelid margin abnormality score or total meibography score between the two groups. Morphologic changes in the meibomian glands in the upper eyelids (38.18%) were more common than those in the lower eyelids (20%) (p = 0.036) in the epiblepharon group, and the meibography score was higher in the upper eyelids than in the lower eyelids (p = 0.001).

CONCLUSION

There are morphological and functional changes in meibomian glands in pediatric patients with lower eyelid epiblepharon. Although the inverted eyelashes were located in the lower eyelid, morphological changes in the meibomian glands were more common in the upper eyelid.

Aprepitant Restores Corneal Sensitivity and Reduces Pain in DED

Purpose

This study aims to assess the efficacy of two aprepitant formulations (X1 and X2), in a preclinical model of dry eye disease (DED) induced by benzalkonium chloride (BAK).

Methods

Two aprepitant formulations were tested on 7 to 8-week-old male mice for their efficacy. In vivo corneal fluorescein staining assessed epithelial damage as the primary end point on days 0, 3, 5, 7, 9, 12, and 14 using slit-lamp microscopy. The DED model was induced with 0.2% BAK twice daily for the first week and once daily for the next week. Mice were randomly assigned to 5 treatment groups: Aprepitant X1 (n = 10) and X2 (n = 10) formulation, 2 mg/mL dexamethasone (n = 10), control vehicle X (n = 10), 0.2% hyaluronic acid (n = 10), or no treatment (n = 10). Eye wiping, phenol red, and Cochet Bonnet tests assessed ocular pain, tear fluid secretion, and nerve function. After 7 days, the mice were euthanized to quantify leukocyte infiltration and corneal nerve density.

Results

Topical aprepitant X1 reduced BAK-induced corneal damage and pain compared to gel vehicle X (P = 0.007) and dexamethasone (P = 0.021). Aprepitant X1 and X2 improved corneal sensitivity versus gel vehicle X and dexamethasone (P < 0.001). Aprepitant X1 reduced leukocyte infiltration (P < 0.05) and enhanced corneal nerve density (P < 0.001). Tear fluid secretion remained statistically unchanged in both the X1 and X2 groups.

Conclusions

Aprepitant formulation X1 reduced pain, improved corneal sensitivity and nerve density, ameliorated epitheliopathy, and reduced leukocyte infiltration in male mouse corneas.

Translational Relevance

Aprepitant emerges as a safe, promising therapeutic prospect for the amelioration of DED's associated symptoms.

Managing Dry Eye Disease with Novel Medications: Mechanism, Study Validity, Safety, Efficacy, and Practical Application

Dry eye disease (DED) is a common condition that affects mainly older individuals and women. It is characterized by reduced tear production and increased tear evaporation. Symptoms include burning, irritation, tearing, and blurry vision. This paper reviews key trials of various new DED treatments, including their mechanism of action, study outcomes, safety, and efficacy. The paper also includes a critical assessment of the trial's validity and potential pharmacy applications of these new treatments. The literature search was conducted through PubMed, the Cochrane Central Register of Controlled Trials, and Google Scholar. The keywords "Dry Eye Disease", "lifitegrast", "cyclosporine", "loteprednol etabonate", "varenicline nasal spray", and "perfluorohexyloctane" were used to identify these medications' landmark trials. The articles deemed these medications safe and efficacious, with minimal side effects. Our randomized controlled trial validity comparison found the trials robust with predominantly low bias. Cyclosporine and loteprednol are effective when artificial tears fail, while perfluorohexyloctane reduces tear film evaporation and is preservative-free. Varenicline offers drug delivery via the nasal route and is appropriate for contact lens users. In conclusion, these FDA-approved novel medications exhibit safety and efficacy in managing DED. Further research is needed on long-term outcomes, efficacy, and side-effect comparisons, and combination therapy benefits.

