Desiccating stress stimulates expression of matrix metalloproteinases by the corneal epithelium

Probiotic LB101 alleviates dry eye in mice by suppressing matrix metalloproteinase-9 expression through the regulation of gut microbiota-involved NF-κB signaling

Tear matrix metalloproteinase (MMP)-9 is an inflammatory signal in patients with dry eye (DE). In the present study, to understand the action mechanism of probiotic LB101 (Lactobacillus plantarum NK151 and Bifidobacterium bifidum NK175 [4:1] mix) against DE, we investigated its effect on tear amount and inflammatory marker expression levels in mice with unilateral exorbital lacrimal gland excision/atropine-benzalkonium chloride application (EB) or fecal microbiota transplantation from mice with EB (eFMT). Oral gavage of LB101 increased EB-suppressed tear amount and decreased EB-induced blinking number. Furthermore, LB101 decreased EB-induced TNF-α, IL-1β, and MMP-9 expression, TNF-α+ and NF-κB+CD11c+ cell populations, and edema in the conjunctiva, while EB-suppressed IL-10 and occludin expression increased. LB101 also decreased EB-induced TNF-α and IL-1β expression and NF-κB+CD11c+ cell population in the colon. eFMT also decreased tear amount and increased blinking number in the transplanted mice. eFMT increased TNF-α, IL-1β, and MMP-9 expression and TNF-α+ and NF-κB+CD11c+ cell populations in the conjunctiva and TNF-α and IL-1β expression and NF-κB+CD11c+ cell populations in the colon. Oral gavage of LB101 increased eFMT-suppressed tear amount and decreased eFMT-induced blinking number. Furthermore, LB101 decreased TNF-α, IL-1β, and MMP-9 expression, TNF-α+ and NF-κB+CD11c+ cell populations, and edema in the conjunctiva and TNF-α and IL-1β expression and NF-κB+CD11c+ cell population in the colon, while eFMT-suppressed IL-10 and occludin expression decreased. Furthermore, LB101 increased eFMT-suppressed Muribaculaceae, Prevotellaceae, and Lactobacillaceae populations in the gut microbiota, while eFMT-induced Bacteroidaceae population decreased. These findings suggest that DE may cause gut dysbiosis, which may be a risk factor for DE, and LB101 may alleviate DE with gut inflammation by suppressing the expression of MMP-9 and proinflammatory cytokines TNF-α and IL-1β with the regulation of gut microbiota-involved NF-κB signaling.

Expression of ATP-Binding Cassette Transporter A1 (ABCA1) in Eyelid Tissues and Meibomian Gland Epithelial Cells

Purpose

To validate the adenosine triphosphate (ATP)-binding cassette transporter A1 (ABCA1) expression and distribution in human eyelid tissues and meibomian gland epithelial cells.

Methods

Meibomian gland tissues from human eyelids were isolated by collagenase A digestion and cultured in defined keratinocyte serum-free medium (DKSFM). Infrared imaging was used to analyze the general morphology of meibomian glands. Hematoxylin and eosin (H&E) staining and Oil Red O staining were used to observe the morphological structure and lipid secretion in the human meibomian gland tissues. Quantitative real-time polymerase chain reaction, western blotting, and immunostaining were used to detect the mRNA and protein expression and cytolocalization of ABCA1 in the meibomian gland tissues and cultured cells.

Results

The degree of loss of human meibomian gland tissue was related to age. Meibomian gland lipid metabolism was also associated with age. Additionally, human meibomian gland tissues express ABCA1 mRNA and protein; glandular epithelial cells express more ABCA1 mRNA and protein than acinar cells, and their expression in acinar cells decreases with differentiation. Furthermore, the expression of ABCA1 was downregulated in abnormal meibomian gland tissues. ABCA1 was mainly localized on the cell membrane in primary human meibomian gland epithelial cells (pHMGECs), whereas it was localized in the cytoplasm of immortalized human meibomian gland epithelial cells (iHMGECs). The mRNA and protein levels of ABCA1 in pHMGECs were higher than those in iHMGECs.

Conclusions

Meibomian gland tissues of the human eyelid degenerate with age. ABCA1 expression in acinar cells decreases after differentiation and plays an important role in meibomian gland metabolism.

Transmembrane Protein CMTM6 Alleviates Ocular Inflammatory Response and Improves Corneal Epithelial Barrier Function in Experimental Dry Eye

Purpose

To investigate the impact of transmembrane protein CMTM6 on the pathogenesis of dry eye disease (DED) and elucidate its potential mechanisms.

