The core mechanism of dry eye disease is inflammation

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.

Alleviative effect of probiotics and prebiotics on dry eye in type 2 diabetic mice through the gut-eye axis

Diabetes Mellitus (DM) is a metabolic disease that manifests as a state of "chronic low-grade inflammation". Patients with DM have a disorder of intestinal flora. There is a discernible correlation between this disorder of intestinal flora and the onset and progression of eye diseases, which offers novel insights into treating eye diseases through the modulation of intestinal flora. Here, we demonstrated that a high-fat diet and streptozotocin injection-induced intestinal microbiota dysbiosis can lead to dry eye-like manifestations in T2DM mice. Probiotic and prebiotic treatments not only alleviated intestinal inflammation and barrier disruption, but also mitigated damage to the lacrimal barrier and suppressed immune cell infiltration and inflammatory responses. Additional mechanism investigation found that probiotics and prebiotics inhibited the TLR4/NF-κB signaling pathway and its downstream pro-inflammatory products both in the lacrimal gland and colon. 16S RNA sequencing identified a reduction in the bacterial genera Akkermansia and Lactobacillus in the fecal samples of DM mice. By contrast, treatment with probiotics and prebiotics led to a reshaping of the intestinal microbial community and a reduction in bile acid metabolites, such as taurocholic acid and deoxycholic acid. Our current study demonstrates that probiotic and prebiotic treatments can ameliorate dry eye-like symptoms and associated pathological changes in T2DM mice. Moreover, we proved that a high-fat diet and STZ-induced microbiota dysbiosis were involved in diabetic dry eye through the gut-eye axis.

Biogenic Amino Acid Cross-Linked Hyaluronic Acid Nanoparticles Containing Dexamethasone for the Treatment of Dry Eye Syndrome

Ocular barriers, poor retention time, and frequent ocular discharge suppress the activity of Dexamethasone. Arginine (Arg) and hyaluronic acid (HA) are crucial for maintaining ocular health because of their unique biological benefits. In this study, we investigated the cationic properties of arginine to develop dexamethasone-loaded HA nanoparticles (ADHA NPs) and evaluated their therapeutic potential in alleviating dry eye syndrome using various reported in-vitro and in-vivo techniques. The ionic cross-linking method was used to prepare ADHA NPs. The ADHA NPs exhibited nearly 94.99 ± 4.16% drug release at the end of 6 h and followed the Korsemeyar-Peppas kinetic model (R2 = 0.9811). Moreover, the developed formulation exhibited a higher water retention capacity, i.e., 86.89 ± 1.41%, and revealed enhanced mucoadhesion characteristics. ADHA NPs also exhibited significant anti-inflammatory effects (p < 0.001) compared to dexamethasone in LPS-induced RAW 264.7 cell lines against proinflammatory cytokines IL-1 β, NO and TNF-α. Furthermore, cell line studies in HCECs (human corneal epithelial cells) showed cytocompatibility and a dose-dependent uptake of ADHA NPs. ADHA NPs also maintained the cell integrity against 0.005% benzalkonium chloride (BAC) induced dry eye model on HCECs. Further, the Schirmer tear test showed twofold enhanced tear production in the developed formulation, and ADHA NPs seem to maintain the uniform structure of the tear. In vivo, drug retention studies ensured the good retention properties of ADHA NPs up to 12 h. In conclusion, ADHA NPs, because of their anti-inflammatory, mucoadhesiveness, modified drug release capacity, and higher drug retention properties, could serve as a potential therapeutic alternative for treating dry eye conditions.

Bringing ophthalmology into the scientific world: Novel nanoparticle-based strategies for ocular drug delivery

The distinctive benefits and drawbacks of various drug delivery strategies to supply corneal tissue improvement for sense organs have been the attention of studies worldwide in recent decades. Static and dynamic barriers of ocular tissue prevent foreign chemicals from entering and inhibit the active absorption of therapeutic medicines. The distribution of different medications to ocular tissue is one of the most appealing and demanding tasks for investigators in pharmacology, biomaterials, and ophthalmology, and it is critical for cornea wound healing due to the controlled release rate and increased drug bioavailability. It should be mentioned that the transport of various types of medications into the different sections of the eye, particularly the cornea, is exceedingly challenging because of its distinctive structure and various barriers throughout the eye. Nanoparticles are being studied to improve medicine delivery strategies for ocular disease. Repetitive corneal drug delivery using biodegradable nanocarriers allows a medicine to remain in different parts of the cornea for extended periods of time and thus improve administration route effectiveness. In this review, we discussed eye anatomy, ocular delivery barriers, as well as the emphasis on the biodegradable nanomaterials ranging from organic nanostructures, such as nanomicelles, polymers, liposomes, niosomes, nanowafers, nanoemulsions, nanosuspensions, nanocrystals, cubosomes, olaminosomes, hybridized NPs, dendrimers, bilosomes, solid lipid NPs, nanostructured lipid carriers, and nanofiber to organic nanomaterials like silver, gold, and mesoporous silica nanoparticles. In addition, we describe the nanotechnology-based ophthalmic medications that are presently on the market or in clinical studies. Finally, drawing on current trends and therapeutic approaches, we discuss the challenges that innovative optical drug delivery systems confront and propose future research routes. We hope that this review will serve as a source of motivation and inspiration for developing innovative ophthalmic formulations.

Evaluation of in vitro pharmacological activities of medicinal mushrooms in the context of dry eye disease

Introduction

Ethnic groups worldwide use mushrooms, particularly polypores (a group of fungi with woody fruiting bodies), to manage inflammatory conditions. In this study, the in vitro anti-inflammatory potential and mycochemical composition of six polypore extracts derived from the fruit bodies of Fomes fomentarius (L.) Fr. (FF), Ganoderma lucidum (Fr.) P. Karst. (GL), Ganoderma tsugae Murrill (GT), Gloeophyllum odoratum (Wulfen) Imazeki (GO), Laricifomes officinalis (Vill.) Kotl. and Pouzar (LO), and the sclerotium of Inonotus obliquus (Fr.) Pilát (IO) were analyzed for their relevance to treat dry eye disease (DED).

Methods

Ethanolic extracts of the fungal materials were prepared and chemically characterized by UHPLC-ELSD/MS and TLC analyses before investigating the extracts' cytotoxic, antioxidant, anti-inflammatory, and lipid-stimulating properties. Radical scavenging and intracellular reactive oxygen species (ROS) assays were carried out in UVB-exposed human corneal epithelial (HCE-T) and immortalized human meibomian gland epithelial (IHMGEC) cells to evaluate antioxidant capacities. To examine the influence of the extracts of the inflammatory processes, associated with DED, a secretion assay for pro-inflammatory cytokines was conducted in UVB-exposed HCE-T and LPS-stimulated monocytic THP-1 cells. The lipid droplets secreted by IHMGECs were analyzed to determine the extracts' lipid-stimulating properties.

Results

Extracts of GT, GL, GO, and IO found to have high radical scavenging abilities. They significantly reduced intracellular ROS in UVB-exposed HCE-T and iHMGEC cells. GO and GL extracts inhibited cytokine secretion in HCE-T cells even at low concentrations. All tested extracts significantly inhibited the secretion of pro-inflammatory cytokines (IP10, IL-6, IL-8, and α) in LPS-stimulated monocytic THP-1 cells.

Conclusion

Several extracts of the investigated fungal materials exhibit multifaceted pharmacological in vitro activities. Due to low cytotoxic activity on HCE-T, iHMGEC, and THP-1 cells, extracts from GL and GO are particularly pertinent to the treatment of DED, even at low concentrations.

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.

Cytokines in age-related eye diseases: pathogenesis and potential targets for innovative therapies

Age-related eye diseases (AREDs), such as dry eye disease (DED), age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy (DR), are significant worldwide health concerns due to their rising prevalence and debilitating effects. Despite substantial research on the pathobiology of AREDs, the impact of immune-related alterations caused by aging is still not well understood. Tissue-resident cells and invading immune cells in the eye control innate responses in the event of damage or infection. However, as cells age, they gradually lose their ability to perform their protective duties and develop abnormal characteristics. Therefore, the disrupted regulation of immune responses in the eyes of older individuals enhances their vulnerability to and the intensity of eye disorders. Cytokines, immune system components, have a role in developing AREDs by contributing to inflammation. This paper examines the deficiencies in the pathogenic and therapeutic aspects of pro-inflammatory cytokines in AREDs that require further investigation in future studies.

Treatment of Meibomian Gland Dysfunction by Classical Eyelid Hygiene Measures With and Without Additional Lipid Substitution for Tear Film Stabilization

OBJECTIVE

This study aimed to document the treatment success of eyelid hygiene with liposomal suspension using new diagnostic tools and to determine whether additional lipid substitution provided measurable benefits in meibomian gland dysfunction.

METHODS

A single-center controlled, partially single masked study was conducted. Group A used eyelid hygiene only, whereas group B additionally applied a liposomal eye spray. Subjective perception using the Ocular Surface Disease Index (OSDI) questionnaire, measurement of tear film osmolarity, noninvasive tear film break-up time, assessment of the lipid layer, meibography, inspection of lid margins, assessment of the meibomian glands, and measurement of matrix-metallopeptidase-9 were collected at baseline and after 12 weeks.

