Inflammation In Dry Eye Disease Research Articles

ROS-responsive celastrol-nanomedicine alleviates inflammation for dry eye disease

Dry eye disease (DED) is a major global eye disease leading to severe eye discomfort and even vision impairment. The incidence of DED has been gradually increasing with the high frequency of use of electronic devices. It has been demonstrated that celastrol (Cel) has excellent therapeutic efficacy in ocular disorders. However, the poor water solubility and short half-life of Cel limit its further therapeutic applications. In this work, a reactive oxygen species (ROS) sensitive polymeric micelle was fabricated for Cel delivery. The micelles improve the solubility of Cel, and the resulting Cel loaded micelles exhibit an enhanced intervention effect for DED. The in vitro results demonstrated that Cel-nanomedicine had a marked ROS responsive release behavior. The results of in vitro and in vivo experiments demonstrated that Cel has excellent biological activities to alleviate inflammation in DED by inhibiting TLR4 signaling activation and reducing pro-inflammatory cytokine expression. Therefore, the Cel nanomedicine can effectively eliminate ocular inflammation, promote corneal epithelial repair, and restore the number of goblet cells and tear secretion, providing a new option for the treatment of DED.

Potential New Target for Dry Eye Disease-Oxidative Stress.

Dry eye disease (DED) is a multifactorial condition affecting the ocular surface. It is characterized by loss of tear film homeostasis and accompanied by ocular symptoms that may potentially result in damage to the ocular surface and even vision loss. Unmodifiable risk factors for DED mainly include aging, hormonal changes, and lifestyle issues such as reduced sleep duration, increased screen exposure, smoking, and ethanol consumption. As its prevalence continues to rise, DED has garnered considerable attention, prompting the exploration of potential new therapeutic targets. Recent studies have found that when the production of ROS exceeds the capacity of the antioxidant defense system on the ocular surface, oxidative stress ensues, leading to cellular apoptosis and further oxidative damage. These events can exacerbate inflammation and cellular stress responses, further increasing ROS levels and promoting a vicious cycle of oxidative stress in DED. Therefore, given the central role of reactive oxygen species in the vicious cycle of inflammation in DED, strategies involving antioxidants have emerged as a novel approach for its treatment. This review aims to enhance our understanding of the intricate relationship between oxidative stress and DED, thereby providing directions to explore innovative therapeutic approaches for this complex ocular disorder.

Biomarkers of oxidative stress and inflammation in dry eye disease

Biomarkers of oxidative stress and inflammation in dry eye disease

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.

Mitochondria-targeted SkQ1 nanoparticles for dry eye disease: Inhibiting NLRP3 inflammasome activation by preventing mitochondrial DNA oxidation

Dry eye disease (DED) is a multifactorial ocular surface disorder mutually promoted by reactive oxygen species (ROS) and ocular surface inflammation. NLRP3 is the key regulator for inducing ocular surface inflammation in DED. However, the mechanism by which ROS influences the bio-effects of NLRP3, and the consequent development of DED, largely remains elusive. In the present study, we uncovered that robust ROS can oxidate mitochondrial DNA (ox-mtDNA) along with loss of mitochondria compaction causing the cytosolic release of ox-mtDNA and subsequent co-localization with cytosolic NLRP3, which can promote the activation of NLRP3 inflammasome and stimulate NLRP3-mediated inflammation. Visomitin (also known as SkQ1), a mitochondria-targeted anti-oxidant, could reverse such a process by in situ scavenging of mitochondrial ROS. To effectively deliver SkQ1, we further developed a novel mitochondria-targeted SkQ1 nanoparticle (SkQ1 NP) using a charge-driven self-assembly strategy. Compared with free SkQ1, SkQ1 NPs exhibited significantly higher cytosolic- and mitochondrial-ROS scavenging activity (1.7 and 1.9 times compared to levels of the free SkQ1 group), thus exerting a better in vitro protective effect against H2O2-induced cell death in human corneal epithelial cells (HCECs). After topical administration, SkQ1 NPs significantly reduced in vivo mtDNA oxidation, while suppressing the expressions of NLRP3, Caspase-1, and IL-1β, which consequently resulted in better therapeutic effects against DED. Results suggested that by efficiently scavenging mitochondrial ROS, SkQ1 NPs could in situ inhibit DED-induced mtDNA oxidation, thus blocking the interaction of ox-mtDNA and NLRP3; this, in turn, suppressed NLRP3 inflammasome activation and NLRP3-mediated inflammatory signaling. Results suggested that SkQ1 NPs have great potential as a new treatment for DED.

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.