Individuals with Diabetes Mellitus Have a Dry Eye Phenotype Driven by Low Symptom Burden and Anatomic Abnormalities

Dry eye disease is an umbrella term that includes a variety of symptoms and signs. A link between diabetes mellitus and dry eye disease exists, but the associated phenotype needs further examination. Thus, our aim was to determine how diabetes mellitus relates to the dry eye disease phenotype. A prospective, cross-sectional study was conducted at the Miami Veteran Affairs Medical Center ophthalmology clinic between October 2013 and September 2019. Participants included a volunteer sample of 366 South Florida veterans with one or more symptoms or signs of dry eye disease [Dry Eye Questionnaire-5 ≥ 6 OR tear break-up time ≤ 5 OR Schirmer's test score ≤ 5 OR corneal fluorescein staining ≥ 2]. Participants were divided into three groups: (1) individuals without diabetes mellitus (controls); (2) individuals with diabetes mellitus but without end-organ complications; and (3) individuals with diabetes mellitus and end-organ complications. Dry eye metrics were compared across groups. The main outcome measures included ocular symptom questionnaires [e.g., 5-item Dry Eye Questionnaire, Ocular Surface Disease Index, and ocular pain assessment] and clinical parameters obtained from an ocular surface evaluation. A total of 366 individuals were included (mean age 59 ± 6 years; 89% males; 39% White; 11% diabetes mellitus and end-organ complications; 15% diabetes mellitus but without end-organ complications). Individuals with diabetes mellitus and end-organ complications had lower symptom scores on the dry eye disease and pain-specific questionnaires compared to individuals with diabetes mellitus but without end-organ complications and controls (Ocular Surface Disease Index: 42.1 ± 24.5 vs. 38.9 ± 25.1 vs. 23.6 ± 16.2; p < 0.001; numerical rating scale of ocular pain intensity: 4.9 ± 3.2 vs. 4.3 ± 2.7 vs. 3.5 ± 2.7; p = 0.02). Eyelid laxity was also more severe in the group with diabetes mellitus and end-organ complications (0.69 ± 0.64 vs. 0.73 ± 0.72 vs. 1.08 ± 0.77; p = 0.004) compared to the two other groups. The diabetic dry eye disease phenotype is driven by signs more so than by symptoms, with anatomic eyelid abnormalities being more frequent in individuals with diabetes mellitus and end-organ complications. Given this, ocular surface abnormalities in individuals with DM may be missed if screened by symptoms alone. As such, individuals with DM should undergo a slit lamp examination for signs of ocular surface disease, including anatomic abnormalities.

The cGAS-STING pathway-dependent sensing of mitochondrial DNA mediates ocular surface inflammation

The innate immune response is the main pathophysiological process of ocular surface diseases exposed to multiple environmental stresses. The epithelium is central to the innate immune response, but whether and how innate immunity is initiated by ocular epithelial cells in response to various environmental stresses in ocular surface diseases, such as dry eye, is still unclear. By utilizing two classic experimental dry eye models-a mouse ocular surface treated with benzalkonium chloride (BAC) and a mouse model with surgically removed extraorbital lachrymal glands, as well as dry eye patient samples-along with human corneal epithelial cells (HCE) exposed to hyperosmolarity, we have discovered a novel innate immune pathway in ocular surface epithelial cells. Under stress, mitochondrial DNA (mtDNA) was released into the cytoplasm through the mitochondrial permeability transition pore (mPTP) and further activated the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, aggravating downstream inflammatory responses and ocular surface damage. Genetic deletion or pharmacological suppression of STING and inhibition of mtDNA release reduced inflammatory responses, whereas mtDNA transfection supported cytoplasmic mtDNA-induced inflammatory responses by activating the cGAS-STING pathway. Our study clarified the cGAS-STING pathway-dependent sensing of mitochondrial DNA-mediated ocular surface inflammation, which elucidated a new mechanism of ocular surface diseases in response to multiple environmental stresses.

