Inflammation In Dry Eye Disease Research Articles

HIF1α-mediated TRAIL Expression Regulates Lacrimal Gland Inflammation in Dry Eye Disease.

PurposeThe purpose of this study was to investigate the expression of death ligands in the lacrimal glands (LGs), identify upstream factors that regulate their expression, and determine the functional roles of these factors in the pathogenesis of dry eye disease (DED).MethodsFor DED experiment, ex vivo coculture system with LG and in vivo murine model using a controlled environment chamber were utilized. C57BL/6 mice and hypoxia-inducible factor (HIF)-1α conditional knockout (CKO) mice were used. Immunohistochemical staining, polymerase chain reaction, and immunoblotting were performed to determine levels of death ligands including tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in DED-induced LGs. Additionally, acinar cell and CD45+ cell apoptosis was determined with neutralizing TRAIL treatment.ResultsDesiccating stress significantly increased HIF-1α expression in LG-acinar cells. Furthermore, HIF-1α deficiency significantly enhanced the infiltration of CD45+ inflammatory cells in LG and induced LG-acinar cell death. Meanwhile, only TRAIL expression was increased in DED-LG, but abrogated in HIF-1α CKO. Interestingly, the main source of TRAIL was the CD45– LG-acinar cells, but not CD45+ immune cells after DED induction. Using ex vivo coculture system, we confirmed LG-induced apoptosis of immune cells via HIF-1α-mediated TRAIL secretion following DED. Consistent with ex vivo, the insufficiency of HIF-1α and TRAIL enhanced recruitment of inflammatory cells to the LG and subsequently exacerbated ocular surface damage in DED mice.ConclusionsOur findings offer novel insight into the regulatory function of acinar cell-derived TRAIL in limiting inflammatory damage and could be implicated in the development of potential therapeutic strategies for DED.

Innate and Adaptive Cell Populations Driving Inflammation in Dry Eye Disease

Dry eye disease (DED) is the most common ocular disease and affects millions of individuals worldwide. DED encompasses a heterogeneous group of diseases that can be generally divided into two forms including aqueous-deficient and evaporative DED. Evidence suggests that these conditions arise from either failure of lacrimal gland secretion or low tear film quality. In its secondary form, DED is often associated with autoimmune diseases such as Sjögren's syndrome and rheumatoid arthritis. Current treatment strategies for DED are limited to anti-inflammatory medications that target the immune system as the source of deleterious inflammation and tissue injury. However, there is a lack of understanding of the underlying pathogenesis of DED, and subsequently, there are very few effective treatment strategies. The gap in our knowledge of the etiology of primary DED is in part because the majority of research in DED focused on secondary autoimmune causes. This review focuses on what is currently understood about the contribution of innate and adaptive immune cell populations in the pathogenesis of DED and highlights the need to continue investigating the central role of immunity driving DED.

Controlled release of an HDAC inhibitor for reduction of inflammation in dry eye disease