MicroRNAs of extracellular vesicles derived from mesenchymal stromal cells alleviate inflammation in dry eye disease by targeting the IRAK1/TAB2/NF-κB pathway

PurposeTo investigate the efficacy and mechanisms of human umbilical cord-derived MSC-derived extracellular vesicles (hucMSC-EVs) in a mouse model of desiccation-induced dry eye disease (DED). MethodshucMSC-EVs were enriched by ultracentrifugation. The DED model was induced by desiccating environment combined with scopolamine administration. The DED mice were divided into the hucMSC-EVs group, fluorometholone (FML) group, PBS group, and blank control group. Tear secretion, corneal fluorescein staining, the cytokine profiles in tears and goblet cells, TUNEL-positive cell, and CD4+ cells were examined to assess therapeutic efficiency. The miRNAs in the hucMSC-EVs were sequenced, and the top 10 were used for miRNA enrichment analysis and annotation. The targeted DED-related signaling pathway was further verified by using RT‒qPCR and western blotting. ResultsTreatment with hucMSC-EVs increased the tear volume and maintained corneal integrity in DED mice. The cytokine profile in the tears of the hucMSC-EVs group presented with a lower level of proinflammatory cytokines than PBS group. Moreover, hucMSC-EVs treatment increased goblet cell density and inhibited cell apoptosis and CD4+ cell infiltration. Functional analysis of the top 10 miRNAs in hucMSC-EVs showed a high correlation with immunity. Among them, miR-125 b, let-7b, and miR-6873 were conserved between humans and mice and were associated with the IRAK1/TAB2/NF-κB pathway that was activated in DED. Furthermore, IRAK1/TAB2/NF-κB pathway activation and the abnormal expression of IL-4, IL-8, IL-10, IL-13, IL-17, and TNF-α were reversed by hucMSC-EVs. ConclusionshucMSCs-EVs alleviate DED signs, suppress inflammation and restore homeostasis of the corneal surface by multitargeting the IRAK1/TAB2/NF-κB pathway via certain miRNAs.

Management of inflammation in dry eye disease: Recommendations from a European panel of experts.

Early initiation of anti-inflammatory therapies is recommended for dry eye disease (DED) to break the vicious cycle of pathophysiology. However, there is limited guidance on how to implement topical ciclosporin (CsA) and corticosteroid treatment into clinical practice. This expert-led consensus provides practical guidance on the management of DED, including when and how to use topical CsA. A steering committee (SC) of seven European DED experts developed a questionnaire to gain information on the unmet needs and management of DED in clinical practice. Consensus statements on four key areas (disease severity and progression; patient management; efficacy, safety and tolerability of CsA; and patient education) were generated based on the responses. The SC and an expanded expert panel of 22 members used a nine-point scale (1 = strongly disagree; 9 = strongly agree) to rate statements; a consensus was reached if ≥75% of experts scored a statement ≥7. A stepwise approach to DED management is required in patients presenting with moderate corneal staining. Early topical CsA initiation, alone or with corticosteroids, should be considered in patients with clinical risk factors for severe DED. Patient education is required before and during treatment to manage expectations regarding efficacy and tolerability in order to optimise adherence. Follow-up visits are required, ideally at Month 1 and every 3 months thereafter. Topical CsA may be continued indefinitely, especially when surgery is required. This consensus fills some of the knowledge gaps in previous recommendations regarding the use of topical corticosteroids and CsA in patients with DED.

AKR1C1 Protects Corneal Epithelial Cells Against Oxidative Stress-Mediated Ferroptosis in Dry Eye.

PurposeTo evaluate the precise mode of cell death and to investigate the molecular mechanism underlying the initiation of inflammation in dry eye disease (DED).MethodsC57BL/6 mice were injected with scopolamine subcutaneously and exposed to desiccating stress to establish a DED mouse model. An immortalized human corneal epithelial cell line (HCEC) was cultured under hyperosmolarity (500 mOsM). Protein expressions were measured using western blot assay and immunofluorescence staining. mRNA expression was analyzed by RNA-sequencing and quantitative RT-PCR. Transmission electron microscopy was used to observe the intracellular ultrastructure. Intracellular Fe2+ was detected by a FerroOrange fluorescent probe. Flow cytometry was used to evaluate the cellular reactive oxygen species and lipid peroxidation.ResultsMarked changes in ferroptosis-related markers expression, intracellular iron accumulation, and lipid peroxidation were observed in corneal epithelial cells of DED models. When excessive oxidative stress was suppressed, ferroptosis induced by hyperosmolarity in HCECs was restrained, as indicated by decreased iron content and lipid peroxidation levels. Moreover, AKR1C1 was upregulated by the activation of NRF2 in HCECs under hyperosmolarity. When AKR1C1 was knocked down, cell viability was decreased, accompanied by increased lipid peroxidation, whereas overexpression of AKR1C1 produced the opposite results. It was observed consistently that corneal defects and the inflammatory response were promoted after inhibition of AKR1C1 in vivo.ConclusionsExcessive oxidative stress-induced ferroptosis participates in DED pathogenesis. The expression of AKR1C1 is triggered by NRF2 to decrease ferroptosis-induced cell damage and inflammation in HCECs. These findings may provide potential makers targeting ferroptosis and AKR1C1 for DED therapy.