The environment and dry eye-manifestations, mechanisms, and more

Dry eye disease (DED) is a multifactorial condition that often presents with chronic symptoms of pain (that can be characterized as "dryness," "burning," and "irritation," to name a few) and/or fluctuating or poor-quality vision. Given its multifactorial nature, several pathophysiologic mechanisms have been identified that can underlie symptoms, including tear film, ocular surface, and/or corneal somatosensory nerve abnormalities. Research has focused on understanding how environmental exposures can increase the risk for DED flares and negatively impact the tear film, the ocular surface, and/or nerve health. Given that DED is a common condition that negatively impacts physical and mental functioning, managing DED requires multiple strategies. These can include both medical approaches and modulating adverse environmental conditions, the latter of which may be a cost-effective way to avoid DED flares. Thus, an understanding of how environmental exposures relate to disease is important. This Review summarizes research on the relationships between environmental exposures and DED, in the hope that this information will engage healthcare professionals and patients to consider environmental manipulations in their management of DED.

Rabbit models of dry eye disease: comparative analysis

AIM

To report ocular changes in rabbits after the implementation of three different induction methods to create dry eye (DE) conditions and provides evidence of DE-related disease evolution.

METHODS

Experimental methods were divided into 3 models. The first model used involved triple injection of complete Freund's adjuvant, 50 µL each, also called the meibomian gland dysfunction (MGD) model. In the second model, DE conditions were created by the resection of nictitating membranes (NM), Harderian glands (HG), and main lacrimal glands (LG), also called the LGR model. The third model involved the topical administration of benzalkonium chloride (BAK) 0.1% solution. The Schirmer test, ocular surface staining with fluorescein, and tear break-up time tests were implemented before and after excision. After euthanasia, the ocular tissues were dissected. Cornea, conjunctiva, and meibomian glands were treated with periodic acid-Schiff (PAS) staining and haematoxylin-eosin staining.

RESULTS

The MGD model triggered inflammation of meibomian glands. It detected changes in the lipid layer of the tear film. The bilateral resection of NM, HG, and LG reduced the watering layer of the tear film. The topical administration of BAK of 0.1% solution impacted the mucosal layer of the tear film.

CONCLUSION

Different changes are observed with different DE syndrome models. The composition of the tear film differ depending on which part of the eye is targeted. More studies need to be done to confirm whether an increased thickness of the cornea has any impact on the DE disease.

Hyperosmolarity promotes macrophage pyroptosis by driving the glycolytic reprogramming of corneal epithelial cells in dry eye disease

Tear film hyperosmolarity plays a core role in the development of dry eye disease (DED) by mediating the disruption of ocular surface homeostasis and triggering inflammation in ocular surface epithelium. In this study, the mechanisms involving the hyperosmolar microenvironment, glycolysis mediating metabolic reprogramming, and pyroptosis were explored clinically, in vitro, and in vivo. Data from DED clinical samples indicated that the expression of glycolysis and pyroptosis-related genes, including PKM2 and GSDMD, was significantly upregulated and that the secretion of IL-1β significantly increased. In vitro, the indirect coculture of macrophages derived from THP-1 and human corneal epithelial cells (HCECs) was used to discuss the interaction among cells. The hyperosmolar environment was found to greatly induce HCECs' metabolic reprogramming, which may be the primary cause of the subsequent inflammation in macrophages upon the activation of the related gene and protein expression. 2-Deoxy-d-glucose (2-DG) could inhibit the glycolysis of HCECs and subsequently suppress the pyroptosis of macrophages. In vivo, 2-DG showed potential efficacy in relieving DED activity and could significantly reduce the overexpression of genes and proteins related to glycolysis and pyroptosis. In summary, our findings suggested that hyperosmolar-induced glycolytic reprogramming played an active role in promoting DED inflammation by mediating pyroptosis.