Dry eye disease (DED), also known as keratoconjunctivitis sicca, is an ocular surface disease characterized by T-cell-mediated inflammation. Current therapeutics, such as immunosuppressive agents, act to suppress the clinical signs and inflammation. However, long-term usage of these treatments can cause severe side effects. In this study, we present an alternative therapeutic approach that utilizes a histone deacetylase inhibitor (HDACi) to regulate transcription of a variety of immunomodulatory genes. Specifically, HDACi have emerged as a potential anti-inflammatory agent, which can modulate the functions of a subset of suppressive T lymphocytes known as regulatory T cells (Tregs), enhancing FoxP3 acetylation and subsequently guarding the transcription factor from proteasomal degradation. Here, a specific HDACi known as SAHA (suberoylanilide hydroxamic acid) was formulated to controllably release in the lacrimal gland. Intralacrimal gland injection of PLGA-based SAHA microspheres prevented clinical signs of DED in mice with Concanavalin A-induced DED, reduced expression of pro-inflammatory cytokines, and increased expression of FoxP3 in the lacrimal glands. Murine T cell culture experiments also revealed that SAHA decreased effector T cell proliferation and enhanced suppressive function of Tregs in co-cultures of Tregs and effector T cells. Statement of SignificanceIn this study, we demonstrate a therapeutic approach that utilizes a histone deactylase inhibitor (HDACi) to regulate transcription of a variety of immunomodulatory genes. HDACi have emerged as a potential anti-inflammatory agent, which can modulate the functions of a subset of suppressive T lymphocytes known as regulatory T cells (Tregs). Here, HDACi microspheres composed of a biocompatible and biodegradable polymer (poly(lactic-co-glycolic acid) (PLGA)), were able to locally release the HDACi and prevent clinical signs of DED. This work is timely given the recent shift in treatments of DED towards immunological based therapies to reduce ocular inflammation. However, notably, many of these treatments require large amounts of drug, and non-specifically suppress the immune system, leading to several systemic side effects. Instead of merely suppressing or blocking inflammation, the formulation described herein intends to balance the microenvironment promoting immunological homeostasis. This particular drug delivery system may also have broad implications in the field of inflammatory mediated ocular disorders such as uveitis, Sjögren’s syndrome, allergic conjunctivitis.

Anti-Inflammatory and Anti-Apoptotic Effects of Acer Palmatum Thumb. Extract, KIOM-2015EW, in a Hyperosmolar-Stress-Induced In Vitro Dry Eye Model.

The aim of this study was to assess the anti-inflammatory and anti-apoptotic effects of KIOM-2015EW, the hot-water extract of maple leaves in hyperosmolar stress (HOS)-induced human corneal epithelial cells (HCECs). HCECs were exposed to hyperosmolar medium and exposed to KIOM-2015EW with or without the hyperosmolar media. Tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 production and apoptosis were observed, and the activation of mitogen-activated protein kinases (MAPKs) including extracellular signal regulated kinase (ERK), p38 and c-JUN N-terminal kinase (JNK) signaling and nuclear factor (NF)-κB was confirmed. Compared to isomolar medium, the induction of cell cytotoxicity significantly increased in HCECs exposed to hyperosmolar medium in a time-dependent manner. KIOM-2015EW-treatment significantly reduced the mRNA and protein expression of pro-inflammatory mediators and apoptosis. KIOM-2015EW-treatment inhibited HOS-induced MAPK signaling activation. Additionally, the HOS-induced increase in NF-κB phosphorylation was attenuated by KIOM-2015EW. The results demonstrated that KIOM-2015EW protects the ocular surface by suppressing inflammation in dry eye disease, and suggest that KIOM-2015EW may be used to treat several ocular surface diseases where inflammation plays a key role.

This issue of ACTA, printed and electronic

This issue of <i><scp>ACTA</scp></i>, printed and electronic

Ocular surface inflammation in dry eye disease: What we know and what we do not.

Ocular surface inflammation in dry eye disease: What we know and what we do not.

Inflammation in Dry Eye Disease: How Do We Break the Cycle?

This article reviews the literature and summarizes the role of inflammation in dry eye disease. A PubMed search was performed using the keywords inflammatory cycle and dry eye. All searches were limited to articles published in or translated into the English language, dating from 1973 through March 2017. There were no restrictions on the study design. Advances in understanding the pathogenesis of dry eye disease has revealed that inflammation is a core driver: the so-called "vicious circle" of inflammation. Researchers continue to analyze the precise mechanisms by which inflammation occurs. This has led to therapeutic options to break the cycle. Continued animal and human studies reveal other potential sites for treatment in this complex host of disorders.

Clinical impact of inflammation in dry eye disease: proceedings of the ODISSEY group meeting.