Methods

CMTM6 expression was confirmed by database analysis, real-time polymerase chain reaction (RT-PCR), western blot, and immunohistochemistry. Tear secretion was measured using the phenol red thread test. Immune cell infiltration was assessed through flow cytometry. Barrier function was evaluated by fluorescein sodium staining, immunofluorescence staining of zonula occludens 1 (ZO-1), and electric cell-substrate impedance sensing (ECIS) assessment. For silencing CMTM6 expression, siRNA and shRNA were employed, along with lentiviral vector-mediated overexpression of CMTM6. Proinflammatory cytokine levels were analyzed by RT-PCR and cytometric bead array (CBA) analysis.

Results

CMTM6 showed high expression in healthy human and mouse corneal and conjunctival epithelium but was notably reduced in DED. Notably, this downregulation was correlated with disease severity. Cmtm6-/- dry eye (DE) mice displayed reduced tear secretion, severe corneal epithelial defects, decreased conjunctival goblet cell density, and upregulated inflammatory response. Additionally, Cmtm6-/- DE mice and CMTM6 knockdown human corneal epithelial cell-transformed (HCE-T) cells showed more severe barrier disruption and reduced expression of ZO-1. Knockdown of CMTM6 in HCE-T cells increased inflammatory responses induced by hyperosmotic stress, which was significantly mitigated by CMTM6 overexpression. Moreover, the level of phospho-p65 in hyperosmolarity-stimulated HCE-T cells increased after silencing CMTM6. Nuclear factor kappa B (NF-κB) p65 inhibition (JSH-23) reversed the excessive inflammatory responses caused by hyperosmolarity in CMTM6 knockdown HCE-T cells.

Conclusions

The reduction in CMTM6 expression on the ocular surface contributes to the pathogenesis of DED. The CMTM6-NF-κB p65 signaling pathway may serve as a promising therapeutic target for DED.

Comparison of matrix metallopeptidase-9 expression following cyclosporine and diquafosol treatment in dry eye

PURPOSE

We sought to evaluate the expression of matrix metalloproteinase-9 (MMP-9) in dry eyes treated with 0.05% cyclosporin A and 3.0% diquafosol tetrasodium.

METHODS

One-hundred ninety-five eyes of 195 patients with dry eye were divided into three groups as follows: group 1, cyclosporin group (n = 69); group 2, diquafosol group (n = 59); and group 3, artificial tears eyes (n = 67). All eyes were treated and followed up for three months. Schirmer I Test, corneal staining, tear-film break-up time (TBUT), and tear-film MMP-9 content were measured at three months and compared between groups. The expression of MMP-9 was confirmed using a point-of-care test device (InflammaDry®; RPS Diagnostics, Sarasota, FL, USA) and graded as zero to four points.

RESULTS

At the third month, MMP-9 expression was lower in group 1 as compared with in groups 2 and 3 (p = 0.020 and 0.006, respectively). The mean MMP-9 grade according to point-of-care testing was also lower in group 1 than in groups 2 or 3 (p = 0.002 and 0.038, respectively). MMP-9 showed a correlation with corneal staining in both groups 1 and 2 (all p < 0.001) and with Schirmer I Test and TBUT in group 1 (p = 0.018 and 0.015, respectively).

CONCLUSIONS

MMP-9 expression and grade were lower after treatment with cyclosporin than after treatment with diquafosol in the dry eye disease. Anti-inflammatory treatment can decrease ocular MMP-9 levels in dry eye disease.

New developments in the management of persistent corneal epithelial defects

A persistent epithelial defect (PED) is a corneal epithelial defect that failed to heal after 2weeks. It is a condition that carries much morbidity, and our understanding of PED remains poor, with current treatment methods often having unsatisfactory outcomes. With PEDs becoming more prevalent, more efforts are required to establish reliable treatment modalities. Our reviews describe the causes of PEDs and the different approaches developed to manage them, as well as their associated limitations. Emphasis is placed on understanding various advances in the development of new treatment modalities. We have also described a case of a woman with a background of graft-versus-host disease on long-term topical corticosteroids who developed complicated PED involving both eyes. The current approach to managing PEDs generally involves exclusion of an active infection, followed by treatment modalities that aim to encourage corneal epithelial healing. Success rates, however, remain far from desirable, as treatment remains challenging due to multiple underlying etiologies. In summary, advances in the development of new therapies may be able to facilitate progress in the understanding and treatment of PED.

Comparative Evaluation of Matrix Metalloproteinase-9 Immunoassay and Tear Osmolarity Measurement for Diagnosing Severity of Dry Eye Disease

PURPOSE

To evaluate and compare the clinical efficacy of matrix metalloproteinase-9 (MMP-9) immunoassay and tear osmolarity measurement in diagnosing dry eye severity.