RESULTS

Eighty-two patients were included and randomized into two groups. Both groups showed a decrease in OSDI score ( P <0.001), an increase in lipid layer thickness ( P <0.001), significant improvement in the degree of loss of meibomian glands ( P <0.001), in the damage pattern of the eyelid margins ( P <0.001), in the quality of meibomian gland secretion, and in matrix-metallopeptidase-9 after 12 weeks.

CONCLUSIONS

Our study confirms the success of treatment with eyelid hygiene measures using a liposomal suspension. The additional benefit of lipid substitution was not significant after 12 weeks of treatment.

Mass spectrometry (MS)-based metabolomics of plasma and urine in dry eye disease (DED)-induced rat model

Dry eye disease (DED) is an ophthalmic disease associated with poor quality and quantity of tears, and the number of patients is steadily increasing. The aim of this study was to determine plasma and urine metabolites obtained from DED scopolamine animal model where dry eye conditions (DRY) are induced. It was also of interest to examine whether DED (scopolamine) rat model was exacerbated by treatment with benzalkonium chloride (BAC). Subsequently, plasma and urine metabolites were analyzed using liquid chromatography (LC) and gas chromatography (GC)-mass spectrometry (MS), respectively. Data demonstrated that DED indicators such as tear volume, tear breakup time (TBUT), and corneal damage in the DED groups (DRY and BAC group) differed from those of control (CON). Similar results were noted in inflammatory factors such as interleukin (IL-1β), IL-6, and tumor necrosis factor (TNF)-α. In the partial least squares-discriminant analysis (PLS-DA) score plots, the three groups were distinctly separated from each other. In addition, the related metabolites were also associated with these distinct separations as evidenced by 9 and 14 in plasma and urine, respectively. Almost all of the selected metabolites were decreased in the DRY group compared to CON, and the BAC group was lower than the DRY. In plasma and urine, lysophosphatidylcholine/lysophosphatidylethanolamine, organic acids, amino acids, and sugars varied between three groups, and these metabolites were related to inflammation and oxidative stress. Data suggest that treatment with scopolamine with/without BAC-induced DED and affected the level of systemic metabolites involved in inflammation and oxidative stress.

Longitudinal Analysis of Tear Cytokine Ratios in Association with Dry Eye Signs and Symptoms in the Dry Eye Assessment and Management (DREAM) Study

PURPOSE

To extend cross-sectional data on cytokine ratios (CRs) in dry eye disease (DED) signs by investigating longitudinal change in pro- to anti-inflammatory CRs and associations with change in DED signs and symptoms.

METHODS

Secondary analysis of fifty-four subjects [mean age 57.3 (SD 13.2) years, 85.2% female; 68.5% white] with ≥ 4 uL pooled tear volumes at months 0, 6, and 12. Pro-inflammatory (IL-1b, IL-6, IL-8, IL-17A, IFN-g, and TNF-a) to anti-inflammatory (IL-6, IL-10) cytokine ratios (CR) were calculated. DED signs (corneal and conjunctival staining scores, tear break-up time, Schirmer test, Meibomian gland plugging, tear osmolarity, composite sign severity score) and symptoms [Ocular Surface Disease Index (OSDI)] were measured. Changes over time in DED signs, symptoms, and CRs were evaluated using longitudinal models. Correlations between changes in CR and changes in DED signs and symptoms were evaluated using Spearman correlation coefficients (rho).

RESULTS

DED signs which improved over time (p < 0.001) included corneal and conjunctival staining score, tear break-up time, tear osmolarity, and composite sign severity score. Using IL-10 as anti-inflammatory, changes in corneal and conjunctival staining and composite severity score significantly correlated with changes in pro- to anti-inflammatory CRs from month 0 to 6 (|rho|: 0.29-0.45, p: 0.003-0.04) but not between month 0 to 12 (|rho|: 0.01 to 0.24, all p > 0.08). DED symptoms decreased across one year (p < = 0.001) for all OSDI measures; these changes did not correlate with changes in CRs (|rho|: 0.00 to 0.29, all p > 0.04).

CONCLUSIONS

Improvement in some DED signs across one year correlated weakly with decreases in pro- to anti-inflammatory CRs, in alignment with the understanding of DED as inflammatory. CRs may provide greater insight than absolute tear cytokine concentrations as possible DED biomarkers. Additional studies that provide standardized clinical information and tear collection and analysis are needed to validate CRs in DED.

miR-214-3p inhibits LPS-induced macrophage inflammation and attenuates the progression of dry eye syndrome by regulating ferroptosis in cells

BACKGROUND

Dry eye disease (DED) is an ocular illness caused by insufficient tear secretion or poor tear quality, and inflammation is a key factor in its pathogenesis. Previous studies have shown that miRNAs are important regulatory factors in DED.

OBJECTIVE

The purpose of this study was to explore the potential mechanism by which miR-214-3p influenced the DED process by regulating the macrophage inflammatory response.

METHODS

We induced THP-1 cells to differentiate into M0 macrophages with 100 ng/mL phorbol-12-myristate-13-acetate (PMA) and then added 15 ng/mL lipopolysaccharide (LPS) to induce inflammation. The expression of related genes and proteins was detected via RT‒qPCR, Western blotting, ELISA and immunofluorescence staining; cell viability was measured using the CCK-8 assay; and flow cytometry was used to detect ROS levels.

RESULTS

In tear and serum samples from DED patients, the levels of miR-214-3p, IL-10, and Arg1 were decreased, and the levels of IL-6, TNF-α, IL-1β, and iNOS expression were increased. Moreover, the overexpression of miR-214-3p attenuated the effect of LPS and inhibited M1 polarization and inflammation in macrophages. Mechanistically, miR-214-3p inhibited macrophage ferroptosis by downregulating TFRC expression, thereby inhibiting macrophage M1 polarization and inflammation and alleviating the progression of DED.

CONCLUSIONS

Our study indicated that the upregulation of miR-214-3p expression might be a new target for DED therapy.

Identification of glutamine as a potential therapeutic target in dry eye disease

Dry eye disease (DED) is a prevalent inflammatory condition significantly impacting quality of life, yet lacks effective pharmacological therapies. Herein, we proposed a novel approach to modulate the inflammation through metabolic remodeling, thus promoting dry eye recovery. Our study demonstrated that co-treatment with mesenchymal stem cells (MSCs) and thymosin beta-4 (Tβ4) yielded the best therapeutic outcome against dry eye, surpassing monotherapy outcomes. In situ metabolomics through matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) revealed increased glutamine levels in cornea following MSC + Tβ4 combined therapy. Inhibition of glutamine reversed the anti-inflammatory, anti-apoptotic, and homeostasis-preserving effects observed with combined therapy, highlighting the critical role of glutamine in dry eye therapy. Clinical cases and rodent model showed elevated expression of glutaminase (GLS1), an upstream enzyme in glutamine metabolism, following dry eye injury. Mechanistic studies indicated that overexpression and inhibition of GLS1 counteracted and enhanced, respectively, the anti-inflammatory effects of combined therapy, underscoring GLS1's pivotal role in regulating glutamine metabolism. Furthermore, single-cell sequencing revealed a distinct subset of pro-inflammatory and pro-fibrotic corneal epithelial cells in the dry eye model, while glutamine treatment downregulated those subclusters, thereby reducing their inflammatory cytokine secretion. In summary, glutamine effectively ameliorated inflammation and the occurrence of apoptosis by downregulating the pro-inflammatory and pro-fibrotic corneal epithelial cells subclusters and the related IκBα/NF-κB signaling. The present study suggests that glutamine metabolism plays a critical, previously unrecognized role in DED and proposes an attractive strategy to enhance glutamine metabolism by inhibiting the enzyme GLS1 and thus alleviating inflammation-driven DED progression.

Therapeutic benefits of glycerol in dry eye disease

Dry eye disease (DED) is one of the most commonly diagnosed eye disorders, with a prevalence ranging from 5 to 50%, depending on the geographic location. DED is a multifactorial disorder of the tears and ocular surface, which results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. It is also accompanied by increased osmolarity of the tear film and inflammation of the surface of the eye. Multiple therapeutic agents have been used to treat DED, with glycerol emerging as a promising component of ophthalmic preparations, due to its humectant, lubricant, demulcent, and osmoprotective properties. This review aims to evaluate the current evidence concerning the therapeutic benefits of glycerol in managing DED, focusing on its possible mechanisms of action, clinical efficacy, and potential advantages over other treatments.

Caspase 3/GSDME-Mediated Corneal Epithelial Pyroptosis Promotes Dry Eye Disease

Purpose

Dry eye disease (DED) is a common ocular surface inflammatory disease with a complex pathogenesis. Herein, the role and effect of gasdermin E (GSDME) in DED pathogenesis were explored.

Methods

In vitro, flow cytometry, Cell Counting Kit-8 (CCK-8) and lactate dehydrogenase (LDH) release assays were used to determine the effects of hyperosmotic stress on pyroptosis, apoptosis, and cell viability in human corneal epithelial cells (HCECs). Quantitative PCR (qPCR) and Western blot assays were used to detect GSDME expression in HCECs and in those transfected with si-GSDMD. In vivo, GSDMD-knockout (KO) mice were used to study the role of GSDME in DED pathogenesis. The qPCR, Western blotting, and immunofluorescence were used to explore the effects of GSDME on HCEC apoptosis, pyroptosis, and the expression of related genes and proteins in GSDMD-KO mice with scopolamine-induced dry eye.