Dry eye disease (DED) is a common, multifactorial ocular condition with major impact on vision and quality of life. It is now well recognized that the pathophysiology of chronic DED can include a cycle of inflammation involving both innate and adaptive immune responses. Recently, in vitro/in vivo models have been used to obtain a better understanding of DED‐related inflammatory processes at molecular/cellular levels although they do not truly reproduce the complex and chronic hallmarks of human DED. In clinical DED research, advanced techniques such as impression cytology, conjunctival biopsy, in vivo confocal microscopy and multiplex tear analyses have allowed an improved assessment of inflammation in DED patients. This was supported by the identification of reliable inflammatory markers including matrix metalloproteinase‐9, human leucocyte antigen‐DR or intercellular adhesion molecule‐1 in tears and impression cytology samples. One of the current therapeutic strategies focuses on breaking the inflammatory cycle perpetuating the ocular surface disease, and preclinical/clinical research has led to the development of promising anti‐inflammatory compounds. For instance, cyclosporine, already approved in the United States, has recently been authorized in Europe to treat DED associated with severe keratitis. In addition, other agents such as corticosteroids, doxycycline and essential fatty acids, through their anti‐inflammatory properties, show encouraging results. We now have a clearer understanding of the inflammatory processes involved in DED, and there is hope that the still emerging preclinical/clinical findings will be translated into new and highly effective therapies for patients in the near future.

Lifitegrast for the Treatment of Dry Eye Disease: Results of a Phase III, Randomized, Double-Masked, Placebo-Controlled Trial (OPUS-3)

Lifitegrast is a lymphocyte function-associated antigen-1 antagonist developed to reduce inflammation in dry eye disease (DED). We report the results of OPUS-3 (NCT02284516), a phase III study evaluating the efficacy and safety of lifitegrast versus placebo in participants with DED. Twelve-week, phase III, randomized, double-masked, multicenter, placebo-controlled study. Adults aged ≥18 years with Schirmer tear test (without anesthesia) ≥1 and ≤10 mm, corneal fluorescein staining score ≥2.0 (0-4 scale), eye dryness score (EDS) ≥40 (0-100 visual analogue scale [VAS]), and history of artificial tear use within 30 days of study entry. After a 14-day placebo run-in, participants were randomized 1:1 to lifitegrast ophthalmic solution 5.0% or placebo twice daily for 84 days. The primary efficacy end point was change from baseline to day 84 in EDS. Key secondary efficacy end points were change from baseline to days 42 and 14 in EDS. Other secondary efficacy end points included additional VAS items (burning/stinging, itching, foreign body sensation, eye discomfort, photophobia, pain), ocular discomfort score (ODS), and safety/tolerability of lifitegrast versus placebo. In the study, 711 participants were randomized: placebo, 356; lifitegrast, 355 (intention-to-treat [ITT] population). At day 84, lifitegrast-treated participants experienced significantly greater improvement from baseline in EDS versus those receiving placebo (treatment effect [TE], 7.16; 95% confidence interval [CI], 3.04-11.28; P= 0.0007). Mean changes from baseline in EDS also significantly favored lifitegrast on days 42 (TE, 9.32; 95%CI, 5.44-13.20; P < 0.0001) and 14 (TE, 7.85; 95% CI, 4.33-11.37; P < 0.0001). No statistically significant differences were observed in ODS between treatment groups at days 84, 42, or 14. A greater improvement was observed in lifitegrast-treated participants at day 42 in itching (nominal P= 0.0318), foreign body sensation (nominal P= 0.0418), and eye discomfort (P= 0.0048) versus participants receiving placebo. Most treatment-emergent adverse events were mild to moderate in severity; no serious ocular adverse events were reported. Lifitegrast significantly improved symptoms of eye dryness, as measured by EDS, versus placebo in participants with DED. Improvement in EDS was observed as early as day 14. Lifitegrast appeared well tolerated.

TSP-1 Deficiency Alters Ocular Microbiota: Implications for Sjögren's Syndrome Pathogenesis.