METHODS

Dry eye disease (DED) patients underwent diagnostic tests including MMP-9 assay, tear osmolarity measurement, fluorescein tear breakup time, ocular surface staining, anesthetized Schirmer test, Ocular Surface Disease Index questionnaire, and slit-lamp examination. The dry eye parameters were compared according to positive MMP-9 status and increased tear osmolarity. The correlation between dry eye profiles and MMP-9 positivity and high tear osmolarity was also analyzed.

RESULTS

Those who tested positive in MMP-9 immunoassay had significantly higher corneal fluorescein staining score and worse DED severity than those who tested negative. The intensity of MMP-9 positivity showed positive correlation with the corneal staining score and DED severity. However, DED patients with high tear osmolarity above 308 mOsm/L did not show significantly different dry eye signs and symptoms compared to those with lower tear osmolarity values. Tear osmolarity was associated with ocular surface staining score in severe DED patients.

CONCLUSIONS

MMP-9 positivity was associated with ocular surface staining and worse dry eye severity. Therefore, it may be used as a useful indicator of disease severity in conjunction to other diagnostic tests.

Diagnostic Performance of the Tear Meniscus Osmolarity Measurement for Dry Eye Disease in Rheumatoid Arthritis Patients

BACKGROUND

The aim of our study was to evaluate the diagnostic capacity of the tear meniscus osmolarity measurement for dry eye disease (DED) in patients with rheumatoid arthritis (RA), using a portable osmometer based on electrical impedance and an integrated circuit technology (TearLab® (Escondido, CA, USA)).

METHODS

We included 101 RA patients, 81 patients with DED and 20 without DED (controls). We measured tear osmolarity and assessed other clinical diagnostic tests as suggested by the TFOS DEWS II composite reference standard diagnostic criteria for DED using Ocular Surface Disease Index (OSDI), Five-item Dry Eye Questionnaire (DEQ-5), fluorescein tear break-up time (F-TUBT), ocular surface staining (SICCA score), and other clinical parameters to classify DED subtypes. We analyzed the agreement between osmolarity and the TFOS DEWS II composite reference standard for DED diagnosis. We conducted receiver operating characteristic (ROC) curve analyses using the DED variable and its subtypes as dependent variables and the continuous variable for osmolarity or the inter-eye difference in osmolarity as independent variable. Sensitivity, specificity, and area under the curve for all potential cut-off points were obtained and reported from ROC curves.

RESULTS

We found that tear meniscus osmolarity had a low diagnostic capacity for DED (AUC = 0.57). Tear meniscus osmolarity measurement had a sensitivity of 35% and a specificity of 80% with a kappa level of agreement of 0.08 compared to the TFOS DEWS II composite reference standard. The low diagnostic capacity of the tear meniscus osmolarity was similar for aqueous-deficient DED and for evaporative DED, being only fair for severe DED with a 57% sensitivity and 80% specificity and a kappa level of agreement of 0.36.

CONCLUSIONS

Our findings suggest that in patients with RA, tear meniscus osmolarity measured by the TearLab® showed low sensitivity, low specificity, and limited agreement with the TFOS DEWS II composite reference standard for DED diagnosis.

The Effects of Sargassum horneri Extract and Fucoidan on Tear Hyposecretion and Ocular Surface Injury in Rats with Dry Eye Diseases

Hyperosmotic stress caused by tear hyposection is a leading cause of dry eye disease. We investigated the prevention of dry eye disease in corneal epithelial cells and in rats that were induced to develop dry eye disease via unilateral excision of their exorbital lacrimal gland using Sargassum horneri extract (AB_SH) and its bioactive component fucoidan. Oral administration of AB_SH (250 mg/kg and 500 mg/kg) and fucoidan (100 mg/kg) was conducted for 7 days. In order to measure tear secretion, phenol red thread tear tests were performed along with corneal irregularity measurements. The apoptotic injury in the cornea and the lacrimal gland was evaluated using TUNEL staining. AB_SH and fucoidan were shown to suppress apoptosis and the expression of apoptosis-related proteins in human corneal epithelial cells under hyperosmotic conditions. Oral administration of AB_SH and fucoidan attenuated tear hyposecretion and corneal irregularity in the lacrimal gland-excised rats. In addition, AB_SH and fucoidan also reduced apoptosis in the cornea and lacrimal gland. This study suggests that S. horneri extract and fucoidan can effectively ameliorate dry eye disease by suppressing the apoptosis of ocular tissues.