Results

Pyroptosis and cell membrane rupture occurred, and caspase-3 and GSDME protein expression increased after HCECs were treated with 312 to 500 mOsm sodium chloride. GSDME gene and protein expression levels were increased in HCECs from both si-GSDMD- and GSDMD-KO mice. Although caspase-3 expression was increased in the dry eye group of GSDMD-KO mice, HCEC apoptosis and the apoptosis-related factors PARP were not detected. The gene and protein expression levels of the pyroptosis-related factors ASC and IL-1β were greater than those in GSDMD-KO mice without dry eye.

Conclusions

GSDME is involved in DED pathogenesis by mediating inflammation via the pyroptosis pathway, GSDME inhibition may be a therapeutic target for DED.

Investigating a novel therapeutic composition for dry eye syndrome management: In vitro and in vivo studies

Dry eye syndrome (DES) presents a significant challenge in ophthalmic care, necessitating innovative approaches for effective management. This research article introduces a multifaceted strategy to address DES through the development of ocular inserts utilizing advanced technologies such as hot-melt extrusion (HME) and the CaliCut post-extrusion system. The formulation includes key ingredients targeting different layers of the tear film and associated inflammation, including hydroxypropyl cellulose (HPC), polyethylene glycol (PEG), castor oil, and dexamethasone. The study incorporates a Design of Experiments (DoE) approach, integrating HME and the precise stretching and cutting technique of CaliCut for manufacturing consistency and dimensional control of the inserts. The developed insert(s) have been systematically characterized for their physicochemical properties, release profile, and in vivo efficacy. In silico molecular docking studies have also been conducted to assess the binding affinities of formulation components with ocular mucin, elucidating their binding affinities. Preliminary results demonstrate promising potential for the developed insert in managing DES, offering preservative-free treatment, sustained drug delivery, and improved patient compliance. This study highlights the integration of advanced technologies and formulation strategies in ocular drug delivery for effective DES management.

Pharmacological in vitro profiling of Buddleja officinalis flower extracts in the context of dry eye disease

BACKGROUND

Dry eye disease (DED) is caused by inflammation on the ocular surface and insufficient quality or production of the tear film. Due to various harmful environmental conditions, a gradual increase of DED cases has been reported.

HYPOTHESIS/PURPOSE

This study aims for a comprehensive in vitro pharmacological and phytochemical profiling of two different Buddleja officinalis Maxim. extracts to assess their potential for the treatment of DED.

METHODS

A hydroethanolic (BO-HE) and a lead-like enhanced (BO-LLE) B. officinalis extract were phytochemically characterized by UHPLC-UV-MS and UHPLC-ELSD analyses. Afterwards, the effects of either BO-HE or BO-LLE on in vitro dry eye models, including human corneal epithelial cell-transformed (HCE-T) cells, immortalized human meibomian gland epithelial cells (IHMGECs) and human leukemia monocytic (THP-1) cells, and Jurkat cells, were investigated.

RESULTS

Both extracts exhibited strong anti-inflammatory properties with free radical scavenging activities and reduction of intracellular reactive oxygen species (ROS) in UVB-exposed HCE-T cells. Treatment with BO-HE or BO-LLE showed wound healing capacities. Moreover, both extracts differentially modulate mediator secretion in UVB-exposed HCE-T cells. In IHMGECs, the size of secreted lipid droplets was larger in BO-LLE treated cells. As for immune cells, a significant reduction in levels of TNF-α and IL-6 secretion by lipopolysaccharide (LPS)-exposed THP-1 cells was observed. Additionally, BO-LLE effectively inhibited intracellular calcium influx in Jurkat cells even at low concentrations.

CONCLUSION

The results of this study demonstrate pharmacological potential of B. officinalis flowers for the treatment of DED pathology with BO-LLE exerting a slightly more beneficial profile than BO-HE.

Global research hotspots and trends in anti-inflammatory studies in dry eye: a bibliometric analysis (2004-2024)

Background

Inflammation plays a crucial role in the pathophysiology of dry eye (DE). This study aims to provide a comprehensive overview of the current status, hotspots and trends in DE anti-inflammatory research through bibliometric analysis.

Method

All publications were searched using the Web of Science Core Collection (WoSCC) database from 2004 to 2024. Bibliometric analyses were performed using VOSviewer, R-bibliometrix, and CiteSpace, and data were managed using Microsoft Office Excel 2019.

Results

There were 603 papers published between 2004 and 2024 included in this study, with the number of papers increasing each year. The United States was the major contributor, with the largest number of publications and the greatest impact. Baylor College of Medicine was the most influential research institution. Pflugfelder, Stephen C. and Tsubota, Kazuo were the most prolific authors in this area of research, while Dana, Reza was the most cited author in the field with the highest impact. The Journal with the highest number of publications was Investigative Ophthalmology & Visual Science, while the highest impact journal was Ocular Surface. Research hotspots were focused on the mechanisms of inflammation in DE and interventions for anti-inflammatory therapy. Future studies would favor more inflammation-related targeted therapies and physical therapies.

Conclusion

This study is the first bibliometric analysis to comprehensively summarize research trends and developments in DE anti-inflammatory treatments, pointing out recent research frontiers and hot directions for scholars studying DE anti-inflammatory treatments.

Substance P regulates memory Th17 cell generation and maintenance in chronic dry eye disease

Substance P is a neuropeptide expressed by nerves and an array of cells that serves as a critical mediator of neuroinflammation. Our recent work has demonstrated that blocking the preferred receptor for substance P, neurokinin 1 receptor, effectively suppresses the induction of acute dry eye disease by preserving regulatory T-cell function, while inhibiting antigen-presenting cell maturation and subsequent generation of effector Th17 cells. Clinically, dry eye disease is a chronic disorder characterized by sustained ocular surface inflammation, which is mediated by long-lived memory Th17 cells demonstrated in our well-established chronic dry eye disease model. The present study aimed to further understand the function of substance P in the chronic phase of dry eye disease and its role in regulating the underlying pathogenic memory Th17. In vitro culture of effector T cells isolated from acute dry eye disease with substance P led to an enhanced conversion of effector Th17 to memory Th17, while culturing memory T cells isolated from chronic dry eye disease with substance P effectively preserved the memory Th17 cells. In contrast, the addition of a neurokinin 1 receptor antagonist in the cultures abolished the substance P-mediated effects. Furthermore, in vivo treatment with the neurokinin 1 receptor antagonist during the resolution phase of acute dry eye disease significantly suppressed memory Th17 generation, and treatment in the chronic phase of dry eye disease disrupted the maintenance of memory Th17. Taken together, our results demonstrate that increased expression of substance P promotes memory Th17 generation and maintenance in chronic dry eye disease, and thus blockade of substance P represents a novel promising memory Th17-targeting strategy in treating chronic ocular surface inflammation.

Genomics of Staphylococcus aureus and Enterococcus faecalis isolated from the ocular surface of dry eye disease sufferers

Ocular surface inflammatory disorders, such as dry eye, are becoming increasingly prevalent. Developing new treatment strategies targeting harmful bacteria could provide significant therapeutic benefits. The purpose of this study was to characterize the common ocular pathogen Staphylococcus aureus and the rarer endophthalmitis-associated species Enterococcus faecalis isolated from the ocular surface of dry eye disease patients in Norway. Together the 7 isolates (5 S. aureus and 2 E. faecalis) comprise the complete set of members of each species isolated in our previous study of the ocular microbiome of 61 dry eye sufferers. We aimed to investigate the pathogenic potential of these isolates in relation to ocular surface health. To this end, we used whole genome sequencing, multiplex PCR directed at virulence genes and antibiotic susceptibility tests encompassing clinically relevant agents. The E. faecalis isolates showed resistance to only gentamicin. S. aureus isolates displayed susceptibility to most of the tested antibiotics, except for two isolates which showed resistance to trimethoprim/sulfamethoxazole and three isolates which were resistant to ampicillin. Susceptibilities included sensitivity to several first-line antibiotics for treatment of ocular infections by these species. Thus, treatment options would be available if required. However, spontaneous resistance development to gentamicin and rifampicin occurred in some S. aureus which could be a cause for concern. Whole genome sequencing of the isolates showed genome sizes ranging from 2.74 to 2.83 Mbp for S. aureus and 2.86 Mbp for E. faecalis, which is typical for these species. Multilocus sequence typing and phylogenetic comparisons with previously published genomes, did not suggest the presence of eye-specific clusters for either species. Genomic analysis indicated a high probability of pathogenicity among all isolates included in the study. Resistome analysis revealed the presence of the beta-lactamase blaZ gene in all S. aureus isolates and the dfrG gene in two of them; while E. faecalis isolates carried the lsa(A) gene which confers intrinsic resistance to lincosamides and streptogramin A in this species. Screening for virulence factors revealed the presence of various pathogenicity associated genes in both S. aureus and E. faecalis isolates. These included genes coding for toxin production and factors associated with evading the host immune system. Some of the identified genes (tst, hylA & hylB) are suggested to be linked to the pathophysiology of dry eye disease. Lastly, the presence of specific S. aureus virulence genes was confirmed through multiplex PCR analysis.