The potential role of commensals as triggering factors that promote inflammation in dry eye disease has not been explored. The objective of this study was to evaluate whether ocular microbiota changes with the onset of dry eye disease in thrombospondin-1-deficient (TSP-1(-/-)) mice, a strain that develops Sjögren's syndrome-like disease. Conjunctival swabs were collected from TSP-1(-/-) and C57BL/6 mice and analyzed for bacterial presence. Opsonophagocytosis of the bacterial conjunctival isolates derived from the aged TSP-1(-/-) mice by neutrophils derived from either TSP-1(-/-) or C57BL/6 bone marrow was evaluated. The bactericidal activities of TSP-1-derived peptide were examined. We found that in TSP-1(-/-) mice, the conjunctival colonization with Staphylococcus aureus and coagulase negative staphylococci sp (CNS) species was significantly increased with aging and preceded that of the wild-type C57BL/6 control mice. This correlated with increased neutrophil infiltration into the conjunctiva of the TSP-1(-/-) mice, suggesting that TSP-1 plays a significant role in regulating immunity to commensals. Accordingly, the TSP-1(-/-) PMNs opsonophagocytozed the ocular commensals less efficiently than the TSP-1-sufficient neutrophils. Furthermore, a TSP-1-derived peptide, 4N1K, exhibited significant antimicrobial activity when compared to a control peptide against commensal sp. These studies illustrate that alterations in the commensal frequency occur in the early stages of development of Sjögren's-like pathology and suggest that interventions that limit commensal outgrowth such as the use of TSP-1-derived peptides could be used for treatment during the early stages of the disease to reduce the commensal burden and ensuing inflammation.

Effects of l-Carnitine, Erythritol and Betaine on Pro-inflammatory Markers in Primary Human Corneal Epithelial Cells Exposed to Hyperosmotic Stress

Purpose: To explore the effects of osmoprotectants on pro-inflammatory mediator production in primary human corneal epithelial cells (HCECs) exposed to hyperosmotic stress.Methods: HCECs cultured in iso-osmolar medium (312 mOsM) were switched to hyperosmotic media with or without prior incubation with 2–20 mM of l-carnitine, erythritol or betaine for different time periods. The mRNA expression and protein production of pro-inflammatory markers in HCECs were evaluated by RT-qPCR and ELISA.Results: Hyperosmolar media significantly stimulated the mRNA and protein expression of pro-inflammatory cytokines, TNF-α, IL-1β and IL-6, and chemokines, IL-8, CCL2 and CCL20 in HCECs in an osmolarity dependent manner. The stimulated expression of these pro-inflammatory mediators was significantly but differentially suppressed by l-carnitine, erythritol or betaine. l-Carnitine displayed the greatest inhibitory effects and down-regulated 54–77% of the stimulated mRNA levels of TNF-α (down from 12.3–5.7 fold), IL-1β (2.2–0.9 fold), IL-6 (7.3–2.9 fold), IL-8 (4.6–2.0 fold), CCL2 (15.3–3.5 fold) and CCL20 (4.1–1.5 fold) in HCECs exposed to 450 mOsM. The stimulated protein production of TNF-α, IL-1β, IL-6 and IL-8 was also significantly suppressed by l-carnitine, erythritol and betaine. l-carnitine suppressed 49–79% of the stimulated protein levels of TNF-α (down from 81.3 to 17.4 pg/ml), IL-1β (56.9–29.2 pg/ml), IL-6 (12.8–4.6 ng/ml) and IL-8 (21.2–10.9 ng/ml) by HCECs exposed to 450 mOsM. Interestingly, hyperosmolarity stimulated increase in mRNA and protein levels of TNF-α, IL-1β and IL-6 were significantly suppressed by a transient receptor potential vanilloid channel type 1 (TRPV1) activation inhibitor capsazepine.Conclusions: l-carnitine, erythritol and betaine function as osmoprotectants to suppress inflammatory responses via TRPV1 pathway in HCECs exposed to hyperosmotic stress. Osmoprotectants may have efficacy in reducing innate inflammation in dry eye disease.

The role and treatment of inflammation in dry eye disease.