Corneal Epithelium-Derived Netrin-1 Alleviates Dry Eye Disease via Regulating Dendritic Cell Activation.

PurposeTo investigate the expression of corneal epithelium–derived netrin-1 (NTN-1) and its immunoregulatory function in dry eye disease (DED) using a DED mouse model.MethodsWe generated DED mouse models with desiccating stress under scopolamine treatment. RNA sequencing was performed to identify differentially expressed genes (DEGs) in the corneal epithelium of DED mice. NTN-1 expression was analyzed via real-time PCR, immunofluorescence staining, and immunoblotting. The DED mice were then treated with recombinant NTN-1 or neutralizing antibodies to investigate the severity of the disease, dendritic cell (DC) activation, and inflammatory cytokine expression.ResultsA total of 347 DEGs (292 upregulated and 55 downregulated) were identified in the corneal epithelium of DED mice: corneal epithelium–derived NTN-1 expression was significantly decreased in DED mice compared to that in control mice. Topical recombinant NTN-1 application alleviated the severity of the disease, accompanied by restoration of tear secretion and goblet cell density. In addition, NTN-1 decreased the number of DCs, inhibited the activation of the DCs and Th17 cells, and reduced the expression of inflammatory factors in DED mice. In contrast, blocking endogenous NTN-1 activity with an anti–NTN-1 antibody aggravated the disease, enhanced DC activation, and upregulated the inflammatory factors in the conjunctivae of DED mice.ConclusionsWe identified decreased NTN-1 expression in the corneal epithelium of DED mice. Our findings elucidate the role of NTN-1 in alleviating DED and impeding DC activation, thereby indicating its therapeutic potential in suppressing ocular inflammation in DED.

Inflammation and dry eye disease-where are we?

The presence of inflammation in dry eye disease (DED) results in increased patient symptomatology, ocular surface damage and worsening tear dysfunction. It also affects the health of meibomian glands and their secretions which further aggravates ocular surface disease. This article reviews current knowledge regarding ocular surface inflammation in DED and explores the relationships between the vicious cycles of DED, inflammation and meibomian gland dysfunction (MGD). The clinical evaluation of eyes with such changes, markers that identify the presence of inflammation on the ocular surface and current treatment options are discussed.

The Correlation between Matrix Metalloproteinase-9 Point-of-Care Immunoassay, Tear Film Osmolarity, and Ocular Surface Parameters.

Background Dry eye disease is a multifactorial disease that is difficult to diagnose due to multiple causative factors. The study aimed to evaluate the correlations between tear film matrix metalloproteinase-9 (MMP-9), tear film osmolarity, and ocular surface parameters in patients with dry eyes. Methods We performed a retrospective chart review for patients diagnosed with dry eye and investigated if associations existed amongst noninvasive tear breakup time (NIBUT); corneal staining scores; and MMP-9 grade, tear film osmolarity, and Schirmer's test I results. Results Twenty-four eyes of 24 patients were enrolled in the current study. The grade of MMP-9 (0–4) was positively correlated with tear film osmolarity (p=0.027). However, neither qualitative (positive or negative) nor quantitative (grade 0–4) measurements of MMP-9 correlated with any other ocular surface parameters. The osmolarity in the positive corneal staining group was significantly higher than that in the negative group (321.6 ± 19.261 and 299.89 ± 16.213, respectively; p=0.018). None of the other ocular surface parameters were correlated with tear film osmolarity. Conclusion Tear film MMP-9 may be an indicator for tear film osmolarity, or vice-versa. Moreover, osmolarity may have a correlation with corneal staining in patients with dry eye. Tear film MMP-9 and osmolarity tests can be helpful and convenient evaluation tools for identifying inflammation in dry eye disease in clinical practice.

TLR4-Dependent DUOX2 Activation Triggered Oxidative Stress and Promoted HMGB1 Release in Dry Eye.