Transglutaminase-2 is critical for corneal epithelial barrier function via positive regulation of Claudin-1

PURPOSE

Transglutaminase (TG)-2 is a ubiquitous multi-functional protein expressed in all living cells. The purpose of the current study was to investigate the role of TG-2 in corneal barrier function and its potential regulation of epithelial junctional proteins and transcription factors.

METHODS

Corneal barrier function to ions in TG-2-/- and TG-2+/+ mice was assessed by Ussing chamber assay. Hypo-osmolar water or FITC-dextran was applied on top of mouse eyes to evaluate the corneal barrier function to water and macromolecules. Western blots, qPCR and immunofluorescent staining were used to investigate the expression of tight junction proteins in TG-2-/- and TG-2+/+ mouse corneas, and also in TG-2 knockdown human corneal epithelial cells.

RESULTS

Corneal explants from TG-2-/- mice had a lower trans-epithelial electrical resistance compared to TG-2+/+ mice. When challenged by hypo-osmolar water, the central corneal thickness of TG-2-/- mice increased faster, and these mice had a faster rise of fluorescence in the anterior chamber after ocular exposure to FITC-dextran, compared to TG-2+/+. Claudin-1 protein and transcript levels were reduced in the cornea of TG-2-/- mice and in TG-2 knockdown human corneal epithelial cells. Slug which previously reported suppressing Claudin-1 transcription, was increased at both protein and transcript level in TG-2 knockdown cells. TG-2 and Claudin-1 protein levels were unchanged in shRNA and shTG cells after MG132 treatment, while Slug accumulated in treated cells.

CONCLUSION

TG-2 may positively regulate Claudin-1 through repressing Slug at transcript level, and thus it is critical for normal corneal barrier function.

T-Cell Repertoire Analysis in the Conjunctiva of Murine Dry Eye Model

Purpose

Dry eye is closely related to the activation and proliferation of immune cells, especially T cells. However, the determination of the preferential T-cell clonotypes is technically challenging. This study aimed to investigate the characterization of T-cell receptor (TCR) repertoire in the conjunctiva during dry eye.

Methods

A desiccating stress animal model was established using C57/BL6 mice (8-10 weeks, female). After 7 days of stress stimulation, the slit-lamp image and Oregon-green-dextran staining were used to evaluate the ocular surface injury. Periodic acid-Schiff staining was used to measure the number of goblet cells. Flow cytometry was used to detect the activation and proliferation of T cells in the conjunctiva and cervical lymph nodes. Next-generation sequencing was used to detect the αβ TCR repertoire of the conjunctiva.

Results

The αβ TCR diversity increased significantly in the dry eye group, including the higher CDR3 amino acid length, marked gene usage on TCR V and J gene segments, extensive V(D)J recombination, and distinct CDR3 aa motifs. More important, several T-cell clonotypes were uniquely identified in dry eye. Furthermore, these perturbed rearrangements were reversed after glucocorticoid administration.

Conclusions

A comprehensive analysis of the αβ TCR repertoire in the conjunctiva of the dry eye mouse model was performed. Data in this study contributed significantly to the research on dry eye pathogenesis by demonstrating the TCR gene distribution and disease-specific TCR signatures. This study further provided some potential predictive T-cell biomarkers for future studies.

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.

Investigating the role of inflammation in keratoconus: A retrospective analysis of 551 eyes

PURPOSE

Keratoconus (KCN), classically defined as a noninflammatory corneal ectasia, was recently associated with chronic inflammation. This study aimed to further evaluate the association between inflammation and KCN severity by assessing patient tear films.

METHODS

Retrospective chart review of consecutive patients (July 2016-February 2020) referred to a tertiary KCN centre. Using tomography Kmax values, the worst-eyes of patients with a diagnosis of KCN and tear film test results were included. Eyes were stratified as matrix metalloproteinase-9 (MMP9) positive or negative and analyzed using independent t and Pearson chi-squared tests. A p-value ≤ 0.05 was considered significant.

RESULTS

551 (51.40%) unilateral eyes were included. Mean age was 30.1 years and 70.1% were male. 55.5% of the eyes were MMP9 positive. Mean corrected distance visual acuity was 20/30^<συπ>-3</sup> Snellen and Kmax was 60.1 Diopters. MMP9 positive eyes had a higher Kmax (p = 0.048), and were more likely from patients who were male (p < 0.001), had a paediatric history of asthma (p = 0.042), and used glasses (p = 0.041). MMP9 negative eyes more likely corresponded to soft contact lens users (p = 0.012). No other significant differences were found in risk factors, topography, tomography, and tear film osmolarity.