Dry eye syndrome is a common ocular surface problem, affects 10-30 % of the population, especially in those who are older than 40 years. As a consequence of the demographic pressure created by the aging population, its prevalence is expected to increase as well as its burden on ophthalmologic practices. Thus, understanding the complex underlying mechanisms and development of thoughtful, effective strategies that involve these mechanisms are critical. Many factors causing ocular surface damage and inflammation have been shown to contribute to the etiopathogenesis. Increased osmolarity induces ocular surface inflammation leading to disruption of both the quality and quantity of tears. Pathologic tear function and the ocular surface inflammation affects the neural arcade and increases apoptosis in the ocular surface cells thus creating a viscous cycle for dry eye by causing unstable and hyperosmolar tears. Thus, the treatment objective is to prevent severe dry eye complications via preventing inflammation and apoptosis of the ocular surface cells. The ultimate target is a normalized ocular surface, increased tear stability, and decreased osmolarity of the tear film. In the light of current literature, this review aims to elucidate the role of inflammation as the main etiological factor in dry eye disease and discuss current therapeutic approaches to overcome it.

The core mechanism of dry eye disease is inflammation.

The purpose of this article is to review the evidence for the hypothesis that the core mechanism of dry eye disease (DED) is inflammation, including evidence from recent basic, clinical, and translational research involving human patients, animal models, and cell cultures. Using the key words "dry eye + inflammation," the authors conducted a comprehensive search of the PubMed and Web of Science databases for scientific articles published in English between January 1, 1900 and August 30, 2013 on the role of inflammation in DED in cell cultures, animal models, and humans. The resulting articles were then categorized and reviewed. The literature search revealed a total of 458 publications, almost all published after 1992. The percentages of original studies and review articles are 77.29% (354) and 22.71% (104), respectively. Among the original studies, the number of reports on human DED is 200 (43.7%), on animal models is 115 (25.1%), and cell cultures is 39 (8.5%). A yearly distributing plot revealed that 76% were published from 2003 to 2011, 53% from 2008 to 2012, and 11% during the first 9 months of 2013. This distribution signifies a rapidly growing awareness of the importance of inflammation in DED pathogenesis. Inflammation plays a key role in the pathogenesis of DED as evidenced by research using tissue culture, animal models, and subjects with DED. Developing biomarkers for inflammation of the ocular surface will provide improved understanding of the mechanisms leading to DED, classification of the severity of DED, and objective metrics for outcome measures of treatment. The chronicity of the disease suggests that dysregulation of immune mechanisms leads to a cycle of continued inflammation, accompanied by alterations in both innate and adaptive immune responses. Given the underlying mechanism for DED, developing effective and safe anti-inflammatory treatments is likely to be beneficial for patients with DED.

The Influence of Benign Essential Blepharospasm on Dry Eye Disease and Ocular Inflammation

To study the influence of blepharospasm on dry eye disease by analyzing the clinical features, tear cytokine, and treatment response of patients with dry eye disease accompanied by benign essential blepharospasm. Prospective case series study. Forty adults with a diagnosis of benign essential blepharospasm (BEB) and dry eye disease (DED) were consecutively recruited. Forty subjects with dry eye disease only and 40 healthy adults were recruited as eligible controls. A tear specimen was collected from all participants for cytokine analysis. The patients with benign essential blepharospasm were treated with botulinum neurotoxin type A. The main outcome measures were the following: (1) Ocular Surface Disease Index (OSDI) questionnaire; (2) clinical features, including tear break-up time (BUT), Schirmer І test, and fluorescein staining; (3) conjunctival impression cytology; and (4) multiplex cytokine immunobead assay. The symptoms of DED+ BEB patients were significantly different from those of DED controls and healthy controls. Cytokine analysis in tear fluid also showed that tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-2, IL-17, and vascular endothelial growth factor levels were significantly increased in DED+ BEB patients. In treatment, botulinum neurotoxin type A injection effectively relieved blepharospasm in all of the DED+ BEB patients. Moreover, in this group of patients, OSDI decreased significantly after the botulinum neurotoxin type A injection, and BUT was increased as well. BEB may participate in the progress of inflammation in DED+ BEB patients. Botulinum neurotoxin type A injections could effectively relieve the symptoms of DED+ BEB patients and improve their ocular surface condition.

