The Immunological Basis of Dry Eye Disease and Current Topical Treatment Options

Advances in development of exosomes for ophthalmic therapeutics

Exosomes contain multiple bioactive molecules and maintain the connection between cells. Recent advances in exosome-based therapeutics have witnessed unprecedented opportunities in treating ophthalmic diseases, including traumatic diseases, autoimmune diseases, chorioretinal diseases and others. Utilization of exosomes as delivery vectors to encapsulate both drugs and therapeutic genes could yield higher efficacy and avoid the unnecessary immune responses. However, exosome-based therapies also come with some potential ocular risks. In this review, we first present a general introduction to exosomes. Then we provide an overview of available applications and discuss their potential risks. Moreover, we review recently reported exosomes as delivery vectors for ophthalmic diseases. Finally, we put forward future perspectives to grapple with its translation and underlying issues.

Impact of Exposomes on Ocular Surface Diseases

Ocular surface diseases (OSDs) are significant causes of ocular morbidity, and are often associated with chronic inflammation, redness, irritation, discomfort, and pain. In severe OSDs, loss of vision can result from ocular surface failure, characterised by limbal stem cell deficiencies, corneal vascularisation, corneal opacification, and surface keratinisation. External and internal exposomes are measures of environmental factors that individuals are exposed to, and have been increasingly studied for their impact on ocular surface diseases. External exposomes consist of external environmental factors such as dust, pollution, and stress; internal exposomes consist of the surface microbiome, gut microflora, and oxidative stress. Concerning internal exposomes, alterations in the commensal ocular surface microbiome of patients with OSDs are increasingly reported due to advancements in metagenomics using next-generation sequencing. Changes in the microbiome may be a consequence of the underlying disease processes or may have a role in the pathogenesis of OSDs. Understanding the changes in the ocular surface microbiome and the impact of various other exposomes may also help to establish the causative factors underlying ocular surface inflammation and scarring, the hallmarks of OSDs. This review provides a summary of the current evidence on exposomes in various OSDs.

Congenital aniridia beyond black eyes: From phenotype and novel genetic mechanisms to innovative therapeutic approaches

Congenital PAX6-aniridia, initially characterized by the absence of the iris, has progressively been shown to be associated with other developmental ocular abnormalities and systemic features making congenital aniridia a complex syndromic disorder rather than a simple isolated disease of the iris. Moreover, foveal hypoplasia is now recognized as a more frequent feature than complete iris hypoplasia and a major visual prognosis determinant, reversing the classical clinical picture of this disease. Conversely, iris malformation is also a feature of various anterior segment dysgenesis disorders caused by PAX6-related developmental genes, adding a level of genetic complexity for accurate molecular diagnosis of aniridia. Therefore, the clinical recognition and differential genetic diagnosis of PAX6-related aniridia has been revealed to be much more challenging than initially thought, and still remains under-investigated. Here, we update specific clinical features of aniridia, with emphasis on their genotype correlations, as well as provide new knowledge regarding the PAX6 gene and its mutational spectrum, and highlight the beneficial utility of clinically implementing targeted Next-Generation Sequencing combined with Whole-Genome Sequencing to increase the genetic diagnostic yield of aniridia. We also present new molecular mechanisms underlying aniridia and aniridia-like phenotypes. Finally, we discuss the appropriate medical and surgical management of aniridic eyes, as well as innovative therapeutic options. Altogether, these combined clinical-genetic approaches will help to accelerate time to diagnosis, provide better determination of the disease prognosis and management, and confirm eligibility for future clinical trials or genetic-specific therapies.

The multifunctional human ocular melanocortin system

Immune privilege in the eye involves physical barriers, immune regulation and secreted proteins that together limit the damaging effects of intraocular immune responses and inflammation. The neuropeptide alpha-melanocyte stimulating hormone (α-MSH) normally circulates in the aqueous humour of the anterior chamber and the vitreous fluid, secreted by iris and ciliary epithelium, and retinal pigment epithelium (RPE). α-MSH plays an important role in maintaining ocular immune privilege by helping the development of suppressor immune cells and by activating regulatory T-cells. α-MSH functions by binding to and activating melanocortin receptors (MC1R to MC5R) and receptor accessory proteins (MRAPs) that work in concert with antagonists, otherwise known as the melanocortin system. As well as controlling immune responses and inflammation, a broad range of biological functions is increasingly recognised to be orchestrated by the melanocortin system within ocular tissues. This includes maintaining corneal transparency and immune privilege by limiting corneal (lymph)angiogenesis, sustaining corneal epithelial integrity, protecting corneal endothelium and potentially enhancing corneal graft survival, regulating aqueous tear secretion with implications for dry eye disease, facilitating retinal homeostasis via maintaining blood-retinal barriers, providing neuroprotection in the retina, and controlling abnormal new vessel growth in the choroid and retina. The role of melanocortin signalling in uveal melanocyte melanogenesis however remains unclear compared to its established role in skin melanogenesis. The early application of a melanocortin agonist to downregulate systemic inflammation used adrenocorticotropic hormone (ACTH)-based repository cortisone injection (RCI), but adverse side effects including hypertension, edema, and weight gain, related to increased adrenal gland corticosteroid production, impacted clinical uptake. Compared to ACTH, melanocortin peptides that target MC1R, MC3R, MC4R and/or MC5R, but not adrenal gland MC2R, induce minimal corticosteroid production with fewer adverse systemic effects. Pharmacological advances in synthesising MCR-specific targeted peptides provide further opportunities for treating ocular (and systemic) inflammatory diseases. Following from these observations and a renewed clinical and pharmacological interest in the diverse biological roles of the melanocortin system, this review highlights the physiological and disease-related involvement of this system within human eye tissues. We also review the emerging benefits and versatility of melanocortin receptor targeted peptides as non-steroidal alternatives for inflammatory eye diseases such as non-infectious uveitis and dry eye disease, and translational applications in promoting ocular homeostasis, for example, in corneal transplantation and diabetic retinopathy.

Recent Advances of Ocular Drug Delivery Systems: Prominence of Ocular Implants for Chronic Eye Diseases

Chronic ocular diseases can seriously impact the eyes and could potentially result in blindness or serious vision loss. According to the most recent data from the WHO, there are more than 2 billion visually impaired people in the world. Therefore, it is pivotal to develop more sophisticated, long-acting drug delivery systems/devices to treat chronic eye conditions. This review covers several drug delivery nanocarriers that can control chronic eye disorders non-invasively. However, most of the developed nanocarriers are still in preclinical or clinical stages. Long-acting drug delivery systems, such as inserts and implants, constitute the majority of the clinically used methods for the treatment of chronic eye diseases due to their steady state release, persistent therapeutic activity, and ability to bypass most ocular barriers. However, implants are considered invasive drug delivery technologies, especially those that are nonbiodegradable. Furthermore, in vitro characterization approaches, although useful, are limited in mimicking or truly representing the in vivo environment. This review focuses on long-acting drug delivery systems (LADDS), particularly implantable drug delivery systems (IDDS), their formulation, methods of characterization, and clinical application for the treatment of eye diseases.