CONCLUSION

MMP9 positive keratoconic eyes had significantly higher Kmax readings which may correlate with increased disease severity, supporting an association between keratoconus and inflammation. Further research is warranted to evaluate the role of targeted therapy and contact lens use on MMP9 levels in keratoconic eyes and whether disease progression is affected.

Hyaluronan Modulates the Biomechanical Properties of the Cornea

Purpose

Hyaluronan (HA) is a major constituent of the extracellular matrix (ECM) that has high viscosity and is essential for maintaining tissue hydration. In the cornea, HA is enriched in the limbal region and is a key component of the limbal epithelial stem cell niche. HA is upregulated after injury participating in the formation of the provisional matrix, and has a key role in regulating the wound healing process. This study investigated whether changes in the distribution of HA before and after injury affects the biomechanical properties of the cornea in vivo.

Methods

Corneas of wild-type (wt) mice and mice lacking enzymes involved in the biosynthesis of HA were analyzed before, immediately after, and 7 and 14 days after a corneal alkali burn (AB). The corneas were evaluated using both a ring light and fluorescein stain by in vivo confocal microscopy, optical coherence elastography (OCE), and immunostaining of corneal whole mounts.

Results

Our results show that wt mice and mice lacking HA synthase (Has)1 and 3 present an increase in corneal stiffness 7 and 14 days after AB without a significant increase in HA expression and absence of scarring at 14 days after AB. In contrast, mice lacking Has2 present a significant decrease in corneal stiffness, with a significant increase in HA expression and scarring at 14 days after AB.

Conclusions

Our findings show that the mechanical properties of the cornea are significantly modulated by changes in HA distribution following alkali burn.

Glaucoma and Ocular Surface Disease: More than Meets the Eye

Understanding the association between ocular surface disease and glaucoma is important for improving adherence to treatment and introducing practical solutions. While topical antihypertensive medications for glaucoma are well tolerated according to short-term studies, there is little evidence on their long-term effects. Since they are often required for many years, the effects of these drops on the ocular surface become important in regard to quality of life and adherence. In this nonsystematic review performed in April 2022, we summarize what is known about the relationship between glaucoma and ocular surface disease. Specifically, we examine how each class of topical glaucoma drops affects the ocular surface. We then review the treatment of ocular surface disease for patients on topical glaucoma therapy. Finally, we discuss treatments that may reduce or eliminate the burden of topical medications.

Tear matrix metalloproteinase-9 levels may help to follow a ocular surface injury in lagophthalmic eyes

The preocular tear film is critically important for maintaining healthy ocular surface. In lagophthalmos, increased evaporation and tear film instability can occur. The level of tear matrix metalloproteinase 9 (MMP-9) is considered as a possible marker of ocular surface damage and inflammation. The aim of this study was to evaluate the possible usefulness of measuring tear film levels of MMP-9 in patients with lagophthalmos. Sixteen adult patients with unilateral lagophthalmos due to cerebellopontine angle mass surgery were included. Basic clinical examination including tear film osmolarity, degree of lagophthalmos, ocular surface sensitivity testing, corneal fluorescein staining, and tear break-up time (TBUT) were performed. Furthermore, tear MMP-9 quantification was performed and the values from lagophthalmic and contralateral healthy eye were compared. Possible correlations between tear MMP-9 levels and other parameters were analyzed. The Oxford score was higher in lagophthalmic eyes in comparison to healthy eyes. TBUT and corneal sensitivity were lower in lagophthalmic eyes. There was no difference in osmolarity between the two groups. Tear MMP-9 values were higher in lagophthalmic eyes. A higher MMP-9 value was associated with an increase in ocular surface fluorescein staining and a decrease of TBUT in lagophthalmic eyes. Tear MMP-9 may be used for monitoring ocular surface damage, contribute to early detection of inflammation progression and facilitate treatment adjustments.

Proteases and Their Potential Role as Biomarkers and Drug Targets in Dry Eye Disease and Ocular Surface Dysfunction

Dry eye disease (DED) is a multifactorial disorder that leads to ocular discomfort, visual disturbance, and tear film instability. DED is accompanied by an increase in tear osmolarity and ocular surface inflammation. The diagnosis and treatment of DED still present significant challenges. Therefore, novel biomarkers and treatments are of great interest. Proteases are present in different tissues on the ocular surface. In a healthy eye, proteases are highly regulated. However, dysregulation occurs in various pathologies, including DED. With this review, we provide an overview of the implications of different families of proteases in the development and severity of DED, along with studies involving protease inhibitors as potential therapeutic tools. Even though further research is needed, this review aims to give suggestions for identifying novel biomarkers and developing new protease inhibitors.