Role of topical and systemic immunosuppression in aqueous-deficient dry eye disease

Immunosuppression in aqueous-deficient dry eye disease (ADDE) is required not only to improve the symptoms and signs but also to prevent further progression of the disease and its sight-threatening sequelae. This immunomodulation can be achieved through topical and/or systemic medications, and the choice of one drug over the other is determined by the underlying systemic disease. These immunosuppressive agents require a minimum of 6-8 weeks to achieve their beneficial effect, and during this time, the patient is usually placed on topical corticosteroids. Antimetabolites such as methotrexate, azathioprine, and mycophenolate mofetil, along with calcineurin inhibitors, are commonly used as first-line medications. The latter have a pivotal role in immunomodulation since T cells contribute significantly to the pathogenesis of ocular surface inflammation in dry eye disease. Alkylating agents are largely limited to controlling acute exacerbations with pulse doses of cyclophosphamide. Biologic agents, such as rituximab, are particularly useful in patients with refractory disease. Each group of drugs has its own side-effect profiles and requires a stringent monitoring schedule that must be followed to prevent systemic morbidity. A customized combination of topical and systemic medications is usually required to achieve adequate control, and this review aims to help the clinician choose the most appropriate modality and monitoring regimen for a given case of ADDE.

Omega-3 fatty acids supplements for dry eye - Are they effective or ineffective?

Purpose

To evaluate effectiveness of omega-3 fatty acid supplements in relieving dry eye symptoms and signs in symptomatic visual display terminal users (VDT).

Methods

A randomized controlled study was done; eyes of 470 VDT users were randomized to receive four capsules twice daily for 6 months (O3FAgroup), each containing 180 mg of eicosapentaenoic acid and 120 mg docosahexaenoic acid. The O3FA group was compared with another group (n = 480) who received four capsules of a placebo (olive oil) twice daily. Patients were evaluated at baseline, 1, 3, and 6 months, respectively. The primary outcome was improvement in omega-3 index (a measure of EPA and DHA ratio in RBC membrane). Secondary outcomes were improvement dry eye symptoms, Nelson grade on conjunctival impression cytology, Schirmer test values, tear film breakup time (TBUT), and tear film osmolarity. Means of groups (pre-treatment, 1, 3, and 6-months) were compared with repeated measure analysis of variance.

Results

At baseline, 81% patients had low omega-3 index. In the O3FA group, a significant increase in omega-3 index, improvement in symptoms, reduction in tear film osmolarity, and increase in Schirmer, TBUT, and goblet cell density was observed. These changes were not significant in the placebo group. Improvement in test parameters was significantly (P < 0.001) better in patients with low omega3 index (<4%) subgroup.

Conclusion

Dietary omega-3 fatty acids are effective for dry eye in VDT users; omega-3 index appears to be the predictor to identify potential dry eye patients who are likely to benefit from oral omega-3 dietary intervention.

Systemic Lupus Erythematosus and Risk of Dry Eye Disease and Corneal Surface Damage: A Population-Based Cohort Study

Systemic lupus erythematosus (SLE) potentially involves multiple parts of the ocular system, including the lacrimal glands and the cornea. The present study sought to assess the risk of aqueous-deficient dry eye disease (DED) and corneal surface damage in patients with SLE. We conducted a population-based cohort study using Taiwan's National Health Insurance research database to compare the risks of DED and corneal surface damage between subjects with and without SLE. Proportional hazard regression analyses were used to calculate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) for the study outcomes. The propensity score matching procedure generated 5083 matched pairs with 78,817 person-years of follow-up for analyses. The incidence of DED was 31.90 and 7.66 per 1000 person-years in patients with and without SLE, respectively. After adjusting for covariates, SLE was significantly associated with DED (aHR: 3.30, 95% CI: 2.88-3.78, p < 0.0001) and secondary Sjögren's syndrome (aHR: 9.03, 95% CI: 6.86-11.88, p < 0.0001). Subgroup analyses demonstrated that the increased risk of DED was augmented among patients with age < 65 years and female sex. In addition, patients with SLE had a higher risk of corneal surface damage (aHR: 1.81, 95% CI: 1.35-2.41, p < 0.0001) compared to control subjects, including recurrent corneal erosion (aHR: 2.98, 95% CI: 1.63-5.46, p = 0.0004) and corneal scar (aHR: 2.23, 95% CI: 1.08-4.61, p = 0.0302). In this 12-year nationwide cohort study, we found that SLE was associated with increased risks of DED and corneal surface damage. Regular ophthalmology surveillance should be considered to prevent sight-threatening sequelae among patients with SLE.