The Autoimmune Rheumatic Disease Related Dry Eye and Its Association with Retinopathy

Dry eye disease is a chronic disease of the ocular surface characterized by abnormal tear film composition, tear film instability, and ocular surface inflammation, affecting 5% to 50% of the population worldwide. Autoimmune rheumatic diseases (ARDs) are systemic disorders with multi-organ involvement, including the eye, and play a significant role in dry eye. To date, most studies have focused on Sjögren's syndrome (one of the ARDs) since it manifests as two of the most common symptoms-dry eyes and a dry mouth-and attracts physicians to explore the relationship between dry eye and ARDs. Many patients complained of dry eye related symptoms before they were diagnosed with ARDs, and ocular surface malaise is a sensitive indicator of the severity of ARDs. In addition, ARD related dry eye is also associated with some retinal diseases directly or indirectly, which are described in this review. This review also summarizes the incidence, epidemiological characteristics, pathogenesis, and accompanying ocular lesions of ARD's related dry eye, emphasizing the potential role of dry eye in recognition and monitoring among ARDs patients.

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.

A Review of Applications and Intracellular Mechanisms of Intense Pulsed Light in Eyelid Inflammatory Diseases

Objective: To evaluate relevant clinical outcomes and conclude possible mechanisms of intense pulsed light (IPL) in eyelid inflammation. Background: IPL devices were primarily applied in cutaneous vascular malformations and have been used in ocular diseases for about 20 years, mostly including meibomian gland dysfunction (MGD), blepharitis, and ocular rosacea. Recent findings: Seventy-two original clinical researches were included, 57 for MGD, 4 for blepharitis or blepharitis-related keratoconjunctivitis, and 11 for rosacea. Dry eye symptoms, (tear) break-up time (BUT), and meibomian structure and/or functions were improved in most patients, but production of reactive oxygen species is an important link in the photobiomodulation mediated by IPL, which can influence numerous signal pathways to achieve anti-inflammatory, anti-infective, and prodifferentiation effects. Conclusions: The evidence suggests that IPL is an effective therapeutic tool for most patients with MGD, but more clinical evidence is needed for other indications.

Anti-Inflammatories in the Treatment of Dry Eye Disease: A Review

Inflammation is an important driver of dry eye disease (DED) pathogenesis. An initial insult that results in the loss of tear film homeostasis can initiate a nonspecific innate immune response that leads to a chronic and self-sustaining inflammation of the ocular surface, which results in classic symptoms of dry eye. This initial response is followed by a more prolonged adaptive immune response, which can perpetuate and aggravate inflammation and result in a vicious cycle of chronic inflammatory DED. Effective anti-inflammatory therapies can help patients exit this cycle, and effective diagnosis of inflammatory DED and selection of the most appropriate treatment are therefore key to successful DED management and treatment. This review explores the cellular and molecular mechanisms of the immune and inflammatory components of DED, and examines the evidence base for the use of currently available topical treatment options. These agents include topical steroid therapy, calcineurin inhibitors, T cell integrin antagonists, antibiotics, autologous serum/plasma therapy, and omega-3 fatty acid dietary supplements.

Meibomian Gland Dysfunction: A Route of Ocular Graft-Versus-Host Disease Progression That Drives a Vicious Cycle of Ocular Surface Inflammatory Damage

PURPOSE

To investigate the role of aggressive meibomian gland dysfunction (MGD) in the immune pathogenesis of ocular graft-vs-host disease (GVHD).

METHODS

In mice, an allogeneic GVHD model was established by transferring bone marrow (BM) and purified splenic T cells from C57BL/6J mice into irradiated C3-SW.H2b mice (BM+T). Control groups received BM only. Mice were scored clinically across the post-transplantation period. MGD severity was categorized using the degree of atrophy on harvested lids. Immune disease was analyzed using flow cytometry of tissues along with fluorescent tracking of BM cells onto the ocular surface. In humans, parameters from 57 patients with ocular GVHD presenting to the Duke Eye Center were retrospectively reviewed. MGD was categorized using the degree of atrophy on meibographs. Immune analysis was done using high-parameter flow cytometry on tear samples.

RESULTS

Compared with BM only, BM+T mice had higher systemic disease scores that correlated with tear fluid loss and eyelid edema. BM+T had higher immune cell infiltration in the ocular tissues and higher CD4+-cell cytokine expression in draining lymph nodes. BM+T mice with worse MGD scores had significantly worse corneal staining. In patients with ocular GVHD, 96% had other organs affected. Patients with ocular GVHD had abnormal parameters on dry eye testing, high matrix metalloproteinase-9 positivity (92%), and abundance of immune cells in tear samples. Ocular surface disease signs were worse in patients with higher MGD severity scores.

CONCLUSIONS

Ocular GVHD is driven by a systemic, T-cell-dependent process that causes meibomian gland damage and induces a robust form of ocular surface disease that correlates with MGD severity. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Recovery of Corneal Innervation after Treatment in Dry Eye Disease: A Confocal Microscopy Study

PURPOSE

To analyze the changes in corneal innervation by means of in vivo corneal confocal microscopy (IVCM) in patients diagnosed with Evaporative (EDE) and Aqueous Deficient Dry Eye (ADDE) and treated with a standard treatment for Dry Eye Disease (DED) in combination with Plasma Rich in Growth Factors (PRGF).

METHODS

Eighty-three patients diagnosed with DED were enrolled in this study and included in the EDE or ADDE subtype. The primary variables analyzed were the length, density and number of nerve branches, and the secondary variables were those related to the quantity and stability of the tear film and the subjective response of the patients measured with psychometric questionnaires.

RESULTS

The combined treatment therapy with PRGF outperforms the standard treatment therapy in terms of subbasal nerve plexus regeneration, significantly increasing length, number of branches and nerve density, as well as significantly improving the stability of the tear film (p < 0.05 for all of them), and the most significant changes were located in the ADDE subtype.

CONCLUSIONS

the corneal reinnervation process responds in a different way depending on the treatment prescribed and the subtype of dry eye disease. In vivo confocal microscopy is presented as a powerful technique in the diagnosis and management of neurosensory abnormalities in DED.