Advancements in Ocular Therapy: A Review of Emerging Drug Delivery Approaches and Pharmaceutical Technologies

Eye disorders affect a substantial portion of the global population, yet the availability of efficacious ophthalmic drug products remains limited. This can be partly ascribed to a number of factors: (1) inadequate understanding of physiological barriers, treatment strategies, drug and polymer properties, and delivery systems; (2) challenges in effectively delivering drugs to the anterior and posterior segments of the eye due to anatomical and physiological constraints; and (3) manufacturing and regulatory hurdles in ocular drug product development. The present review discusses innovative ocular delivery and treatments, encompassing implants, liposomes, nanoparticles, nanomicelles, microparticles, iontophoresis, in situ gels, contact lenses, microneedles, hydrogels, bispecific antibodies, and gene delivery strategies. Furthermore, this review also introduces advanced manufacturing technologies such as 3D printing and hot-melt extrusion (HME), aimed at improving bioavailability, reducing therapeutic dosages and side effects, facilitating the design of personalized ophthalmic dosage forms, as well as enhancing patient compliance. This comprehensive review lastly offers insights into digital healthcare, market trends, and industry and regulatory perspectives pertaining to ocular product development.

Cellular Stress in Dry Eye Disease-Key Hub of the Vicious Circle

Disturbance or insufficiency of the tear film challenges the regulatory systems of the ocular surfaces. The reaction of the surfaces includes temporary mechanisms engaged in the preservation of homeostasis. However, strong or persisting challenges can lead to the potential exhaustion of the coping capacity. This again activates the vicious circle with chronic inflammation and autocatalytic deterioration. Hence, the factors challenging the homeostasis should be addressed in time. Amongst them are a varying osmolarity, constant presence of small lesions at the epithelium, acidification, attrition with mechanical irritation, and onset of pain and discomfort. Each of them and, especially when occurring simultaneously, impose stress on the coping mechanisms and lead to a stress response. Many stressors can culminate, leading to an exhaustion of the coping capacity, outrunning normal resilience. Reaching the limits of stress tolerance leads to the manifestation of a lubrication deficiency as the disease we refer to as dry eye disease (DED). To postpone its manifestation, the avoidance or amelioration of stress factors is one key option. In DED, this is the target of lubrication therapy, substituting the missing tear film or its components. The latter options include the management of secondary sequelae such as the inflammation and activation of reparative cascades. Preventive measures include the enhancement in resilience, recovery velocity, and recovery potential. The capacity to handle the external load factors is the key issue. The aim is to guard homeostasis and to prevent intercellular stress responses from being launched, triggering and invigorating the vicious circle. Considering the dilemma of the surface to have to cope with increased time of exposure to stress, with simultaneously decreasing time for cellular recovery, it illustrates the importance of the vicious circle as a hub for ocular surface stress. The resulting imbalance triggers a continuous deterioration of the ocular surface condition. After an initial phase of the reaction and adaption of the ocular surface to the surrounding challenges, the normal coping capacity will be exhausted. This is the time when the integrated stress response (ISR), a protector for cellular survival, will inevitably be activated, and cellular changes such as altered translation and ribosome pausing are initiated. Once activated, this will slow down any recovery, in a phase where apoptosis is imminent. Premature senescence of cells may also occur. The process of prematurization due to permanent stress exposures contributes to the risk for constant deterioration. The illustrated flow of events in the development of DED outlines that the ability to cope, and to recover, has limited resources in the cells at the ocular surface. The reduction in and amelioration of stress hence should be one of the key targets of therapy and begin early. Here, lubrication optimization as well as causal treatment such as the correction of anatomical anomalies (leading to anatomical dry eye) should be a prime intent of any therapy. The features of cellular stress as a key hub for the vicious circle will be outlined and discussed.

HDAC1/2 and HDAC3 play distinct roles in controlling adult Meibomian gland homeostasis

PURPOSE

To investigate the roles of HDAC1/2 and HDAC3 in adult Meibomian gland (MG) homeostasis.

METHODS

HDAC1/2 or HDAC3 were inducibly deleted in MG epithelial cells of adult mice. The morphology of MG was examined. Proliferation, apoptosis, and expression of MG acinus and duct marker genes, meibocyte differentiation genes, and HDAC target genes, were analyzed via immunofluorescence, TUNEL assay, and RNA in situ hybridization.

RESULTS

Co-deletion of HDAC1/2 in MG epithelium caused gradual loss of acini and formation of cyst-like structures in the central duct. These phenotypes required homozygous deletion of both HDAC1 and HDAC2, indicating that they function redundantly in the adult MG. Short-term deletion of HDAC1/2 in MG epithelium had little effect on meibocyte maturation but caused decreased proliferation of acinar basal cells, excessive DNA damage, ectopic apoptosis, and increased p53 acetylation and p16 expression in the MG. By contrast, HDAC3 deletion in MG epithelium caused dilation of central duct, atrophy of acini, defective meibocyte maturation, increased acinar basal cell proliferation, and ectopic apoptosis and DNA damage. Levels of p53 acetylation and p21 expression were elevated in HDAC3-deficient MGs, while the expression of the differentiation regulator PPARγ and the differentiation markers PLIN2 and FASN was downregulated.

CONCLUSIONS

HDAC1 and HDAC2 function redundantly in adult Meibomian gland epithelial progenitor cells and are essential for their proliferation and survival, but not for acinar differentiation, while HDAC3 is required to limit acinar progenitor cell proliferation and permit differentiation. HDAC1/2 and HDAC3 have partially overlapping roles in maintaining survival of MG cells.

Comparison of tear Matrix Metalloproteinase 9 (MMP-9) estimation with Schirmer's test in Ocular Surface Disorders

Background

Ocular surface disorder (OSD) is a vexed eye problem and a diagnostic conundrum. Diagnosis has traditionally depended upon symptoms and tests like Schirmer's, TBUT, staining with dyes, and tear meniscus height. Schirmer's test is the most popular. However, the test strips irritate with reflex tearing - producing false high results. Matrix Metalloproteinase 9 (MMP) in the tear is believed to be expressed by stressed epithelial cells of the corneal surface - a key pathology in dry eye disease. This study attempts to compare the results of Schirmer's test and MMP-9 so that the test can individually or severally add to a more definite diagnosis of dry eye disease.

Materials and methods

100 eyes of 50 symptomatic patients underwent MMP-9 estimation and were divided into two groups (MMP-9+ve and MMP-9-ve). They were then sub-grouped as per DEWS-2007 based on Schirmer test levels and Ocular Symptomatology Score (OSS). The two groups were compared for severity of dry eye based on Schirmer's test and OSS.

Results

Mean Schirmer's value was 12.85 (SD 7.07) for MMP-9+ve and 19.18 (SD 8.94) for MMP-9-ve patients. 80% of patients with severe dry eye and 55.6% of moderate dry eye patients were positive for MMP-9. 85% of the MMP-9 patients had OSS values of 2 or 3.

Discussion

A higher OSDI and positive MMP-9 were shown to be correlated in a statistically remarkable way (p<0.001). The OSDI values of 0-12 for 3/44 (6.8%) positive results, 13-22 for 2/8 (25%) positive results, 23-32 for 4/14 (28.6%) positive results, and 33-100 for 13/35 (37.1%) positive results all showed an increase in MMP-9 positivity along with a rise in the subjective severity of the illness.

Conclusion

MMP-9 compares well with Schirmer's values and DED categories based on Schirmer's. The result pointed towards the usefulness of this test in diagnosing patients who may have not yet manifested symptoms.

Preliminary study of cyclosporine A/Lifitegrast subconjunctival sustained-release drug membrane in the treatment of dry eyes

BACKGROUND

Dry eyes can cause discomfort. To treat dry eye disease, cyclosporine A (CsA) and Lifitegrast are two eye drugs approved by the U.S. Food and Drug Administration (FDA). However, frequent use of eye drops can be challenging and lead to poor compliance, especially in elderly patients. Therefore, this study aimed to develop a drug sustained-release vector and explore its therapeutic effect in animal models of dry eye.

METHODS

Firstly, drug membranes loaded with both CsA and Lifitegrast using a carrier called poly(lactate-co-ε-caprolactone) (P(LLA-CL)) were prepared and evaluated for their physicochemical properties, release behavior in vitro, and safety in vivo. Next, a rabbit dry eye model using a 0.1% benzalkonium chloride (BAC) solution was developed and treated by drug-loaded micro membranes. We observed and recorded conjunctival hyperemia, corneal staining, corneal edema, corneal neovascularization, conjunctival goblet cells and hematoxylin and eosin (H&E) staining. Finally, we detected the MUC5AC and MMP-9 by immunofluorescence staining and enzyme-linked immunosorbent assay (ELISA).

RESULTS

The composite film released both CsA and Lifitegrast for at least one month. Compared to the blank membrane group, conjunctival hyperemia, corneal fluorescein staining, corneal edema, corneal neovascularization and conjunctival goblet cells recovered faster in the drug membrane group, and the difference was statistically significant. At the molecular level, the drug membrane group showed an increase in mucin density and a significant anti-inflammatory effect.

CONCLUSIONS

The implantation of CsA/Lifitegrast loaded P(LLA-CL) membrane under the subconjunctival of the rabbit eye is safe. The study suggests that this subconjunctival administration could be developed into a minimally invasive delivery system to help patients with dry eye disease who require multiple daily eyedrops but have poor compliance.

Quantitative Assessment of Lid Margin Vascularity Using Swept-Source Optical Coherence Tomography Angiography

Purpose

To evaluate the ability of swept-source optical coherence tomography angiography (SS-OCTA) to assess lid margin vascularity.