Lysine Demethylase 1B Promotes Tear Secretion Disorder in Sjogren's Syndrome by Regulating the PAX6/CLU Axis

The impacts of lysine demethylase 1B (KDM1B) have been probed in multiple diseases, but the effects of KDM1B on SS remained obscure. The study aimed to unravel the efficiency of KDM1B on SS progression via the paired box 6 (PAX6)/clusterin (CLU) axis. NOD^{B10. H2b} mice were selected to establish the SS model. KDM1B, Pax6, and CLU expression in SS mice was assessed. Adeno-associated viruses carrying KDM1B, Pax6, and CLU were injected into the SS mice to detect tear secretion, epithelium corneal fluorescein staining scores, and levels of specific markers of lacrimal gland epithelial cells, neurotransmitter receptors that induce secretion from the lacrimal gland, and genes encoding normal tear components. The relation among KDM1B, Pax6, and CLU was examined. The rescue experiments were conducted for verifying the interaction among KDM1B, Pax6, and CLU. KDM1B expression was elevated, while Pax6 and CLU levels were decreased in the lacrimal gland tissues of SS mouse models. KDM1B decrement and Pax6 augmentation improved tear secretion, reduced corneal fluorescein staining score, decreased levels of specific markers of lacrimal gland epithelial cells, and increased levels of neurotransmitter receptors that induce secretion from the lacrimal gland and genes encoding normal tear components. KDM1D suppressed Pax6 expression by mediating H3K4me2 demethylation. Pax6 promoted the expression of CLU at the transcriptional level by binding to the CLU promoter. Silencing of Pax6 or CLU could reverse the effects of KDM1B reduction on improving the tear secretion disorder of SS mice. Silencing KDM1B mitigates the tear secretion disorder of SS mice via modulating the Pax6/CLU axis.

Using Network Pharmacology and Molecular Docking to Explore the Mechanism of Qiju Dihuang Pill against Dry Eye Disease

Background

Dry eye disease (DED) is a multifactorial disease of the ocular surface, which affects the quality of life and work efficiency of affected patients. The traditional Chinese medicine formula Qiju Dihuang Pill (QJDHP) has a good therapeutic effect on DED. However, the pharmacological mechanism is not clear.

Objective

To explore the mechanism of QJDHP in the treatment of DED based on network pharmacology.

Method

The active components in QJDHP were screened in Traditional Chinese Medicine Systems Pharmacology (TCMSP), and putative molecular targets of QJDHP were identified using the SwissTargetPrediction database. DED-related targets were screened by GeneCards and OMIM. We established protein-protein interaction (PPI) and core targets and corresponding active compound network by Cytoscape to identify the core targets and main compounds of QJDHP against DED. DAVID database was utilized for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Molecular docking was used to evaluate the binding activity between key active compounds and core targets.

Results

The results of network pharmacology showed that 253 targets of QJDHP were related to DED. PPI network analysis showed the 18 core targets. The binding affinity of docking results ranged from -5.7 to -9.3 kcal/mol, indicating a good docking effect. The results of GO enrichment analysis showed that the mechanism of QJDHP in the treatment of DED mainly involved biological processes such as apoptosis, oxidative stress, response to estrogen, angiogenesis, and the regulation of transcription factors. KEGG analysis showed that QJDHP may be regulated by the TNF signaling pathway, Toll-like receptor signaling pathway, MAPK signaling pathway, and estrogen signaling pathway in the treatment of DED.