Management of Sjogren's Dry Eye Disease-Advances in Ocular Drug Delivery Offering a New Hope

Sjögren's syndrome is a chronic and insidious autoimmune disease characterized by lymphocyte infiltration of exocrine glands. Patients typically present with dry eye, dry mouth, and other systemic manifestations. Currently, the available molecules and drug-delivery systems for the treatment of Sjögren's syndrome dry eye (SSDE) have limited efficacy since they are not specific to SSDE but to dry eye disease (DED) in general. The current treatment modalities are based on a trial-and-error approach using primarily topical agents. However, this approach gives time for the vicious cycle of DED to develop which eventually causes permanent damage to the lacrimal functional unit. Thus, there is a need for more individualized, specific, and effective treatment modalities for SSDE. The purpose of this article is to describe the current conventional SSDE treatment modalities and to expose new advances in ocular drug delivery for treating SSDE. A literature review of the pre-clinical and clinical studies published between 2016 and 2022 was conducted. Our current understanding of SSDE pathophysiology combined with advances in ocular drug delivery and novel therapeutics will allow the translation of innovative molecular therapeutics from the bench to the bedside.

Developing advanced therapeutics through the study of naturally occurring immune-mediated ocular disease in domestic animals

This review, which is part of the "Currents in One Health" series, describes the importance of the study of immune-mediated ocular disease in the development of innovative therapeutics, such as cell and gene therapy for the eye. Recent examples of cell and gene therapy studies from the author's laboratory are reviewed to emphasize the importance of One Health initiatives in developing innovative therapies for ocular diseases. Spontaneous immune-mediated corneal disease is common in horses, cats, dogs, and humans. Autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) injected subconjunctivally resulted in the resolution of naturally occurring immune-mediated keratitis (IMMK) without adverse effects. These results support that autologous subconjunctival BM-MSC therapy may be a viable treatment alternative for IMMK. Furthermore, the use of subconjunctival MSCs may be an effective method to treat ocular surface immune-mediated diseases in humans and other species, including herpetic stromal keratitis and immunologic dry eye disease. Furthermore, the use of adeno-associated viral (AAV) vectors to deliver the immunosuppressive transgene cDNA of equine interleukin 10 (eqIL-10) or human leukocyte antigen G injected intravitreally was shown to be safe and inhibited the development of uveitis in the experimental autoimmune uveitis rat model. Efficacy and safety studies of ocular gene therapy in models will pave the way for clinical trials in animals with naturally occurring immune-mediated diseases, such as a therapeutic clinical trial for AAV-eqIL-10 in horses with equine recurrent uveitis.

How study of naturally occurring ocular disease in animals improves ocular health globally

In this article, which is part of the Currents in One Health series, the role of naturally occurring ocular disease in animals is reviewed with emphasis on how the understanding of these ocular diseases contributes to one health initiatives, particularly the pathogenesis and treatment of ocular diseases common to animals and humans. Animals spontaneously develop ocular diseases that closely mimic those in humans, especially dry eye disease, herpes virus infection (cats), fungal keratitis (horses), bacterial keratoconjunctivitis, uveitis, and glaucoma. Both uveitis and glaucoma are common in domestic animals and humans, and many similarities exist in pathogenesis, genetics, and response to therapy. Furthermore, the study of inherited retinal disease in animals has particularly epitomized the one health concept, specifically the collaborative efforts of multiple disciplines working to attain optimal health for people and animals. Through this study of retinal disease in dogs, innovative therapies such as gene therapy have been developed. A unique opportunity exists to study ocular disease in shared environments to better understand the interplay between the environment, genetics, and ocular disease in both animals and humans. The companion Currents in One Health by Gilger, AJVR, December 2022, addresses in more detail recent studies of noninfectious immune-mediated animal ocular disease and their role in advancing ocular health globally.

Aqueous Humour Ofloxacin Concentration after Topical Instillation in Patients with Dry Eye Disease

Background and Objectives: A prospective, randomized clinical trial was conducted to evaluate the concentration of ofloxacin in the aqueous humour (AqH) of patients suffering from dry eye disease (DED) after topical instillation. Materials and Methods: Ninety-one (91) cataract patients scheduled for phacoemulsification were categorized into three groups according to DED severity. Group I (n = 17) was comprised of subjects without DED, patients in group II (n = 37) were evaluated as having non-severe DED, while group III (n = 37) consisted of patients suffering from severe DED. Preoperatively, patients received 4 drops of 0.3% of ofloxacin at 15 min intervals. One hour after the last instillation, aqueous samples were collected intraoperatively. Results: The median AqH concentration of ofloxacin in group I was 199.9 ng/mL (range 92.2−442.8 ng/mL), while in group II it was 530.5 ng/mL (range 283.7−1004.9 ng/mL), and 719.2 ng/mL (range 358.0−1512.4 ng/mL) in Group III, p < 0.001 (Kruskal-Wallis tests). Pairwise tests (two-tailed with Bonferroni corrections) between groups resulted in a p-value of 0.001 when group II was compared to group I and group III was compared to group I, and a p-value of 0.020 when group II was compared to group III. The severity of DED, across groups I, II, and III, and the levels of ofloxacin revealed a strong positive correlation (r = 0.639, p < 0.001). Conclusions: Ofloxacin concentration in the AqH after topical drop instillation may be affected by the degree of ocular surface inflammation in patients suffering from DED.

Ocular Surface Immune Cell Profiles in Contact Lens-Induced Discomfort

Purpose

Contact lens–induced discomfort (CLD) remains a primary factor in discontinuation or prevention of contact lens wear. Thus, we investigated the role of ocular surface immune cells in subjects with CLD.

Methods

Habitual contact lens (CL) wearers with CLD (n = 19; 38 eyes) and without CLD (n = 21; 42 eyes) as determined by the Contact Lens Dry Eye Questionnaire-8 was included in a trial. Enrolled subjects used either of the two types of CL (designated as CL-A or CL-D). Ocular surface cells from the bulbar conjunctiva were obtained by impression cytology. The collected cells were phenotyped using fluorochrome-conjugated antibodies specific for leukocytes (CD45⁺), neutrophils (CD66b^+,High,Low), macrophages (CD163⁺), T cells (CD3⁺CD4⁺, CD3⁺CD8⁺), natural killer (NK) cells (CD56^{+, High, Low}), natural killer T (NKT) cells (CD3⁺CD56⁺), and gamma delta T (γδT) cells (CD3⁺γδTCR⁺) by flow cytometry. Further, corneal dendritic cell density (cDCD) was also determined using in vivo confocal microscopy.