Methods

This prospective, cross-sectional trial enrolled 125 participants, including 15 control subjects and 110 meibomian gland dysfunction (MGD) patients. Lid margin blood flow density (LMBFD) was obtained using SS-OCTA. LMBFD was assessed for repeatability in 54 of 125 participants and for reproducibility in 23 of 125 participants. The efficacy of LMBFD was validated in the 125 participants, who were divided into mild (n = 46), moderate (n = 42), and severe groups (n = 37) according to the lid margin vascularity severity shown in the slit-lamp photographs. Correlations between LMBFD and MG-related parameters, such as ocular surface disease index (OSDI), fluorescein tear break-up time (FTBUT), cornea fluorescein staining (CFS), lid margin score (LMS), and meibomian gland expressibility (ME), were analyzed in all 125 participants.

Results

Repeatability and reproducibility coefficients were satisfactorily high in the scan mode with a scan area of 6 mm × 6 mm (intraclass correlation coefficient [ICC] repeatability = 0.905; ICC reproducibility = 0.986) and a scan area of 9 mm × 9 mm (ICC repeatability = 0.888; ICC reproducibility = 0.988). The LMBFD gradually increased in the mild, moderate, and severe groups (P < 0.001). LMBFD was significant correlated with OSDI (r = 0.290, P = 0.001), FTBUT (r = -0.195, P = 0.030), CFS (r = 0.352, P < 0.001), ME (r = 0.191, P = 0.033), and LMS (r = 0.370, P < 0.001).

Conclusions

LMBFD may be a noninvasive, repeatable, reproducible, and efficient index for the quantitative evaluation of eyelid margin vascularity in the future.

Translational Relevance

We demonstrated that SS-OCTA has the potential to evaluate the eyelid margin vascularity in MGD patients and guide future treatment strategies in clinics.

Association of Systemic Markers of Inflammation with Signs and Symptoms of Dry Eye Disease and Sjogren's Syndrome in the Dry Eye Assessment and Management (DREAM©) Study

PURPOSE

To evaluate the possible role of systemic inflammation in dry eye disease (DED) via systemic inflammatory marker associations with DED signs and symptoms, and an analysis of a subgroup with Sjogren's Syndrome (SS).

METHODS

Participant serums were analyzed using line immunoassays (LIAs) for the presence of antibodies against 34 systemic inflammatory markers. Using the 2012 American College of Rheumatology definition, the 481 participants were categorized into group 1 (SS; n = 52), group 2 (autoimmune disease not including SS; n = 66), or group 3 (control, i.e. no autoimmune disease; n = 363).

RESULTS

3 markers were positive in ≥10% of participants: Ro52 (19.3%), Scl-70 (15.0%), CN-1A (14.2%). 2 markers were positively associated with symptoms: PM-Scl100 (p = 0.02), Sm (p = 0.009). 5 markers were positively associated with signs: U2SnRNP A', Ro52, La, DNA, Ro60. SS participants showed significantly higher positivity for 4 markers compared to participants with no autoimmune disease: PL-7 (p = 0.02), Ro52 (p < 0.0001), La (p < 0.0001), Ro60 (p < 0.0001). SS participants showed significantly higher positivity for 3 markers compared to participants with another autoimmune disease: Ro52 (p < 0.0001), La (p = 0.002), Ro60 (p < 0.0001).

CONCLUSIONS

This study did not show evidence of significant systemic inflammation in participants with moderate-to-severe DED, based on the markers tested. PM-Scl100 and Sm may be associated with more severe DED symptoms. U2SnRNP A', Ro52, La, DNA, and Ro60 may be associated with more severe ocular surface disease. Ro52 and PL-7 may be diagnostic markers for SS. Future research evaluating these relationships and their clinical significance is needed.

Efficacy of far infrared functional glasses in the treatment of meibomian gland dysfunction-related dry eye

Meibomian gland dysfunction (MGD)-related dry eye disease (DED) is a significant subtype of DED. In this research, we investigate the effectiveness of far infrared (FIR) functional glasses in the treatment of MGD-related DED. According to the TFO DEWS II diagnostic criteria, 61 eyes with MGD-related DED were included. All participants wore functional FIR glasses throughout the day for a period of 4 weeks and were followed up three times during the treatment. All subjects were followed up thoroughly in accordance with the DED clinical examination procedure. Ultimately, the treatment's impact was assessed. We found the Visual Analogue Scale and Ocular Surface Disease Index scores after FIR treatment were significantly lower than the baseline values (p < 0.05). Compared with the baseline, fluorescein tear breakup time and corneal fluorescein staining score after FIR treatment were significantly improved (p < 0.05). The eyelid margin signs, meibum quality, and meibomian gland expressibility after the 4-week treatment were significantly better than those at baseline (p < 0.05). We can see that wearing the FIR functional glasses significantly relieves the symptoms and signs of patients. We believe FIR therapy could be considered as a new method of MGD-related DED.

Idiopathic CD4 Lymphocytopenia: A Case Report and Literature Review

Idiopathic CD4 lymphocytopenia (ICL) is a rare condition where CD4 T cell counts are low, similar to advanced human immunodeficiency virus (HIV) infection but without acquired immunodeficiency syndrome (AIDS)-related symptoms. The cause is unknown, and theories suggest issues with T cell production, survival, migration, or immune system dysregulation. Diagnosis involves ruling out other causes of low CD4 T cells. Treatment is based on managing infections and may include immunomodulatory therapies, but evidence is limited. Clinical presentations vary widely, including infections, autoimmune disorders, and malignancies. This study explores challenges in diagnosing persistent fevers and lymphopenia, the role of medical history in treatment, HIV screening issues, UTI management in recurrent cases, and the importance of follow-up care for unresolved symptoms or abnormal lab results. This study utilized a case study approach, focusing on the detailed presentation, evaluation, and management of the patient. Data were collected from the patient's medical records, including laboratory tests. Relevant literature was reviewed to provide context and support for the discussion of diagnostic challenges and management strategies. This case highlights the importance of considering uncommon presentations of common infections in patients with complex medical histories. It underscores the need for thorough evaluation, including comprehensive medical history, diagnostic testing, and follow-up care, to ensure accurate diagnosis and appropriate management. By sharing this case, we aim to enhance the awareness and understanding of such presentations among healthcare providers, leading to improved patient care and outcomes.

Potential Benefits of Integrin αvβ3 Antagonists in a Mouse Model of Experimental Dry Eye

PURPOSE

The purpose of this study was to extensively evaluate the efficacy of integrin αvβ3 antagonists for the treatment of experimental dry eye (EDE).

METHODS

Vitronectin, an αvβ3 ligand, was used to induce tumor necrosis factor-α gene expression in human THP-1 macrophages. To induce EDE, C57BL/6 mice were housed in a low-humidity controlled environment chamber and injected subcutaneously with scopolamine for 7 days. Subsequently, αvβ3 antagonists, including RGDfD, c(RGDfD), c(RGDiD), c(RGDfK), ATN-161, SB273005, and cilengitide, were administered topically to EDE animals under controlled environment chamber conditions. Corneal epithelial damage in EDE was assessed by fluorescein staining. The density of conjunctival goblet cells and secretion of tears was measured by period acid-Schiff staining and phenol red-impregnated cotton threads, respectively. Inflammation markers, including tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-17A, and metalloproteinase (MMP)-9, in the pooled cornea and conjunctiva tissues were examined by real-time polymerase chain reaction.

RESULTS

The inhibitory effects of αvβ3 antagonists on the vitronectin-induced tumor necrosis factor-α gene expression and integrin-mediated inflammatory signaling were validated in THP-1 macrophages. αvβ3 antagonists ameliorated the impairment of the corneal epithelial barrier with varying therapeutic efficacies, compared with vehicle-treated mice. c(RGDfD) and c(RGDiD) significantly protected against goblet cell loss, tear reduction, and proinflammatory gene expression in EDE.

CONCLUSIONS

Topical applications of αvβ3 antagonists yield therapeutic benefits in EDE by promoting corneal epithelial defect healing and reducing inflammation. Antagonistic targeting αvβ3 may be a novel promising strategy to treat patients with dry eye disease.

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.

A latent profile analysis of tear cytokines and their association with severity of dry eye disease in the Dry Eye Assessment and Management (DREAM) study

This study is to identify subgroups of DED patients with different tear cytokine profiles and compare their DED symptoms and signs among subgroups. Baseline tear cytokines (IL-1β, IL-6, IL-8, IL-10, IL-17A, IFN-γ and TNF-α) were measured using a magnetic bead assay. DED symptoms were assessed by Ocular Surface Disease Index (OSDI) and signs were assessed by corneal and conjunctival staining, tear break-up time (TBUT), Schirmer's test, tear osmolarity and meibomian gland dysfunction (MGD). Latent profile analysis was performed to identify subgroups, and their scores of DED symptoms and signs were compared using generalized linear regression. Among 131 patients with total tear volume > 4 µl from both eyes, subgroup 1 (n = 23) significantly higher in IL-6 and IL-8 (all p < 0.001) and subgroup 2 (n = 108) significantly higher in IL-10 (p = 0.03), IL-17A (p < 0.001), and IFN-γ (p < 0.001). Both subgroups were similar in demographics and DED symptoms, but subgroup 1 had significantly more severe DED signs: higher conjunctival staining (3.38 vs. 2.69, p = 0.04), corneal staining (4.26 vs. 3.03, p = 0.03), lower Schirmer's test score (8.20 vs. 13.72, p < 0.001), and higher composite severity score of DED sign (0.62 vs. 0.45, p = 0.002). We identified two DED subgroups with different profiles of tear cytokines. Patients in these subgroups differed significantly in DED signs, supporting the inflammation's role in DED development and progression.