Dry eye disease (DED) is one of the most common ocular surface diseases worldwide. DED has been characterized by excessive accumulation of reactive oxygen species (ROS), following significant corneal epithelial cell death and ocular surface inflammation. However, the key regulatory factor remains unclear. In this study, we tended to explore whether DUOX2 contributed to DED development and the underlying mechanism. Human corneal epithelial (HCE) cells were treated with hyperosmolarity, C57BL/6 mice were injected of subcutaneous scopolamine to imitate DED. Expression of mRNA was investigated by RNA sequencing (RNA-seq) and quantitative real-time PCR (qPCR). Protein changes and distribution of DUOX2, high mobility group box 1 (HMGB1), Toll-like receptor 4 (TLR4), and 4-hydroxynonenal (4-HNE) were evaluated by western blot assays and immunofluorescence. Cell death was assessed by Cell Counting Kit-8 (CCK8), lactate dehydrogenase (LDH) release, and propidium iodide (PI) staining. Cellular ROS levels and mitochondrial membrane potential (MMP) were analyzed by flow cytometry. RNA-seq and western blot assay indicated a significant increase of DUOX2 dependent of TLR4 activation in DED both in vitro and in vivo. Immunofluorescence revealed significant translocation of HMGB1 within corneal epithelial cells under hyperosmolar stress. Interestingly, after ablated DUOX2 expression by siRNA, we found a remarkable decrease of ROS level and recovered MMP in HCE cells. Moreover, knockdown of DUOX2 greatly inhibited HMGB1 release, protected cell viability and abolished inflammatory activation. Taken together, our data here suggest that upregulation of DUOX2 plays a crucial role in ROS production, thereafter, induce HMGB1 release and cell death, which triggers ocular surface inflammation in DED.

WAY-100635 Alleviates Corneal Lesions Through 5-HT1A Receptor-ROS-Autophagy Axis in Dry Eye.

Purpose: To explore whether 5-HT1A receptors are involved in the dry eye disease (DED) mouse model and reveal its underlying mechanism.Methods: A C57BL/6J mouse DED model was established via the administration of 0.2% benzalkonium chloride twice a day for 14 days. Corneal fluorescein sodium staining score and Schirmer I test were checked before, and on days 7, 14, and 21 after treatment. The experiment was randomly divided into control, DED, 5-HT1A receptor agonist with or without N-acetylcysteine (NAC) and 5-HT1A receptor antagonist with or without NAC groups. The mRNA expression of inflammatory cytokines was measured by reverse transcription-quantitative polymerase chain reaction. Cellular reactive oxygen species (ROS) were detected by 2', 7'-dichlorodihydrofluorescein diacetate assays. Western blot analysis was used to measure the expression levels of autophagic proteins microtubule-associated protein 1 light chain 3 (LC3B-I/II) and autophagy-related gene 5 (ATG5).Results: 5-HT1A receptor agonist (8-OH-DPAT) increased corneal fluorescein sodium staining spots and 5-HT1A receptor antagonist (WAY-100635) decreased them. Treatment with 8-OH-DPAT was associated with the gene expression of more inflammatory cytokines, such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), C-C motif chemokine ligand 2 (CCL2) and C-X-C motif chemokine ligand 10 (CXCL10) compared with treatment with WAY-100635. An increased expression of LC3B-I/II and ATG5 was observed in corneal epithelial cells in the mouse model of DED. 8-OH-DPAT significantly enhanced the expression of LC3B-I/II and ATG5 by disrupting ROS levels. WAY-100635 alleviates autophagy by inhibiting ROS production.Conclusion: Excessive ROS release through 8-OH-DPAT induction can lead to impaired autophagy and increased inflammatory response in DED. WAY-100635 reduces corneal epithelial defects and inflammation in DED, as well as alleviates autophagy by inhibiting ROS production. The activation of the 5-HT1A receptor-ROS-autophagy axis is critically involved in DED development.

Transdermal anti-inflammatory therapy for aqueous deficiency.