Results

Significantly higher proportions of CD45⁺ cells were observed in subjects with CLD compared to those without CLD. The percentages of CD66b^Total,Low, CD163⁺, pan T cells, CD4⁺T cells, CD8⁺T cells, CD56^{Total,High,Low} (NK) cells, and NKT cells, as well as the CD4/CD8 ratio, were significantly higher in CLD subjects. The proportion of T cells (CD4, CD8, CD4/CD8 ratio, NKT cells) and macrophages exhibited a direct association with discomfort score. The percentages of CD45⁺, CD66b^Total,Low, CD163⁺, CD3⁺, CD56^{Total,High,Low}, and NKT cells and cDCD were significantly higher in CLD subjects wearing CL-D. The percentages of CD66b^High, CD4⁺T cells, CD8⁺T cells, NKT cells, and CD4/CD8 ratio were significantly higher in CLD subjects wearing CL-A.

Conclusions

Increased proportions of ocular surface immune cells are observed in CLD, and the lens type could impact the immune cells associated with CLD.

Translational Relevance

The association between the proportion of altered ocular surface immune cell subsets and contact lens–induced discomfort underpins the importance of considering immune-related aspects during contact lens development and in the clinical management of ocular surface pain.

Autophagy Protects Ocular Surface Against Overactivated Inflammation by Degrading Retinoic Acid-Induced Gene-I in Human Conjunctival Epithelial Cells

Purpose: To evaluate the pathological role of autophagy in dry eye diseases by detecting the autophagic degradation of RIG-I, a master RNA-sensing receptor in cells. Methods: RNA-sequencing analysis and qPCR analysis of the expression level of genes related to IFN-I signaling pathway was used to evaluate the inflammatory level of cells overexpressed with RIG-I or empty vector, which was further confirmed by WB analysis. Chemical treatment (3-methyladenine, chloroquine, NH₄Cl, rapamycin, torin 1 or trehalose) or gene knockdown was used to modulate autophagy. When the autophagy level was regulated, the autophagic degradation of RIG-I and its pathological role in dry eye diseases were determined by detecting the protein level of RIG-I and the level of cell inflammation. Results: Cells that overexpressed RIG-I showed increased expression of genes involved in the IFN-I signaling pathway compared with cells transfected with an empty vector. Inhibition of autophagy leaded to the accumulation of RIG-I in HCECs, combined with the aggravation of the RIG-I-mediated IFN-I signaling pathway. Contrarily, promoting the autophagic degradation of RIG-I by trehalose treatment could alleviate IFN-I signaling pathway. Conclusions: Autophagy could protect the ocular surface against IFN-I signaling pathway by degrading RIG-I in HCECs. This process may restrict the overactivation of inflammation in the pathological development of dry eye disease.

Lacrimal Gland Insufficiency in Aqueous Deficiency Dry Eye Disease: Recent Advances in Pathogenesis, Diagnosis, and Treatment

BACKGROUND

Aqueous deficiency dry eye disease is a chronic and potentially sight-threatening condition, that occurs due to the dysfunction of the lacrimal glands. The aim of this review was to describe the various recent developments in the understanding, diagnosis and treatment of lacrimal gland insufficiency in aqueous deficiency dry eye disease.

METHODS

A MEDLINE database search using PubMed was performed using the keywords: "dry eye disease/syndrome", "aqueous deficient/deficiency dry eye disease", "lacrimal gland" and "Sjogren's syndrome". After scanning through 750 relevant abstracts, 73 eligible articles published in the English language from 2016 to 2021 were included in the review.

RESULTS

Histopathological and ultrastructural studies have revealed new insights into the pathogenesis of cicatrising conjunctivitis-induced aqueous deficiency, where the lacrimal gland acini remain uninvolved and retain their secretory property, while significant ultrastructural changes in the gland have been observed. Recent advances in diagnosis include the techniques of direct clinical assessment of the lacrimal gland morphology and secretion, tear film osmolarity, tear film lysozyme and lactoferrin levels, tear film interferometry and lacrimal gland confocal microscopy. Developments in the treatment of aqueous deficiency dry eye disease, apart from the nanoparticle-based tear substitutes, include secretagogues like diquafosol tetrasodium and rebamipide, anti-inflammatory topical agents like nanomicellar form of cyclosporine and lifitegrast, scleral contact lenses, neurostimulation, and acupuncture for increasing the amount of tear production, minor salivary gland transplantation, faecal microbial transplantation, lacrimal gland regeneration and mesenchymal stem cell therapy.

CONCLUSIONS

Significant advances in the understanding, diagnosis and management of lacrimal gland insufficiency and its role in aqueous deficiency dry eye disease have taken place within the second half of the last decade. Of which, translational breakthroughs in terms of newer drug formulations and regenerative medicine are most promising.

Dry Eye and Meibomian Gland Dysfunction in Neovascular Age-Related Macular Degeneration Patients Treated with Intravitreal Injections

Objectives:

To determine if patients treated with multiple intravitreal injections for neovascular age-related macular degeneration are more likely to suffer from dry eye and meibomian gland dysfunction.

Materials and Methods:

Sixty eyes of 30 patients were enrolled. One eye of each patient was treated with multiple monthly intravitreal injections for neovascular AMD (Group 1) and the fellow healthy eye received no treatment (Group 2). The presence of dry eye was evaluated using tear film break-up time, Schirmer 1 test, the Oxford scale, and Ocular Surface Disease Index (OSDI). The loss rate of meibomian glands was evaluated by meibography and was graded and scored (meiboscore) from grade 0 (no loss of glands) to grade 3 (loss of >2/3 of total meibomian glands) for each eyelid.

Results:

Group 1 had lower mean Schirmer 1 and tear film break up-time measurements and higher mean OSDI score than Group 2, but the differences were not statistically significant (p=0.257, p=0.113, and p=0.212, respectively). Mean Oxford scale scores and meiboscore of the upper eyelids showed no statistically significant difference between the groups (p=0.594, p=0.663, respectively). The meiboscore of the lower eyelids was significantly higher in Group 1 (p=0.048).

Conclusion:

Multiple factors such as povidone-iodine and the preservatives in topical eye drops may cause inflammation leading to ocular surface damage in patients treated with multiple intravitreal injections. As the treatment requires repeated injections, exposure to these factors might worsen the ocular surface inflammation. The possibility of dry eye and meibomian gland dysfunction should be considered in these patients.

Molecular Characteristics and Distribution of Adult Human Corneal Immune Cell Types

Background

The limbus is located at a 2-mm-wide area between the bulbar conjunctiva and the cornea and has been suggested to be the niche of corneal epithelial stem cells and immune cells. Like the skin and intestines, the cornea is also an important mucosal surface, and immune cells on the cornea play critical roles in immune surveillance to ensure barrier surface homeostasis and protection from various environmental damage and infections. Single-cell RNA sequencing (scRNA-seq) analysis of protein tyrosine phosphatase receptor type C positive (PTPRC⁺) hematopoietic cells from the corneal limbus could provide a single cell atlas of all the immune cell subsets.