Association of Tear Cytokine Ratios with Symptoms and Signs of Dry Eye Disease: Biomarker Data from the Dry Eye Assessment and Management Study

PURPOSE

To assess the relationship between tear inflammatory cytokine ratios (CRs) and signs and symptoms of dry eye disease (DED) to investigate the possible use of tear CRs, which may better address the complexity of cytokine interactions than absolute cytokine levels, as a DED biomarker.

METHODS

Tear concentrations of IL-1b, IL-6, IL-8, IL-10, IL-17A, IFN-g, and TNF-a were measured using standardized procedures, as were DED signs (corneal and conjunctival staining scores, tear break-up time, Schirmer test, Meibomian gland plugging, tear osmolarity, composite sign severity score) and symptoms [Ocular Surface Disease Index (OSDI)]. Ratios between pro-inflammatory (IL-1b, IL-8, IL-17A, IFN-g, and TNF-a) and anti-inflammatory (IL-10) cytokines were calculated. Given its opposing roles in inflammation, IL-6 was tested as both a pro- and anti-inflammatory cytokine. Correlations between CR and DED symptoms and signs were calculated using Spearman correlation coefficients (rho).

RESULTS

At baseline, 131 patients, 80.2% female and mean age 54.2 years (SD 14.1, range 20-82), from 10 sites of the Dry Eye Assessment and Management study had sufficient tear volumes ≥4 μL for analysis. IL-6:IL-10, IL-8:IL-10, and TNF-a:IL-10 had some significant correlations, mostly with conjunctival or corneal staining or the composite sign severity score (IL-8:IL-10 and conjunctival staining: rho = 0.19, p = 0.03; IL-6:IL-10 and corneal staining: rho = 0.31, p < 0.001; IL-8:IL-10 and corneal staining: rho = 0.21, p = 0.01; IL-6:IL-10 and composite sign severity score: rho = 0.26, p = 0.003; IL-8:IL-10 and composite sign severity score: rho = 0.26, p = 0.003; TNF-a:IL-10 and corneal staining: rho = 0.29, p < 0.001; TNF-a:IL-10 and Schirmer test: rho = -0.23, p = 0.009). CRs had no significant correlation with DED symptoms. All significant correlations using IL-6 in the denominator (anti-inflammatory) produced counterintuitive results based on clinical understanding of the disease.

CONCLUSIONS

Pro- to anti-inflammatory CR was weakly correlated with some DED signs and not with symptoms, as measured by OSDI. Future studies in different dry eye populations are needed and should address sampling biases and tear collection techniques.

Therapeutic Potential of Crocin and Nobiletin in a Mouse Model of Dry Eye Disease: Modulation of the Inflammatory Response and Protection of the Ocular Surface

Background

Dry eye disease (DED) is a multifactorial condition characterized by ocular surface inflammation, tear film instability, and corneal epithelial damage. Current treatments often provide temporary relief without addressing the underlying inflammatory mechanisms.

Objectives

This study examined the therapeutic potential of crocin and nobiletin, two naturally derived compounds with well-known antioxidant and anti-inflammatory properties, in a mouse model of DED induced by lacrimal gland excision (LGE).

Methods

Thirty female Balb/c mice were divided into five groups (n = 6 each): Control (sham surgery), untreated DED, nobiletin-treated DED (32.75 µM), crocin-treated DED (34 µM), and 1% betamethasone-treated DED. Treatments were administered three times daily for 28 days. Ocular tissues were evaluated using Hematoxylin and Eosin (H&E) staining and fluorescein staining. Conjunctival inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1 beta (IL-1β), and tumor necrosis factor-alpha (TNF-α), were measured by enzyme-linked immunosorbent assay (ELISA).

Results

Histological analysis showed that the crocin and nobiletin treatment groups exhibited reduced epithelial disruption, keratinization, and inflammatory cell infiltration compared to the untreated DED group. The ELISA assay revealed that both compounds efficiently inhibited the production of the pro-inflammatory cytokines IL-6, TNF-α, and IL-1β, which are key mediators of DED pathogenesis. Fluorescein staining further confirmed the protective impact of crocin and nobiletin on corneal epithelial integrity. Moreover, the anti-inflammatory and epithelial-preserving effects of these compounds were comparable to those of the corticosteroid betamethasone.

Conclusions

Overall, these findings suggest that crocin and nobiletin have therapeutic potential for DED management by modulating inflammatory responses and enhancing ocular surface healing. These naturally derived compounds offer promising avenues for the development of safer and more effective treatments for this challenging condition. However, further investigations, including clinical trials, are essential to elucidate the underlying mechanisms of action and optimize therapeutic approaches.

The Combined Impact of Intense Pulsed Light Combined and 3% Diquafosol Ophthalmic Solution on Evaporative Dry Eye: A Randomized Control Study

INTRODUCTION

The primary objective of this study is to assess whether the combination of intense pulsed light (IPL) with 3% diquafosol (DQS) ophthalmic solution is more effective than intense pulsed light in alleviating signs and symptoms of dry eye disease (DED).

METHODS

This randomized study included 66 participants with evaporative dry eye (EDE) who received IPL + DQS therapy (n = 44 eyes), IPL therapy (n = 44 eyes), or sham therapy (n = 44 eyes). All participants were examined at baseline (D0), day 14 (D14), and day 28 (D28) for non-invasive break-up time (NITBUT), tear-film lipid layer (TFLL), corneal conjunctival staining (CS), meibomian gland quality (MGQ), meibomian gland expression (MGEx), and ocular surface disease index (OSDI).

RESULTS

At day 28, comparison among the IPL + DQS therapy, IPL therapy, and sham therapy found significant differences in the mean NITBUT (12.03 ± 1.27 versus 10.47 ± 3.48 versus 4.57 ± 0.46; p < 0.001), TFLL (2.09 ± 0.29 versus 2.27 ± 0.45 versus 2.89 ± 0.65; p < 0.001), CS (1.43 ± 0.82 versus 1.93 ± 1.32 versus 3.52 ± 1.00; p < 0.001), MGQ (1.55 ± 0.66 versus 1.91 ± 0.77 versus 2.66 ± 0.53; p < 0.001), MGEx (1.27 ± 0.45 versus 1.75 ± 0.44 versus 2.41 ± 0.50; p < 0.001), and OSDI score (19.36 ± 7.01 versus 24.77 ± 4.68 versus 42.61 ± 7.49; p < 0.001); significant improvements in NITBUT, TFLL, CS, MGQ, MGEx, and OSDI were found in the IPL + DQS therapy and IPL therapy, while the sham therapy had no significant improvements.

CONCLUSION

Combining 3% diquafosol ophthalmic solution with intense pulsed light was superior to IPL therapy alone in relieving the signs and symptoms of patients with severe evaporative DED.

TRIAL REGISTRATION

Clinical Trials Identifier: NCT05694026.

Ocular surface microbiota dysbiosis contributes to the high prevalence of dry eye disease in diabetic patients

People with diabetes mellitus (DM) are at an increased risk for developing dry eye disease (DED). However, the mechanisms underlying this phenomenon remain unclear. Recent studies have found that the ocular surface microbiota (OSM) differs significantly between patients with DED and healthy people, suggesting that OSM dysbiosis may contribute to the pathogenesis of DED. This hypothesis provides a new possible explanation for why diabetic patients have a higher prevalence of DED than healthy people. The high-glucose environment and the subsequent pathological changes on the ocular surface can cause OSM dysbiosis. The unbalanced microbiota then promotes ocular surface inflammation and alters tear composition, which disturbs the homeostasis of the ocular surface. This "high glucose-OSM dysbiosis" pathway in the pathogenesis of DED with DM (DM-DED) is discussed in this review.

Optical Coherence Tomography Angiography for Evaluation of Conjunctival Vessels in Dry Eyes

Objective

This study aimed to evaluate conjunctival vessels in patients with dry eye disease (DED) using optical coherence tomography angiography (OCTA).

Methods

This was a cross-sectional, observational clinical study. Twenty-three eyes of 18 patients with DED and 28 eyes of 23 healthy controls were included for examination in this study. The evaluation included the application of an Ocular Surface Disease Index Questionnaire, Schirmer Basic Secretion Test, and anterior OCTA targeting the temporal conjunctiva. AngioTool software was used to quantify the total vessel length and vessel density in the 3 × 3 mm temporal region of interest.

Results

Blood vessel density measurements were compared across the OCTA systems. The total vessel length within the conjunctiva of the DED group (4799.34 ± 834.36) exceeded that of the control eye (3864.89 ± 1455.70) group (P < 0.05). However, the difference in vessel density between the two groups was not statistically significant.

Conclusion

Measurement and analysis of conjunctival blood vessels using OCTA exhibited robust repeatability. In dry eyes, the total number of conjunctival blood vessels increased in accordance with disease severity. Hypoxia of conjunctival tissue may be an important cause of dry eye disease.

Influence of Vitreoretinal Surgery on Ocular Surface Dynamics Using Keratograph 5M

PURPOSE

To evaluate changes of ocular surface dynamics using Keratograph 5M for 3 months after vitreoretinal surgery.

METHODS

Eighty-three patients were divided into three groups: phacoemulsification group, vitrectomy group, and combined group. Keratograph 5M was performed for all patients at 1 week, 1 month, and 3 months after the surgery. Ocular surface dynamics parameters measured by Keratograph 5M, including noninvasive keratograph first tear film breakup time (NifBUT), noninvasive keratograph average tear film breakup time (NiaBUT), and tear meniscus height (TMH) were compared among the three groups over time.