Ocular Surface Extracellular DNA and Nuclease Activity Imbalance: A New Paradigm for Inflammation in Dry Eye Disease

We determined whether nucleases are deficient in the tear fluid of dry eye disease (DED) patients, and whether this causes extracellular DNA (eDNA) and neutrophil extracellular trap (NET) accumulation in the precorneal tear film, thus causing ocular surface inflammation. Exfoliated cells adhered to Schirmer test strips were collected on glass slides, and immunofluorescence confocal microscopy was used to evaluate neutrophils, eDNA, NETs, and their molecular components. Similar experiments were performed with mucoid films collected from the inferior conjunctival fornix or bulbar conjunctiva. We used quantitative PCR to evaluate eDNA signaling pathways and inflammatory cytokine expression. We also determined the amount of ocular surface eDNA and evaluated tear fluid nuclease activity. eDNA, NETs, and neutrophils were present on the ocular surface in DED patients and abundant in mucoid films. NETs consisted of eDNA, histones, cathelicidin, and neutrophil elastase. Tear fluid nuclease activity was decreased significantly in DED patients, whereas the amount of eDNA on the ocular surface was increased significantly. Expression of genes downstream of eDNA signaling, such as TLR9, MyD88, and type I interferon, as well as the inflammatory cytokines interleukin-6 and tumor necrosis factor-α, was significantly increased in DED patients. Extracellular DNA production and clearance mechanisms are dysregulated in DED. Nuclease deficiency in tear fluid allows eDNA and NETs to accumulate in precorneal tear film, and results in ocular surface inflammation. These findings point to novel therapeutic interventions in severe DED based on clearance of eDNA, NETs, and other molecular components from the ocular surface.

The correlation between ocular surface inflammation and corneal fluorescein staining (CFS) in patients with moderate to severe dry eye disease (DED) participating in a randomized clinical trial

AbstractPurpose The relationship between ocular surface inflammation, signs and symptoms in DED remains poorly understood. A correlation between ocular surface inflammation and CFS in DED patients is reported.Methods DED patients with tear break up time ≤8 seconds and CFS grades 2‐4 modified Oxford scale and Schirmer test without anesthesia ≥2 and &lt;10 mm/5min and lissamine green staining, Van Bijsterveld &gt;4 and at least 1 dry eye symptom were randomized to CYCLOKAT® (unpreserved 0.1% cyclosporine cationic emulsion) or vehicle QD. Impression cytology for conjunctival HLA‐DR expression (an ocular surface inflammatory biomarker) was performed in a subset of patients.Results Cytology samples were collected in 89 of 492 patients. At baseline the mean HLA‐DR expression was higher in the CYCLOKAT® (84,345 AUF vs 46,888 AUF) arm. Notably, the mean HLA‐DR expression increased with baseline CFS grade (grade 2: 48,343; grade 3: 56,749; grade 4: 127,623). At month 6, CYCLOKAT® significantly reduced the HLA‐DR expression (‐50896 AUF vs ‐1192 AUF, p=0.022). The efficacy of CYCLOKAT® on improving CFS [as measured by mean change (delta of CYCLOKAT® over vehicle) and % achieving ≥ 2 grade improvement] increased with the CFS grade at baseline (grade 2‐4: 0.22 and 33.6% vs 21.8%, grades 3‐4: 0.32 and 40.4% vs 27.7%, grade 4: 0.77 and 48.8% vs 19.5%, p&lt;0.05 for all comparisons).Conclusion The demonstrated correlation between HLA‐DR expression and CFS support the role of inflammation in DED and justifies the need for anti‐inflammatory therapy. The benefit of CYCLOKAT® appears to be greatest in patients with severe DED. Commercial interest

The Role of Oxidative Stress and Inflammation in Dry Eye Disease

Abstract:There is a growing body of evidence to suggest that oxidative stress may be involved in at least the propagation of cellular injury that leads to eye pathology in various conditions including conjunctivochalasis, dry eye disease, age-related macular degeneration, and UV light-induced and to