Methods

We performed single-cell RNA sequencing to generate transcriptomic profile for 804 sort-purified hematopoietic cells from the corneal limbus of three healthy donors.

Results

Our analysis identified a primary transcriptomic pattern for multiple immune cell subtypes, including naive T cells, antiviral effector CD8⁺ T cells, and innate immune cells such as IDO1⁺ mature regulatory dendritic cells (mregDCs), macrophages, monocytes, and basophils in the human corneal limbus.

Conclusion

Overall, single-cell transcriptomic analysis of limbal immune cells suggested the possible contribution of these cells on the adaptive and innate immune response of the human cornea.

Comparison of treatment effects between 4.9% N-acetyl-aspartyl glutamic acid and 0.05% cyclosporine A eye drops in dry eye patients

PURPOSE

We aimed to investigate the difference in the treatment effects of 4.9% N-acetyl-aspartyl glutamic acid (NAAGA) and 0.05% cyclosporine A (CsA) eye drops in dry eye patients.

METHODS

We retrospectively reviewed the medical records of 86 patients (86 eyes) who were diagnosed with dry eye and treated with NAAGA or CsA eye drops. Patients treated with NAAGA or CsA eye drops were designated as group A or B, respectively. We also calculated Ocular Surface Disease Index (OSDI), dry eye, and meibomian gland dysfunction (MGD) parameters before treatment and at 1 and 3 months after treatment. Eye drop discomfort was assessed by calculating visual analog scale (VAS) scores at 1 month and 3 months after treatment.

RESULTS

There were no significant differences in patients' demographics and OSDI, dry eye, and MGD parameters between the two groups. OSDI, dry eye, and MGD parameters at 1 month and 3 months after treatment were found to be improved in both groups. However, at 1 month after treatment, the dry eye and MGD parameters of group A, except for corneal fluorescein staining, showed more improvement than those of group B. Additionally, at 3 months after treatment, the lid margin abnormality score, corneal staining score, tear break-up time, and OSDI of group A were significantly lower than those of group B. VAS scores of group A at 1 and 3 months after treatment were significantly lower than those of group B.

CONCLUSION

Treatment with NAAGA eye drops was effective in dry eye patients and demonstrated faster treatment response and less discomfort during application than CsA eye drops.

Comparison Between Heated Eye Mask and Intense Pulsed Light Treatment for Contact Lens-Related Dry Eye

Background: Contact lens-related dry eye (CLDE) is common in contact lens (CL) wearers and can lead to ocular pain, decreased visual quality, and reduced quality of life. Objective: The purpose of this prospective, randomized, examiner masked study was to compare the effectiveness of intense pulsed light (IPL) and heated eye mask (HEM) for relieving CLDE. Methods: The final analysis included 60 patients (30 in the IPL group and 30 in the HEM group) who were using CL and had been suffering contact lens discomfort for more than a year. The IPL treatment group had two IPL treatments spaced 3 weeks apart, whereas the HEM group received HEM daily for 6 weeks (42 days). Non-invasive tear break-up time (NITBUT), tear-film lipid layer (TFLL), conjunctival fluorescein staining, meibum gland quality and expression, conjunctival redness score, ocular surface disease index (OSDI), best-corrected visual acuity, endothelial cell count, and intraocular pressure were assessed at baseline: first visit (V1), second visit (V2), and third visit (V3). Results: The mean age of the IPL group was 28.6 ± 4.3 years (16 females, 53%) and that of the HEM group was 28.6 ± 4.2 years (16 females, 53%). Mean NITBUT for the IPL group at V2 was 5.53 ± 0.77 sec (p < 0.001) and at V3 was 7.72 ± 0.88 sec (p < 0.001); the IPL group demonstrated a clinically and statistically significant improvement in mean NITBUT. In addition, the HEM group showed a clinically and statistically significant improvement in mean NITBUT at V3 (5.86 ± 0.76 sec, p < 0.001). At V3, the C-OSDI, TFLL score, and meibum gland quality and expressibility all increased considerably (p < 0.05) in both groups. Conclusions: Our results imply that IPL or HEM treatment of CLDE can be safely used to relieve symptoms of CLDE. In addition, IPL treatment is more effective in improving the general stability of the tear-film and decreasing the need for artificial tears in CLDE.

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.

Once-Daily Topical Phosphosulindac Is Efficacious in the Treatment of Dry Eye Disease: Studies in Rabbit Models of Its Main Clinical Subtypes

Purpose: Dry eye disease (DED) is classified as aqueous deficient, evaporative, or mixed. We investigated the therapeutic effect of the novel anti-inflammatory drug phosphosulindac (PS) in rabbit models of DED encompassing its pathogenesis, and its transition to chronicity.

Methods: We treated three rabbit models of DED with PS (hydrogel formulation) or vehicle topically applied 1 × /day. We induced aqueous-deficient DED (acute and chronic) by injecting Concanavalin A into lacrimal glands; evaporative DED by injecting into the upper eyelid inactivated Mycobacterium tuberculosis in complete Freund's adjuvant; and mixed DED through desiccative stress, induced by holding open the eye for 3 h. We determined corneal sensitivity, tear break-up time (TBUT), Schirmer's tear test (STT), tear osmolality, and fluorescein staining of the ocular surface.

Results: PS reversed all abnormal DED parameters. In acute DED, PS dose dependently normalized corneal sensitivity and tear osmolality; and improved TBUT, STT, and fluorescein staining. PS normalized corneal sensitivity and improved all other parameters in chronic aqueous-deficient DED. In evaporative DED, PS normalized corneal sensitivity and improved TBUT and fluorescein staining (osmolality and STT were not significantly changed in this model). In the desiccative stress model, PS improved TBUT and fluorescein staining but had no effect on STT or tear osmolality.

Conclusions: PS rapidly reversed almost all DED parameters in its three subtypes. The normalization of the suppressed corneal sensitivity suggests the possibility of marked symptomatic relief by PS. The hydrogel formulation allows once-daily dosing. PS merits further development as a potential treatment for DED.