Porcine Corneas Incubated at Low Humidity Present Characteristic Features Found in Dry Eye Disease

Dry eye is a multifactorial disease that affects the ocular surface and tear fluid. Current treatment options include lubricant eye drop application several times a day. However, these eye drops often cause local side effects like ocular allergies or blurred vision after the application. To test new treatment options, a robust dry eye model is needed. Here, a porcine ex vivo model was established by means of incubation of porcine corneas in low humidity (LH) and characterized by histological damage evaluation, epithelial thickness and by relevant dry eye markers, such as interleukin 1 beta (IL-1β), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), occludin and galectin-3. In the dry eye model proposed, an increased secretion of IL-1β was observed, as well as an upregulation of NF-κB, occludin and galectin-3 mRNA expression. Moreover, the model presented a higher rate of cell death in comparison to the controls. These effects could be reversed with successful treatment of dexamethasone (dexa) and partially reversed with hyaluronic acid (HA) containing eye drops. Furthermore, medium-molecular-weight HA stimulated an increase in IL-1β in the model proposed. In conclusion, this dry eye model mimics the in vivo condition and hence allows for animal-free testing of novel dry eye treatments.

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.

Outcome Measures to Assess Dry Eye Severity: A Review

Outcome measures used to assess efficacy of dry eye therapeutics have not been consistently applied in clinical settings, nor have they been shown to correlate with functional outcomes. We propose that corneal staining, a clinically meaningful dry eye parameter, should be used as a standard objective outcome measure across all clinical trials evaluating dry eye treatments. We justify this based on evidence regarding its relationship to vision and vision related quality-of-life. In addition, corneal staining has been shown to correlate with ocular surface inflammation, a well elucidated aspect of dry eye pathophysiology and an active area in therapeutics research. No one outcome measure explored herein correlates perfectly to this heterogenous disease. However, there is mounting evidence showing the correlation between corneal staining and functional visual indices. We hope that future clinical trials will standardize corneal staining as a measure to determine the efficacy of interventions and justify their clinical utility.

Efficacy of topical cyclosporine 0.05% and osmoprotective lubricating eye drops in treating dry eye disease and inflammation

Purpose

To evaluate the effect of topical cyclosporine 0.05% and osmoprotective lubricating eye drops on patients with dry eye disease (DED) with inflammation as measured by raised tear matrix metalloproteinases (MMP-9).

Methods

This prospective study included 106 eyes of 53 patients diagnosed with DED based on any of the following DED criteria (Ocular Surface Disease Index [OSDI] score >12, tear film breakup time [TBUT] <10 s, Schirmer's I test result <10 mm/5 min, ocular surface staining). Ocular surface inflammation was assessed by assessing MMP-9 positivity from tears of the patients in the study (Inflammadry kit Quidel corporation). Patients were prescribed osmoprotective lubricating eye drops (Osmodrops, Cipla Ltd) four times a day and cyclosporine A 0.05% eye drops (Imudrops, Cipla Ltd) twice a day for 6 months. Efficacy of the formulations was evaluated by OSDI scores, Schirmer's test, TBUT change, reduction in ocular surface staining, and reduction in MMP-9 levels after 6 months of usage. Check P value and add from results.

Results

After 6 months of topical therapy, improvement was observed in OSDI scores (mean pretreatment: 25.7 ± 12.8, and mean posttreatment: 15.2 ± 8.4), P < 0.001. There was also reduction number of patients who were MMP-9 positive. Out of 75 eyes that tested MMP-9 positive, 70.66% showed reduction in MMP-9 levels P < 0.0001). Ocular surface staining also improved.

Conclusion

Topical osmoprotective lubricating eye drops and cyclosporine A 0.05% reduce inflammation in cases of DED, which correlates with improvement in OSDI scores, ocular surface staining, and reduction in inflammation as measured by levels of tear MMP-9.

Comparison of Two Experimental Mouse Dry Eye Models through Inflammatory Gene Set Enrichment Analysis Based on a Multiplexed Transcriptomic Approach

The goal of this study was to explore the specific signaling pathways related to inflammation in two experimental mouse dry eye (EDE) models. Female C57BL/6 mice housed for 10 days in a controlled desiccative environment were either treated with scopolamine (EDE-1; n = 18) or subjected to extraorbital lacrimal gland excision bilaterally (EDE-2; n = 10). Non-induced mice (n = 20) served as healthy controls. A corneal fluorescein staining (CFS) scoring was used at baseline through to day (D) 10 to evaluate epitheliopathy. At D10, corneas and conjunctivas were collected for multiplexed transcriptomic analysis with the NanoString^® mouse inflammatory CodeSet. Both EDE-1 and EDE-2 mice presented a change in corneal integrity, with a significant increase in CFS scores at D10. More gene transcripts were identified in EDE-2 compared with EDE-1 (116 vs. 96, respectively), and only a few were common to both models, 13 for the cornea and 6 for the conjunctiva. The gene functional annotation analysis revealed that the same inflammatory pathways were involved in both models. Comparative profiling of gene expression in the two EDE models leads to the identification of various targets and signaling pathways, which can be extrapolated to and confirmed in human disease.