Conclusion

In this study, we demonstrated the multicomponent, multitarget, and multichannel action mechanism of QJDHP in the treatment of DED and provided a foundation for further drug development research.

Mesenchymal Stromal Cells-Derived Extracellular Vesicles Regulate Dendritic Cell Functions in Dry Eye Disease

We explored the therapeutic efficacy of Mesenchymal stromal cells-derived extracellular vesicles (MSC-EVs) and its inhibition of the functions of dendritic cells (DCs) in dry eye disease (DED). MSC-EVs were isolated from the culture supernatants of mesenchymal stromal cells (MSCs) and characterized. In vitro, human corneal epithelial cells (HCECs) were cultured in hyperosmotic medium to simulate the DED hyperosmotic environment and treated with MSC-EVs. Cell viability was assessed, and the expression of inflammatory cytokines was quantified. Next, we induced DED in female C57BL/6 mice and divided the mice into groups treated with either MSC-EVs or phosphate buffer solution (PBS) eye drops. Disease severity was assessed; mRNA expression of inflammatory cytokines was analyzed by RT-PCR; and Th17 cells were detected by flow cytometry. Lastly, we evaluated DCs by immunofluorescence and flow cytometric analysis to assess its amounts and maturation. MSC-EVs showed protective effects on HCECs under hyperosmotic stress in vitro, suppressing the expression of inflammatory cytokines. In vivo, mice topically treated with MSC-Evs presented reduced DED disease severity compared to PBS-treated mice. MSC-Evs downregulated the expression of inflammatory cytokines, including TNF-α, IL-6, and IL-1β, as well as the frequency of Th17 cells. Further investigation showed that MSC-EVs suppressed the increase of amounts and the maturation of DCs in DED. Changes of morphological characters of DCs were also inhibited by MSC-EVs. Our study revealed that MSC-EVs suppressed ocular surface inflammation by inhibiting DCs activation-mediated Th17 immune responses, explicating the therapeutic potential of MSC-EVs in DED and other ocular surface diseases.

Hyaluronic acid in the treatment of dry eye disease

Dry eye disease (DED) is a highly prevalent and debilitating condition affecting several hundred million people worldwide. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan commonly used in the treatment of DED. This review aims to critically evaluate the literature on the safety and efficacy of artificial tears containing HA used in DED treatment. Literature searches were conducted in PubMed, including MEDLINE, and in Embase via Ovid with the search term: "(hyaluronic acid OR hyaluronan OR hyaluronate) AND (dry eye OR sicca)". A total of 53 clinical trials are included in this review, including eight placebo-controlled trials. Hyaluronic acid concentrations ranged from 0.1% to 0.4%. Studies lasted up to 3 months. A broad spectrum of DED types and severities was represented in the reviewed literature. No major complications or adverse events were reported. Artificial tears containing 0.1% to 0.4% HA were effective at improving both signs and symptoms of DED. Two major gaps in the literature have been identified: 1. no study investigated the ideal drop frequency for HA-containing eyedrops, and 2. insufficient evidence was presented to recommend any specific HA formulation over another. Future investigations assessing the optimal drop frequency for different concentrations and molecular weights of HA, different drop formulations, including tonicity, and accounting for DED severity and aetiology are essential for an evidence-based, individualized approach to DED treatment.

Hyaluronic acid in the treatment of dry eye disease

Dry eye disease (DED) is a highly prevalent and debilitating condition affecting several hundred million people worldwide. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan commonly used in the treatment of DED. This review aims to critically evaluate the literature on the safety and efficacy of artificial tears containing HA used in DED treatment. Literature searches were conducted in PubMed, including MEDLINE, and in Embase via Ovid with the search term: "(hyaluronic acid OR hyaluronan OR hyaluronate) AND (dry eye OR sicca)". A total of 53 clinical trials are included in this review, including eight placebo-controlled trials. Hyaluronic acid concentrations ranged from 0.1% to 0.4%. Studies lasted up to 3 months. A broad spectrum of DED types and severities was represented in the reviewed literature. No major complications or adverse events were reported. Artificial tears containing 0.1% to 0.4% HA were effective at improving both signs and symptoms of DED. Two major gaps in the literature have been identified: 1. no study investigated the ideal drop frequency for HA-containing eyedrops, and 2. insufficient evidence was presented to recommend any specific HA formulation over another. Future investigations assessing the optimal drop frequency for different concentrations and molecular weights of HA, different drop formulations, including tonicity, and accounting for DED severity and aetiology are essential for an evidence-based, individualized approach to DED treatment.