Corneal lymphangiogenesis as a potential target in dry eye disease - a systematic review

Dry eye disease (DED) is a common ocular surface condition causing symptoms of significant discomfort, visual disturbance, and pain. With recent advancements, DED has become recognized as a chronic self-perpetuating inflammatory condition triggered by various internal and environmental factors. DED has been shown to arise from the activation of both the innate and adaptive immune systems, leading to corneal epithelium and lacrimal gland dysfunction. While the cornea is normally avascular and thus imbued with angiogenic and lymphangiogenic privilege, various DED models have revealed activated corneal antigen-presenting cells in regional lymph nodes, suggesting the formation of new corneal lymphatic vessels in DED. The recent availability of reliable lymphatic cell surface markers such as LYVE-1 has made it possible to study lymphangiogenesis. Accordingly, numerous studies have been published within the last decade discussing the role of lymphangiogenesis in DED pathology. We systematically review the literature to identify and evaluate studies presenting data on corneal lymphangiogenesis in DED. There is considerable evidence supporting corneal lymphangiogenesis as a central mediator of DED pathogenesis. These findings suggest that anti-lymphangiogenic therapeutic strategies may be a viable option for the treatment of DED, a conclusion supported by the limited number of reported clinical trials examining anti-lymphangiogenic modalities in DED.

Attrition und Osmokinetik – Zwei Konzepte zur Pathogenese des Trockenen Auges

Die neuen Erkenntnisse der Pathophysiolgie des Trockenen Auges erkennen das Zusammenspiel von Tränen, Augenoberfläche und Lidoberfläche als eine funktionelle Einheit an. Der Begriff der Benetzungsfähigkeit der Tränen in Abhängigkeit der mikrotektonischen Anatomie der Augenoberfläche relativiert die Anforderungen an Träne und Tränenersatzmittel. Das Model der Attrition, welches die Effekte der friktionsneutralisierenden Kapazität des Tränenfilms, der Reibung und die Bedeutung der Mechanotransduktionskapazität des Epithels zusammenfasst, wird eingeführt und dessen pathophysiologische Bedeutung erläutert. Attrition und Benetzung bestimmen zusammen grundlegende pathophysiologische Vorgänge in der Augenoberfläche wie Aktivierung von Nerven (subjektive Beschwerden) sowie Entzündung und beeinflussen damit die Dynamik der Pathophysiologie, und den Übergang von vorübergehenden Beschwerden zu einer manifesten Erkrankung des Trockenen Auges. Die Betrachtung der Osmolarität als numerischer statischer Grenzwert zur alleinigen Diagnose des Trockenen Auges ist klinisch nicht haltbar. Das neue, dynamische Model der Osmokinetik, zeigt dagegen eine Alternative auf, in der die Tageschwankungen und die Beachtung des durchschnittlichen Osmolaritätsniveaus gröβere Bedeutung gewinnen und damit der eigentlichen pathophysiologischen Bedeutung der Osmolarität gerechter wird.

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

Dry eye disease is a common and frequently occurring ophthalmology with complex and diverse causes, and its incidence is on the upward trend. The pathogenesis of DED is still completely clear. However, the immune response based on inflammation has been recognized as the core basis of this disease. In this review, we will systematically review the previous research on the treatment of DED in immune inflammation, analyze the latest views and research hotspots, and provide reference for the prevention and treatment of DED.

Differential Effect of Proinflammatory Cytokines on Corneal and Conjunctival Epithelial Cell Mucins and Glycocalyx

Purpose

Ocular surface mucins and glycocalyx are critical for providing ocular hydration as well lubrication and repelling pathogens or allergens. Elevated levels of tear proinflammatory cytokines in dry eye may have detrimental effect on mucins and glycocalyx. The present study tested the effect of proinflammatory cytokines IL-6, TNF-α, and IFN-γ on membrane-tethered mucins expression, glycocalyx, and viability of ocular surface epithelial cells.

Methods

Stratified cultures of human corneal and conjunctival epithelial cells were exposed to different concentrations of IL-6, TNF-α, and IFN-γ for 24 hours. The mucins gene and protein expressions were quantified by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). The glycocalyx was imaged using confocal microscopy after staining with Alexa 488-conjugated wheat germ agglutinin lectin. Apoptotic and necrotic cell death was quantified using flow cytometry.

Results

IL-6, TNF-α, and IFN-γ treatment resulted in a significant increase in mucins (MUC)1 and MUC4 gene and protein expression in human corneal epithelial cells but caused no significant changes in the levels of these mucins in conjunctival epithelial cells. Further, these cytokines decreased MUC16 expression in both corneal and conjunctival epithelial cells. Moreover, no notable change in glycocalyx or apoptotic cell death in corneal and conjunctival epithelial cells was noted with any of the tested cytokines, but IL-6 and TNF-α exposure increased necrotic cell death in corneal and conjunctival epithelial cells, respectively.

Conclusions

Our results demonstrate that proinflammatory cytokines have differential effects on human corneal and conjunctival epithelial cell mucins expression, but do not cause any damage to ocular surface epithelial cell glycocalyx.

Proteoglycan 4 (PRG4) expression and function in dry eye associated inflammation

Dry eye disease (DED) affects hundreds of millions of people worldwide. It is characterized by the production of inflammatory cytokines and chemokines as well as damaging matrix metalloproteinases (MMPs) at the ocular surface. While proteoglycan 4 (PRG4), a mucin-like glycoprotein present at the ocular surface, is most well known as a boundary lubricant that contributes to ocular surface integrity, it has been shown to blunt inflammation in various cell types, suggesting a dual mechanism of action. Recently, full-length recombinant human PRG4 (rhPRG4) has been shown to improve signs and symptoms of DED in humans. However, there remains a significant need for basic science research on rhPRG4's biological properties and its potential therapeutic mechanisms of action in treating DED. Therefore, the objectives of this study were to characterize endogenous PRG4 expression by telomerase-immortalized human corneal epithelial (hTCEpi) cells, examine whether exogenous rhPRG4 modulates cytokine and chemokine secretion in response to dry eye associated inflammation (TNFα and IL-1β), explore interactions between rhPRG4 and MMP-9, and understand how experimental dry eye (EDE) in mice affects PRG4 expression. PRG4 secretion from hTCEpi cells was quantified by Western blot and expression visualized by immunocytochemistry. Cytokine/chemokine production was measured by ELISA and Luminex, while rhPRG4's effect on MMP-9 activity, binding, and expression was quantified using an MMP-9 inhibitor kit, surface plasmon resonance, and reverse transcription polymerase chain reaction (RT-PCR), respectively. Finally, EDE was induced in mice, and PRG4 was visualized by immunohistochemistry in the cornea and by Western blot in lacrimal gland lysate. In vitro results demonstrate that hTCEpi cells synthesize and secrete PRG4, and PRG4 secretion is inhibited by TNFα and IL-1β. In response to these pro-inflammatory stresses, exogenous rhPRG4 significantly reduced the stimulated production of IP-10, RANTES, ENA-78, GROα, MIP-3α, and MIG, and trended towards a reduction of MIP-1α and MIP-1β. The hTCEpi cells were also able to internalize fluorescently-labelled rhPRG4, consistent with a mechanism of action that includes downstream biological signaling pathways. rhPRG4 was not digested by MMP-9, and it did not modulate MMP-9 gene expression in hTCEpi cells, but it was able to bind to MMP-9 and inhibited in vitro activity of exogenous MMP-9 in the presence of human tears. Finally, in vivo results demonstrate that EDE significantly decreased immunolocalization of PRG4 on the corneal epithelium and trended towards a reduction of PRG4 in lacrimal gland lysate. Collectively these results demonstrate rhPRG4 has anti-inflammatory properties on corneal epithelial cells, particularly as it relates to mitigating chemokine production, and is an inhibitor of MMP-9 activity, as well as that in vivo expression of PRG4 can be altered in preclinical models of DED. In conclusion, these findings contribute to our understanding of PRG4's immunomodulatory properties in the context of DED inflammation and provide the foundation and motivation for further mechanistic research of PRG4's properties on the ocular surface as well as expanding clinical evaluation of its ability as a multifunctional therapeutic agent to effectively provide relief to those who suffer from DED.