Lacrimal gland inflammation has been identified as an important limitation on aqueous production and associated dry eye disease. Ocular surface inflammation in dry eye disease can be a downstream response to reduced quantities of warmer hyperosmotic aqueous being delivered from an inflamed lacrimal gland with high concentrations of inflammatory mediators. This review examines evidence which shows how topical applications of anti-inflammatory drugs have very limited access to the lacrimal gland and an associated limited capacity to increase aqueous flow by reducing inflammation in the main lacrimal gland. Using cyclosporine as an exemplar immunomodulatory drug, this review examines problems associated with the topical administration of all anti-inflammatory drugs in the treatment of dry eye disease. Limited access to the lacrimal gland for topical applications and their very short on-eye residence times are compared with the therapeutic potential of prolonged therapeutic episodes that could be achieved with transdermal applications of a drug to the skin at the site of the lacrimal gland. Poor access to the lacrimal gland for topically administered drugs is a major barrier to the treatment of aqueous deficiency. While topical inflammatory drug access to the ocular surface is direct, poor access to the lacrimal gland is partly due to drop placement being downstream to the flow of aqueous (Eye Vis 2020;7:1; Eye Vis 2019;6:1). This barrier is much greater according to the degree that reflex tear flow is stimulated by irritation associated with adverse drop temperature, and/or pH and/or tonicity for example.

Integrin αv and Vitronectin Prime Macrophage-Related Inflammation and Contribute the Development of Dry Eye Disease

Cell signaling mediated by the αv integrin plays a pivotal role in macrophage activation in various inflammatory processes, but its involvement in the pathogenesis of dry eye disease (DED) remains unclear. In a murine model of DED, we found increased αv integrin expression in ocular surface macrophages. The αv integrins inhibitor c(RGDfK) ameliorated the corneal damage caused by DED, suggesting a pathogenic role for αv integrin. Because tear hyperosmolarity induces ocular inflammation in DED, a hyperosmolar culture of murine bone marrow-derived macrophages (BMDMs) is used to reproduce inflammation in vitro. However, the expression of proinflammatory cytokine mRNA was minimal, even though αv integrin was induced. In searching for components that are involved in αv integrin-mediated inflammation but that are missing from the culture model, we showed that the levels of vitronectin (VTN), a binding ligand of αv integrins, were increased in the tear fluid and conjunctival stroma of DED animals. The addition of VTN prominently enhanced hyperosmolarity-induced inflammation in BMDMs. Mechanistically, we showed that VTN/αv integrins mediated NF-κB activation to induce inflammatory gene expression in the BMDMs. Our findings indicate that interaction the of VTN with αv integrins is a crucial step in the inflammatory process in DED and suggests a novel therapeutic target.

A Retrospective Data Review Confirms That Topical Preservative-Free Hydrocortisone Improves Inflammation in Dry Eye Disease.

BackgroundInflammation is among the most important mechanisms in the pathogenesis of dry eye disease (DED), triggering the vicious circle of the disease. Reducing inflammation is an important target in dry eye disease treatment. Hydrocortisone is a low-potency corticosteroid with a low ocular penetration potential.AimTo document the effect of topical preservative-free hydrocortisone 0.335% (PFH, Softacort®, Laboratoires Théa, France) on DED.MethodsRetrospective data review of patients with mild to moderate DED, treated with PFH for 15 days. Clinical evaluations at Days 0 and 15 included the assessment of the central precorneal tear film thickness (CPTFT), fluorescein tear breakup time, Schirmer test, corneal grading staining (Oxford schema), ocular surface disease index (OSDI) spatial distribution of the precorneal tear film thickness, intraocular pressure (IOP) and local tolerance.ResultsData from 13 women and 2 men were collected. Mean age±SD was 51±5 years for women and 53±4 years for men. Clinical signs and symptoms significantly (all p<0.05) improved after 15 days of treatment. A significant positive correlation between the percentage of change in left eye CPTFT and that in the contralateral eye CPTFT was observed (p=0.003) as well as for both eyes and the left eye FTBUT (p=0.03). For the percentage of change in OSDI, the only significant correlation was with the percentage of change in right eye and FTBUT (p=0.03). IOP remained unchanged. No adverse events were recorded.ConclusionThis retrospective data review confirms that topical PFH twice daily for 2 weeks significantly improves clinical signs and symptoms in patients with mild to moderate DED with no safety issues.

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.

If Artificial Tears Aren't Enough. The Importance of Inflammatory Processes in Dry Eye Disease. Practical Aspects of an Anti-Inflammatory Therapy of Dry Eye Disease

Dry eye disease (DED) is a heterogenous disease of the ocular surface. Multiple pathogenetic factors are responsible for the disease process, but DED is generally linked to an increase in the osmolarity of the tear film and to inflammation of the ocular surface. The significance of inflammatory processes in DED is highlighted in the most recent definition of dry eye in the Dry Eye Workshop (DEWS). It is therefore critically important for the management of dry eye disease to understand the pathomechanisms and therapeutic options for the treatment of inflammatory processes. This review summarizes our current knowledge on Inflammation associated with DED and provides practical recommendations for the diagnosis and monitoring of the disease, as well as the use of currently available therapeutic options to counteract inflammation in DED.

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.