RESULTS

The mean age of all patients (46 men and 37 women) was 62.2 ± 8.4 years. NifBUT and NiaBUT were significantly decreased at 1 week after surgery compared to those at baseline in all three groups (all p < 0.001). NifBUT and NiaBUT in the phacoemulsification group almost recovered to the preoperative level, while those in the vitrectomy group and the combined group were still significantly less than those at baseline. NifBUT and NiaBUT in the phacoemulsification group were significantly longer than those in the vitrectomy group and the combined group at 3 months. After 1 week, TMHs were significantly higher in the vitrectomy group (p = 0.001) and the combined group (p = 0.022) than in the phacoemulsification group, while TMHs were significantly less in the vitrectomy group (p = 0.010) and the combined group (p < 0.001) than in the phacoemulsification group at 3 months after surgery.

CONCLUSIONS

These results suggest that vitreoretinal surgery could induce alteration of ocular surface dynamics for 3 months. The vitrectomy group and the combined group showed tear film instability compared to the cataract surgery alone group. Patients who underwent vitreoretinal surgery experienced more severe dry eye syndrome symptoms than those who underwent cataract surgery. Thus, managing dry eye syndrome after vitreoretinal surgery should be considered important for patients.

Combining MSC Exosomes and Cerium Oxide Nanocrystals for Enhanced Dry Eye Syndrome Therapy

Dry eye syndrome (DES) is a prevalent ocular disorder involving diminishe·d tear production and increased tear evaporation, leading to ocular discomfort and potential surface damage. Inflammation and reactive oxygen species (ROS) have been implicated in the pathophysiology of DES. Inflammation is one core cause of the DES vicious cycle. Moreover, there are ROS that regulate inflammation in the cycle from the upstream, which leads to treatment failure in current therapies that merely target inflammation. In this study, we developed a novel therapeutic nanoparticle approach by growing cerium oxide (Ce) nanocrystals in situ on mesenchymal stem cell-derived exosomes (MSCExos), creating MSCExo-Ce. The combined properties of MSCExos and cerium oxide nanocrystals aim to target the "inflammation-ROS-injury" pathological mechanism in DES. We hypothesized that this approach would provide a new treatment option for patients with DES. Our analysis confirmed the successful in situ crystallization of cerium onto MSCExos, and MSCExo-Ce displayed excellent biocompatibility. In vitro and in vivo experiments have demonstrated that MSCExo-Ce promotes corneal cell growth, scavenges ROS, and more effectively suppresses inflammation compared with MSCExos alone. MSCExo-Ce also demonstrated the ability to alleviate DES symptoms and reverse pathological alterations at both the cellular and tissue levels. In conclusion, our findings highlight the potential of MSCExo-Ce as a promising therapeutic candidate for the treatment of DES.

Recent advances in drug treatments for dry eye disease

INTRODUCTION

Dry eye disease (DED) is a common ocular condition with a significant impact on patients' quality of life. Conventional treatments include behavioral changes, tear substitutes, and anti-inflammatory agents; however, recent advances in the understanding of DED pathogenesis have opened the way to the development of novel treatment strategies able to target several pathways involved in the onset and persistence of DED.

AREAS COVERED

Literature search was conducted on PubMed and Scopus around the term 'dry eye disease' and others involving its pathophysiology and therapeutic strategy. The primary focus was on recent drugs approved by FDA or under investigation in phase 3 clinical trials. Google and ClinicalTrials.gov were used for obtaining information about the status of FDA approval and ongoing clinical trials.

EXPERT OPINION

Due to its multifaced pathogenesis, DED management is often challenging, and patients' needs are frequently unmet. Recently, several novel treatments have been either FDA-approved or studied in late-phase trials. These novel drugs target-specific biological components of the ocular surface and reduce inflammation and ocular pain. Additionally, new drug delivery systems allow for increased bioavailability, improve effective dosing, and minimize ocular side effects. These advances in drug therapies show real promise for better management of DED patients.

Association of Ocular Surface Immune Cells With Dry Eye Signs and Symptoms in the Dry Eye Assessment and Management (DREAM) Study

Purpose

Dry eye disease (DED) is a multifactorial, heterogeneous disease of the ocular surface with one etiology being ocular surface inflammation. Studies using animal models demonstrate the role of ocular surface immune cells in the inflammatory pathway leading to DED, but few have evaluated humans. This study described the white blood cell population from the ocular surface of patients with DED and assessed its association with DED signs and symptoms in participants of the Dry Eye Assessment and Management (DREAM) study.

Methods

Participants were assessed for symptoms using the Ocular Surface Disease Index, signs via corneal staining, conjunctival staining, tear break-up time, and Schirmer test, and Sjögren's syndrome (SS) based on the 2012 American College of Rheumatology classification criteria. Impression cytology of conjunctival cells from each eye was evaluated using flow cytometry: T cells, helper T cells (Th), regulatory T cells (Tregs), cytotoxic T cells, and dendritic cells.

Results

We assessed 1049 eyes from 527 participants. White blood cell subtype percentages varied widely across participants. Significant positive associations were found for Th and conjunctival staining (mean score of 2.8 for 0% Th and 3.1 for >4.0% Th; P = 0.007), and corneal staining (mean score of 3.5 for 0% Th and 4.3 for >4.0% Th; P = 0.01). SS was associated with higher percent of Tregs (median 0.1 vs. 0.0; P = 0.01).

Conclusions

Th were associated with more severe conjunctival and corneal staining, possibly indicating their role in inflammation leading to damage of the ocular surface. There is no consistent conclusion about Tregs in SS, but these results support that Tregs are elevated in SS.

Immunoglobulin A levels and its correlation with neutrophil-to-lymphocyte ratio as inflammatory biomarkers for dry eye disease in type 2 diabetes: a retrospective study

Background

The neutrophil-to-lymphocyte ratio (NLR) and immunoglobulin A (IgA) level are commonly used as biomarkers for inflammation. Patients with type 2 diabetes (T2D) may experience an imbalance of tear film and inflammation, which can result in dry eye disease (DED). This study aimed to assess the levels of IgA and explore its correlation with the NLR as potential inflammatory biomarkers for dry eye disease in patients with T2D.

Methods

A retrospective study was conducted at the cornea clinic and diabetes centre of King Abdulaziz Medical City (Jeddah, Saudi Arabia). The study included patients with DED and the number of available T2D-DED patients determined the sample size. Neutrophil, lymphocyte, IgA and CRP (C-reactive protein) laboratory values were obtained from medical records and correlational analyses were performed.

Results

The study included 85 patients with an average age of 54 ± 14.4 years for the DED group (n=32) and 62 ± 13.9 years for the T2D-DED group (n=53). The age difference between the two groups was statistically significant (p 0.0001). The NLR values of the T2D-DED and DED groups were 3.203 ± 0.66 and 2.406 ± 0.46, respectively, with no significant difference (p<0.285). Similarly, there were no significant differences in neutrophil and lymphocyte values between the two groups. The IgA levels showed no significant variation between T2D-DED and DED groups (p<0.364). Spearman's correlation analysis in the DED group showed a significant negative correlation between IgA and lymphocyte (p=0.011; r= - 0.471) values and significant positive correlations between IgA and neutrophil (p=0.014; r=0.309) and NLR (p=0.052; r= - 0.283) values. In the T2D-DED group, a significant correlation was found between IgA and CRP values (p=0.032; r=0.33).

Conclusion

Although diabetic patients may exhibit higher levels of NLR and IgA that correlate with disease severity, our study did not find significant differences in NLR and IgA values between the two groups. These findings may guide future research and enhance understanding of the disease's underlying mechanisms.

MicroRNA-146a negatively regulates inflammation via the IRAK1/TRAF6/NF-κB signaling pathway in dry eye

Inflammation is a key factor in the pathogenesis of dry eye disease (DED). We aimed to investigate the role of microRNA-146a (miR-146a) in regulating corneal inflammation in a mouse model of benzalkonium chloride (BAC)-induced dry eye and the TNF-α-induced NF-κB signaling pathway in human corneal epithelial cells (HCECs). A mouse model of dry eye was established by administering with BAC to BALB/c mice, and the expression of TNF-α, IL-1β, IL-6, IL-8, cyclooxygenase 2 (COX2), interleukin-1 receptor-associated kinase 1 (IRAK1) and TNF receptor-associated factor 6 (TRAF6) in the corneas of dry eye model mice was significantly increased; this was accompanied by the upregulation of miR-146a and activation of the NF-κB pathway. In vitro, TNF-α induced miR-146a expression in HCECs, while the NF-κB inhibitor SC-514 reduced the expression of miR-146a. Overexpression of miR-146a decreased the expression of IRAK1 and TRAF6, which have been identified as targets of miR-146a. Furthermore, overexpression of miR-146a suppressed NF-κB p65 translocation from the cytoplasm to the nucleus. Moreover, overexpression of miR-146a attenuated the TNF-α-induced expression of IL-6, IL-8, COX2 and intercellular adhesion molecule 1 (ICAM1), while inhibition of miR-146a exerted the opposite effect. Our results suggest that miR-146a mediates the inflammatory response in DED. MiR-146a negatively regulates inflammation in HCECs through the IRAK1/TRAF6/NF-κB pathway, and this may serve as a potential therapeutic approach for the treatment of DED.