Altered ocular surface immune cell profile in patients with dry eye disease

PURPOSE

Aberrant inflammation and immune dysregulation are known pathogenic contributors in dry eye disease (DED). Aim of the study was to determine the proportions of immune cell subsets on the ocular surface (OS) of DED patients.

METHODS

15 healthy controls (22 eyes) and 48 DED subjects (36 eyes with evaporative DED - EDED; 60 eyes with aqueous deficient DED - ADED) were included in the study. Tear break up time (TBUT), Schirmer's test 1 (ST1), corneal staining (CS) and ocular surface disease index (OSDI) scoring were recorded. OS wash was used to collect immune cells on the OS of study subjects. The cells immunophenotyped using flow cytometry include leukocytes, neutrophils, macrophages, natural killer-NK cells and T cell subsets (CD4; CD8; double positive-DP; gamma delta-γδ and NK T cells).

RESULTS

Significantly higher proportions of leukocytes, neutrophils, CD4 T cells, CD8 T cells, DP T cells and CD4/CD8 T cells ratio were observed in EDED and/or ADED patients. Significantly higher proportions of neutrophils and lower proportions of NK cells were observed in ADED subjects with corneal staining compared to those without and controls. Neutrophils/NK cells ratio was significantly higher in EDED and ADED subjects compared to controls. Correlation analysis revealed pathological relationships between proportions of leukocytes, neutrophils, CD4 T cells and Neutrophil/NK cells ratio with DED clinical parameters.

CONCLUSION

OS immune cell subset proportion changes in DED patients were associated with DED types and severity. The data suggests the potential for a new generation of therapies targeting immune cells on the ocular surface.

Corneal collagen as a potential therapeutic target in dry eye disease

Dry eye disease (DED) is a major cause of ocular discomfort, inflammation and dysfunction worldwide. Tear film instability in DED both causes and is exacerbated by disruption of the corneal epithelium. This tandem leads to a cycle of inflammation at the corneal surface involving immune cell dysregulation and increased chemokines and cytokines, which activate mitogen-activated protein kinases in the epithelium and elevates matrix metalloproteinases (MMPs). We review evidence suggesting that corneal collagen might be highly susceptible in DED to MMP-induced disruption, digestion, and thinning. We also summarize that collagen is far from inert and contains binding sites that serve as ligands for multiple inflammatory and immune regulators. Fragmented collagen not only challenges these receptor-ligand binding relationships, but also can promote recruitment and motility of pro-inflammatory immune cells. Current physician-directed therapies for DED focus on reducing inflammation, but do not directly ameliorate the underlying corneal damage that could exacerbate surface inflammation. We argue that an important gap in practice is lack of a direct therapeutic reparative for damaged corneal collagen, which is slow to heal, and likely amplifies sight-threatening inflammation. Healing fragmented collagen in the cornea may represent a more effective means to interrupt the "vicious cycle" of inflammation in DED and other conditions that damages, sometimes irreversibly, the ocular surface.

Dry eye and Meibomian gland dysfunction evaluation in sarcoidosis patients

PURPOSE

To analyze the relation between Meibomian gland dysfunction, dry eye, and sarcoidosis.

MATERIALS AND METHODS

Twenty eyes of 10 sarcoidosis patients (Group 1) and 20 left eyes of 20 age-sex matched healthy volunteers (Group 2) were included. Presence of dry eye was evaluated with Schirmer 1 test, tear film break-up time (T-BUT), Oxford scale scoring, Ocular Surface Disease Index (OSDI) score assessments. A slit-lamp biomicroscope infrared filter (Topcon, SL-D701, IJssel, The Netherlands) was used to evaluate Meibomian glands. The drop-out ratio according to meibography was scored for each eyelid from grade 0 (no loss) through grade 3 (lost area >2/3 of the total Meibomian gland area).

RESULTS

Among dry eye tests mean Schirmer 1 and T-BUT values were lower and OSDI score was higher in Group 1 compared to Group 2 and the differences were statistically significant (p = 0.017, p = 0.039, p = 0.003, respectively). In addition, the upper, lower and total meiboscores were statistically significantly higher in Group 1 (p = 0.047, p = 0.003, p = 0.005, respectively).

CONCLUSION

A significantly higher presence of dry eye and Meibomian gland drop out ratios was detected in sarcoidosis patients. It is important to monitor sarcoidosis patients for dry eye and Meibomian gland dysfunction and when detected, to treat adequately to prevent ocular surface damage.

The cornea IV immunology, infection, neovascularization, and surgery chapter 1: Corneal immunology

PURPOSE

of Review: This review offers an informed and up-to-date insight on the immune profile of the cornea and the factors that govern the regulation of such a unique immune environment.

SUMMARY

The cornea is a unique tissue that performs the specialized task of allowing light to penetrate for visual interpretation. To accomplish this, the ocular surface requires a distinct immune environment that is achieved through unique structural, cellular and molecular factors. Not only must the cornea be able to fend off invasive infectious agents but also control the inflammatory response as to avoid collateral, and potentially blinding damage; particularly of post-mitotic cells such as the corneal endothelium. To combat infections, both innate and adaptive arms of the inflammatory immune response are at play in the cornea. Dendritic cells play a critical role in coordinating both these responses in order to fend off infections. On the other side of the spectrum, the ocular surface is also endowed with a variety of anatomic and physiologic components that aid in regulating the immune response to prevent excessive, potentially damaging, inflammation. This attenuation of the immune response is termed immune privilege. The balance between pro and anti-inflammatory reactions is key for preservation of the functional integrity of the cornea.