Inducing dry eye disease using a custom engineered desiccation system: Impact on the ocular surface including keratin-14-positive limbal epithelial stem cells

PURPOSE

Dry eye disease (DED) is characterized by loss of tear film stability that becomes self-sustaining in a vicious cycle of pathophysiological events. Currently, desiccation stress (DS) is the dominant procedure for inducing DED in mice, however its' effect on limbal epithelial stem cells (LESCs) has been overlooked. This study aimed to establish a DS model via the use of a novel hardware to investigate the impact on the ocular surface including LESCs.

METHODS

A mouse transporter unit was customized to generate a dehumidified environment. C57BL/6J mice were exposed to mild DS and injected with scopolamine hydrobromide (SH) or remained untreated (UT) under standard vivarium conditions for 10 consecutive days (n = 28/group). Clinical assessments included phenol red tear-thread test, fluorescein staining and optical coherence tomography assessments. Histopathological and immunofluorescence was used to evaluate tissue architecture, goblet cell (GC) status, lacrimal gland (LG) inflammation and epithelial phenotype on the ocular surface. Whole flat-mounted corneas were immunostained for keratin-14 (K14), then imaged by confocal microscopy and analyzed computationally to investigate the effect of DS on LESCs.

RESULTS

Custom modifications made to the animal transporter unit resulted in dehumidified cage relative humidity (RH) of 43.5 ± 4.79% compared to the vivarium 53.9 ± 1.8% (p = 0.0243). Under these conditions, aqueous tear production in mice was suppressed whilst corneal permeability and corneal irregularity significantly increased. H&E staining indicated stressed corneal basal epithelial cells and increased desquamation. DS-exposed mice had reduced GC density (41.0 ± 5.10 GC/mm vs 46.9 ± 3.88 GC/mm, p = 0.0482) and LGs from these mice exhibited elevated CD4⁺ cell infiltration compared to controls. DS elicited K14⁺ epithelial cell displacement, as indicated by increased fluorescence signal at a distance of 50-100 μm radially inwards from the limbus [0.63 ± 0.053% (DS) vs 0.54 ± 0.060% (UT), p = 0.0317].

CONCLUSIONS

Application of mild DS using customized hardware and SH injections generated features of DED in mice. Following DS, ocular surface epithelial cell health decreased and LESCs appeared stressed. This suggested that potential downstream effects of DS on corneal homeostasis are present, a phenomenon that is currently under-investigated. The method used to induce DED in this study enables the development of a chronic model which more closely resembles disease seen in the clinic.

The artemisinin analog SM934 alleviates dry eye disease in rodent models by regulating TLR4/NF-κB/NLRP3 signaling

Dry eye disease (DED) is a multifactorial disorder of the tears and ocular surface characterized by manifestations of dryness and irritation. Although the pathogenesis is not fully illuminated, it is recognized that inflammation has a prominent role in the development and deterioration of DED. β-aminoarteether maleate (SM934) is a water-soluble artemisinin derivative with anti-inflammatory and immunosuppressive activities. In this study, we established scopolamine hydrobromide (SCOP)-induced rodent model as well as benzalkonium chloride (BAC)-induced rat model to investigate the therapeutic potential of SM934 for DED. We showed that topical application of SM934 (0.1%, 0.5%) significantly increased tear secretion, maintained the number of conjunctival goblet cells, reduced corneal damage, and decreased the levels of inflammatory mediators (TNF-α, IL-6, IL-10, or IL-1β) in conjunctiva in SCOP-induced and BAC-induced DED models. Moreover, SM934 treatment reduced the accumulation of TLR4-expressing macrophages in conjunctiva, and suppressed the expression of inflammasome components, i.e., myeloid differentiation factor88 (MyD88), Nod-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing CARD (ASC), and cleaved caspase 1. In LPS-treated RAW 264.7 cells, we demonstrated that pretreatment with SM934 (10 μM) impeded the upregulation of TLR4 and downstream NF-κB/NLRP3 signaling proteins. Collectively, artemisinin analog SM934 exerts therapeutic benefits on DED by simultaneously reserving the structural integrity of ocular surface and preventing the corneal and conjunctival inflammation, suggested a further application of SM934 in ophthalmic therapy, especially for DED.