NLRP3 Inflammasome as a Potential Therapeutic Target in Dry Eye Disease

Dry eye disease (DED) is a multifactorial ocular surface disorder arising from numerous interrelated underlying pathologies that trigger a self-perpetuating cycle of instability, hyperosmolarity, and ocular surface damage. Associated ocular discomfort and visual disturbance contribute negatively to quality of life. Ocular surface inflammation has been increasingly recognised as playing a key role in the pathophysiology of chronic DED. Current readily available anti-inflammatory agents successfully relieve symptoms, but often without addressing the underlying pathophysiological mechanism. The NOD-like receptor protein-3 (NLRP3) inflammasome pathway has recently been implicated as a key driver of ocular surface inflammation, as reported in pre-clinical and clinical studies of DED. This review discusses the intimate relationship between DED and inflammation, highlights the involvement of the inflammasome in the development of DED, describes existing anti-inflammatory therapies and their limitations, and evaluates the potential of the inflammasome in the context of the existing anti-inflammatory therapeutic landscape as a therapeutic target for effective treatment of the disease.

Lactobacillus fermentum HY7302 Improves Dry Eye Symptoms in a Mouse Model of Benzalkonium Chloride-Induced Eye Dysfunction and Human Conjunctiva Epithelial Cells

(1) We investigated the effects of the Lactobacillus fermentum HY7302 (HY7302) in a mouse model of benzalkonium chloride (BAC)-induced dry eye, and the possibility of using HY7302 as a food supplement for preventing dry eye. (2) The ocular surface of Balb/c mice was exposed to 0.2% BAC for 14 days to induce dry eye (n = 8), and the control group was treated with the same amount of saline (n = 8). HY7302 (1 × 10⁹ CFU/kg/day, 14 days, n = 8) was orally administered daily to the mice, and omega-3 (200 mg/kg/day) was used as a positive control. To understand the mechanisms by which HY7302 inhibits BAC-induced dry eye, we performed an in vitro study using a human conjunctival cell line (clone-1-5c-4). (3) The probiotic HY7302 improved the BAC-induced decreases in the corneal fluorescein score and tear break-up time. In addition, the lactic acid bacteria increased tear production and improved the detached epithelium. Moreover, HY7302 lowered the BAC-induced increases in reactive oxygen species production in a conjunctival cell line and regulated the expression of several apoptosis-related factors, including phosphorylated protein kinase B (AKT), B-cell lymphoma protein 2 (Bcl-2), and activated caspase 3. Also, HY7302 alleviated the expression of pro-inflammatory cytokines, such as interleukin-1β (IL-1β), IL-6, and IL-8, and also regulated the matrix metallopeptidase-9 production in the conjunctival cell line. (4) In this study, we showed that L. fermentum HY7302 helps prevent dry eye disease by regulating the expression of pro-inflammatory and apoptotic factors, and could be used as a new functional food composition to prevent dry eye disease.

Association of Tear Cytokine Concentrations with Symptoms and Signs of Dry Eye Disease: Baseline Data from the Dry Eye Assessment and Management (DREAM) Study

PURPOSE

To describe tear concentrations of IL-1β, Il-6, IL-8, IL-10, IL-17A, IFNγ and TNFα in tears, collected by microcapillaries, and their correlation with symptoms and signs in subjects with dry eye disease (DED) in the DREAM Study.

METHODS

Cytokine levels of patients with moderate to severe DED were determined using a magnetic bead assay. Scores for Ocular Surface Disease Index, corneal and conjunctival staining, tear break-up time (TBUT), and Schirmer's test were obtained using standardized procedures. Associations of cytokines with each other and signs/symptoms were assessed with Spearman correlation coefficients (r).

RESULTS

Assay results from 131 patient samples from 10 sites with tear volumes ≥ 4 ul were analyzed. Cytokine concentrations did not correlate with each other in a generally acknowledged pro-inflammatory/anti-inflammatory pattern, such as proinflammatory IL-17A and IFNγ were not inversely correlated to anti-inflammatory cytokine IL-10, and cytokines did not correlate with DED symptoms. Lower corneal staining was correlated with higher concentrations of IL-17A (r= -0.24, p = 0.006), IL-10 (r= -0.25, p = 0.005) and IFNγ (r= -0.33, p = 0.0001). Higher concentrations of IFNγ were associated with lower conjunctival staining (r= -0.18, p = 0.03). Higher concentrations of IL-17A were associated with higher TBUT scores (r = 0.19 p = 0.02).

CONCLUSIONS

Cytokines IL-10, IL-17A and IFNγ were highly correlated with each other but weakly correlated with some DED signs. No key cytokines or definitive expression patterns were identified in this study of moderate to severe DED patients. Further studies addressing various biases, including methodological and sampling biases, and standardization of methodology for inter-laboratory consistency are needed to confirm and establish pathological and clinical relevance of tear cytokines in DED.

Identifying Meibomian Gland Dysfunction Biomarkers in a Cohort of Patients Affected by DM Type II

(1) Background: Meibomian gland dysfunction (MGD) among patients with diabetes mellitus (DM) is a common manifestation of dry eye syndrome (DES). (2) Methods: The purpose of this study is to identify clinical parameters and biomarkers useful to improve the follow-up and the treatment of these patients. We have used an ocular surface disease index (OSDI) questionnaire, Schirmer test I/II, tear film break-up time (TF-BUT), fluorescein plus lissamine green staining, Marx's line (ML), and meibomian gland (MGs) morphology using Sirius^® Topographer (CSO, Costruzione Strumenti Oftalmici, Florence, Italy). Blood sample analysis included glucose, glycated hemoglobin, lipid profile, cortisol, dehydroepiandrosterone sulfate (DHEA-S), androstenedione (ASD) and testosterone. (3) Results: Cortisol and ASD were positively correlated with an increase of MG tortuosity, and an Increased level of triglycerides was associated with a reduction of MGs length. DHEAS levels lowered with age and were associated with ocular surface staining. (4) Conclusions: Future studies, perhaps including meibum lipid analysis and tear cytokine levels, may also further elucidate the connection between these parameters, MG architecture and function.

Expression of Androgen and Estrogen Receptors in the Human Lacrimal Gland

Lacrimal gland dysfunction causes dry eye disease (DED) due to decreased tear production. Aqueous-deficient DED is more prevalent in women, suggesting that sexual dimorphism of the human lacrimal gland could be a potential cause. Sex steroid hormones are a key factor in the development of sexual dimorphism. This study aimed to quantify estrogen receptor (ER) and androgen receptor (AR) expression in the human lacrimal gland and compare it between sexes. RNA was isolated from 35 human lacrimal gland tissue samples collected from 19 cornea donors. AR, ERα, and ERβ mRNA was identified in all samples, and their expression was quantified using qPCR. Immunohistochemical staining was performed on selected samples to evaluate protein expression of the receptors. ERα mRNA expression was significantly higher than the expression of AR and ERβ. No difference in sex steroid hormone (SSH) receptor mRNA expression was observed between sexes, and no correlation was observed with age. If ERα protein expression is found to be concordant with mRNA expression, it should be investigated further as a potential target for hormone therapy of DED. Further research is needed to elucidate the role of sex steroid hormone receptors in sex-related differences of lacrimal gland structure and disease.

Rodent models for dry eye syndrome: Standardization using benzalkonium chloride and scopolamine hydrobromide

Dry eye disease is a highly prevalent ocular condition that significantly affects the quality of life and presents a major challenge in ophthalmology. Animal models play a crucial role in investigating the pathophysiology and developing effective treatments. The goal of this study was to compare and standardize two dry eye disease rodent models and explore their recovery aspects. We have standardized benzalkonium chloride and scopolamine-induced dry eye disease models which represents two different classes of the dry eye i.e., evaporative dry eye and aqueous deficient dry eye, respectively. After the development of dry eye conditions, a self-recovery period of seven days was granted to assess the reversal of the induced changes. The dry eye condition was assessed by measuring tear volume, corneal slit lamp imaging, and histological examination of the cornea, the lacrimal and the harderian gland. The study indicated the development of chronic inflammation of the cornea and lacrimal gland in the case of benzalkonium after five days of the treatment, while the scopolamine treated group showed chronic inflammation of the lacrimal gland after five days and corneal inflammation after seven days of administration. The recovery study suggested that after discontinuation of inducing agent, the dry eye symptoms were still persistent suggesting the utility of the model in evaluating dry eye treatments. The study highlights the comparative changes in both models along with recovery which can serve as a base for drug discovery and development against dry eye disease.

Dry Eye Disease: What Is the Role of Vitamin D?

Dry eye disease (DED) is a multifactorial condition resulting from reduced tear secretion from the lacrimal glands, increased tear water evaporation or the production of poor-quality tears. Such tear instability can lead to inflammation and damage of the ocular surface, as well as to abnormal nociception. Historically, tear substitutes and corticosteroids have been the bastion of DED therapy, but a substantial number of patients still suffer from residual symptoms even after being treated with traditional treatments. Aiming to find safe and effective alternative therapies, recent efforts have been focused on the role of vitamin D in the cellular physiology of the eye. Possibly because of its positive effect in modulating the immune and inflammatory responses, the systemic supplementation of vitamin D seems, indeed, to be an effective therapeutic strategy, especially, but not only, for patients affected by DED that does not respond to conventional treatments. In this context, this review focuses on the literature reporting on the pathogenesis and treatment of DED, with a special emphasis on the recent investigations reporting on the potential role of the systemic administration of vitamin D as a therapeutic approach in the management of such condition.