Conjunctiva Resident γδ T Cells Expressed High Level of IL-17A and Promoted the Severity of Dry Eye

Purpose

Conjunctival inflammation promotes ocular surface disorders in dry eye disease (DED). Here we identified γδ T cells as the predominant source of IL-17A in the murine conjunctiva and assessed their contribution to the pathogenesis of DED.

Methods

We enrolled 22 patients with DED, and analyzed the proportion of γδ T cells in the conjunctival epithelial samples by flow cytometry. Adult C57Bl/6 wild-type and TCRδ^−/− mice were used to induce DED models to investigate the role of γδ T cells. The characteristics of immune cell infiltration and the expression of immune-related cytokines or markers in mouse conjunctiva were analyzed by flow cytometry, Western blot, and quantitative polymerase chain reaction.

Results

The proportion of γδ T cells in the human DED conjunctiva is significantly higher in patients with severe corneal epithelial defects than in mild ones, which is consistently observed in the murine DED model. Further, a high level of IL-17A but not IFN-γ is detected in the conjunctiva of mice. The increased murine IL-17A–producing cells on the conjunctiva are identified as γδ T cells predominantly and Th17 cells to a lesser extent. Ablation of γδ T cells by antibody depletion or genetic deletion of TCRδ alleviates ocular surface damage in the murine DED model.

Conclusions

Our studies evaluate human and experimental murine DED for evidence of γδ T-cell–mediated inflammation and highlight a potential therapeutic synergy by targeting IL-17 and γδ T cells in DED treatment.

Oxytocin and secretin receptors - implications for dry eye syndrome and ocular pain

Dry eye syndrome, a form of ocular surface inflammation, and chronic ocular pain are common conditions impacting activities of daily living and quality of life. Oxytocin and secretin are peptide hormones that have been shown to synergistically reduce inflammation in various tissues and attenuate the pain response at both the neuron and brain level. The oxytocin receptor (OXTR) and secretin receptor (SCTR) have been found in a wide variety of tissues and organs, including the eye. We reviewed the current literature of in vitro experiments, animal models, and human studies that examine the anti-inflammatory and anti-nociceptive roles of oxytocin and secretin. This review provides an overview of the evidence supporting oxytocin and secretin as the basis for novel treatments of dry eye and ocular pain syndromes.

Current Advances in Mechanisms and Treatment of Dry Eye Disease: Toward Anti-inflammatory and Immunomodulatory Therapy and Traditional Chinese Medicine

Dry eye is currently one of the most common ocular surface disease. It can lead to ocular discomfort and even cause visual impairment, which greatly affects the work and quality of life of patients. With the increasing incidence of dry eye disease (DED) in recent years, the disease is receiving more and more attention, and has become one of the hot research fields in ophthalmology research. Recently, with the in-depth research on the etiology, pathogenesis and treatment of DED, it has been shown that defects in immune regulation is one of the main pathological mechanisms of DED. Since the non-specific and specific immune response of the ocular surface are jointly regulated, a variety of immune cells and inflammatory factors are involved in the development of DED. The conventional treatment of DED is the application of artificial tears for lubricating the ocular surface. However, for moderate-to-severe DED, treatment with anti-inflammatory drugs is necessary. In this review, the immunomodulatory mechanisms of DED and the latest research progress of its related treatments including Chinese medicine will be discussed.