RECENT FINDINGS

The understanding of the molecular and cellular factors governing corneal immunology and its response to antigens is a growing field. Dendritic cells in the normal cornea play a crucial role in combating infections and coordinating the inflammatory arms of the immune response, particularly through coordination with T-helper cells. The role of neuropeptides is recently becoming more highlighted with different factors working on both sides of the inflammatory balance.

Experimental Pharmacotherapy for Dry Eye Disease: A Review

Dry eye disease (DED) is a complex multifactorial disease showing heterogenous symptoms, including dryness, photophobia, ocular discomfort, irritation and burning but also pain. These symptoms can affect visual function leading to restrictions in daily life activities and reduction in work productivity with a consequently high impact on quality of life. Several pathological mechanisms contribute to the disease: evaporative water loss leads to impairment and loss of tear homeostasis inducing either directly or indirectly to inflammation, in a self-perpetuating vicious cycle. Dysregulated ocular immune responses result in ocular surface damage, which further contributes to DED pathogenesis. Currently, DED treatment is based on a flexible stepwise approach to identify the most beneficial intervention. Although most of the available treatments may control to a certain extent some signs and symptoms of DED, they show significant limitations and do not completely address the needs of patients suffering from DED. This review provides an overview of the emerging experimental therapies for DED. Several promising therapeutic strategies are under development with the aim of dampening inflammation and restoring the homeostasis of the ocular surface microenvironment. Results from early phase clinical trials, testing the effects of EnaC blockers, TRPM8 agonist or mesenchymal stem cells in DED patients, are especially awaited to demonstrate their therapeutic value for the treatment of DED. Moreover, the most advanced experimental strategies in the pipeline for DED, tivanisiran, IL-1R antagonist EBI-005 and SkQ1, are being tested in Phase III clinical trials, still ongoing. Nevertheless, although promising results, further studies are still needed to confirm efficacy and safety of the new emerging therapies for DED.

A Review of the Mechanism of Action of Cyclosporine A: The Role of Cyclosporine A in Dry Eye Disease and Recent Formulation Developments

Dry eye disease (DED) is a multifactorial disease of the ocular surface and tear film that has gained awareness as a public health problem. Characteristics of DED include tear film instability, hyperosmolarity, and ocular surface inflammation, which can occur independently or may be a sequela of numerous ocular diseases, ocular surgery or contact lens wear. Much has been learned about the impact of the disease to help affected individuals who report symptoms of poor vision, pain, and tearing. Recently, new research highlights the importance of the role of ocular surface inflammation and damage in DED-leading to a vicious cycle of inflammation as well as loss of tear film homeostasis. DED immunopathophysiology is characterized by four stages: initiation, amplification, recruitment, and re-initiation. Cyclosporine is proven to be a valuable ophthalmic therapeutic for DED through its immunomodulatory actions and regulation of the adaptive immune response. Cyclosporine mechanism of action is well described in the published literature and the myriad of benefits in all four stages lend a broad-based immunomodulatory function particularly suitable for addressing DED. Furthermore, cyclosporine has unique goblet cell density improvement capabilities as well as anti-apoptotic properties. Topical formulations of cyclosporine are centered around addressing the highly lipophilic nature of the molecule. The poor aqueous solubility of cyclosporine traditionally presented technical challenges in drug delivery to the ocular surface. Newer formulations such as cationic emulsions and nanomicellar aqueous solutions address formulation, tissue concentration, and drug delivery challenges.

Genistein-Calcitriol Mitigates Hyperosmotic Stress-Induced TonEBP, CFTR Dysfunction, VDR Degradation and Inflammation in Dry Eye Disease

Dry eye disease (DED) signs and symptoms are causally associated with increased ocular surface (OS) inflammation. Modulation of key regulators of aberrant OS inflammation is of interest for clinical management. We investigated the status and the potential to harness key endogenous protective factors, such as cystic fibrosis transmembrane conductance regulator (CFTR) and vitamin D receptor (VDR) in hyperosmotic stress‐associated inflammation in patients with DED and in vitro. Conjunctival impression cytology samples from control subjects (n = 11) and patients with DED (n = 15) were used to determine the status of hyperosmotic stress (TonEBP/NFAT5), inflammation (IL‐6, IL‐8, IL‐17A/F, TNFα, MMP9, and MCP1), VDR, and intracellular chloride ion (GLRX5) by quantitative polymerase chain reaction and/or immunofluorescence. Human corneal epithelial cells (HCECs) were used to study the effect of CFTR activator (genistein) and vitamin D (calcitriol) in hyperosmotic stress (HOs)‐induced response in vitro. Western blotting was used to determine the expression of these proteins, along with p‐p38. Significantly, higher expression of inflammatory factors, TonEBP, GLRX5, and reduced VDR were observed in patients with DED and in HOs‐induced HCECs in vitro. Expression of TonEBP positively correlated with expression of inflammatory genes in DED. Increased TonEBP and GLRX5 provides confirmation of osmotic stress and chloride ion imbalance in OS epithelium in DED. These along with reduced VDR suggests dysregulated OS homeostasis in DED. Combination of genistein and calcitriol reduced HOs‐induced TonEBP, inflammatory gene expression, and p‐p38, and abated VDR degradation in HCECs. Henceforth, this combination should be further explored for its relevance in the management of DED.

Dry Eye in Systemic Sclerosis Patients: Novel Methods to Monitor Disease Activity

Background: In systemic sclerosis (SSc) patients, dry eye syndrome (DES) is the most frequent ocular feature. The aim of this study was to investigate ocular DES-related SSc patients and to establish any correlation with the severity of the disease. Methods: Retrospectively, data from 60 patients with SSc underwent ophthalmic examination, where non-invasive film tear break-up time (NIF-TBUT), tear film lipid layer thickness (LLT), anesthetic-free Schirmer test I, tear osmolarity measurement (TearLab System), and modified Rodnan skin score (mRSS) data were collected. The visual analog scale (VAS) and Symptom Assessment in Dry Eye (SANDE) methods were utilized. The results were correlated with mRSS and the duration of SSc. Results: Severe DES occurred in 84% of cases, and was more severe in women. The eyelids were involved in 86.6%, secondary to meibomian gland disease (MGD). A direct correlation was found between the tear osmolarity (mean 328.51 ± 23.8 SD) and skin score (mRSS) (r = 0.79; p < 0.01). Significantly reduced NIF-TBUT, LLT, and Schirmer test I values were observed in the case of severe skin involvement. Conclusions: SSc patients show lipid tear dysfunction related to the severity and duration of the disease due to inflammation and the subsequent atrophy of the meibomian glands.