Inhibition of matrix metalloproteinase-9 for the treatment of dry eye syndrome; a review study

Dry eye syndrome (DES) and tear dysfunction are multifactorial conditions affecting meibomian glands, lacrimal glands, and ocular surface. This ocular disorder can cause eye irritation, irregular cornea, corneal barrier disruption, and blurred vision. Uncontrolled increase in matrix metalloproteinase-9 (MMP-9) level and activity has been detected in the tears and ocular surface in the patients with DES, which has been proved to be related to disruption of tight junctions in apical corneal epithelium associated with severe signs of DES. These uncontrolled activities of MMP-9 lead to desquamation of ocular surface epithelia. Therefore, this review study was conducted to summarize the evidence regarding MMP-9 contribution in DES, and inhibition of MMP-9, as a therapeutic target for treatment of DES. For this purpose, herein, the related studies designed novel pharmaceutical compounds for direct and indirect inhibition of MMP-9 as treatment approaches for DES were reviewed. These compounds were designed to improve corneal barrier function, reduce inflammation on ocular surface, and restore tear production.

Short-Term Therapeutic Effects of Topical Corticosteroids on Refractory Dry Eye Disease: Clinical Usefulness of Matrix Metalloproteinase 9 Testing as a Response Prediction Marker

Purpose

To compare the short-term therapeutic effects of topical corticosteroids in patients with refractory dry eye disease (DED) according to the tear matrix metalloproteinase 9 (MMP-9) point-of-care positivity.

Methods

This study was conducted on 137 patients who were referred from other eye clinics, complaining of irresponsive DED or acute DED flares despite routine treatment with topical cyclosporin or diquafosol. The patients received treatment with topical corticosteroids for 1 month. DED was evaluated by SANDE (Symptom Assessment in Dry Eye) questionnaire, tear film breakup time, ocular surface staining score, and meibomian gland dysfunction stage. The InflammaDry MMP-9 immunoassay was conducted in more symptomatic eyes of all patients. The changes in the subjective symptoms were additionally surveyed as symptom improvement score.

Results

The mean age of the patients was 57.8±13.4 years, and the tear MMP-9 positivity was 73.0%. Topical corticosteroids treatment showed significant improvement of symptoms and signs in the patients with refractory DED irrespective of the positivity of MMP-9 (each p<0.001). The changes in SANDE score and OSS, and symptom improvement score were higher in the MMP-9 positive group than in the MMP-9 negative group (p=0.002/0.010/0.011). The overall rates of subjective symptoms improvement and SANDE reduction were 73.0% and 90.6% after topical corticosteroids treatment, respectively.

Conclusion

Short-term topical corticosteroids had excellent therapeutic effects in patients with refractory DED or acute DED flares, irrespective of the tear MMP-9 level. Tear MMP-9 positivity may serve as a reliable response predictor of topical corticosteroids treatment in DED.

Anatomical and physiological considerations in scleral lens wear: Eyelids and tear film

Scleral lenses can affect a range of anterior segment structures including the eyelids and the tears. The eyelids, consisting of the outer skin layer, the middle tarsal plate, and the posterior palpebral conjunctiva, provide physical protection and house the meibomian glands and cilia which have important and unique functions. Tears consist of a mix of aqueous, mucus, and lipidomic components that serve vital functions of lubricity, protection, and nourishment to the ocular surface. Both the eyelids and the tear film interact directly with scleral lenses on the eye and can affect but also be impacted by scleral lens wear. The purpose of this paper is to review the anatomy and physiology of the eyelids and tear film, discuss the effects and impacts of the scleral lenses on these structures, and identify areas that require further research.

Inflammatory basis for dry eye disease flares

Most patients with chronic dry eye disease (DED) have episodic flares, which can be triggered by a variety of activities and environmental stresses. These flares are typically associated with rapid exacerbation of discomfort symptoms, followed by prolonged elevation of inflammation. In an acute flare, ocular surface inflammation begins with a nonspecific innate immune response, in some cases followed by a slower but more specific adaptive immune response. At the ocular surface, epithelial cells are central to the innate immune response, and we discuss their role in DED flares alongside the other core components. Epithelial cells and other cells of the innate response (neutrophils, monocytes, macrophages and dendritic cells) trigger flares in response to increased osmolarity, detected via pattern receptors on their cell surface. Ultimately, downstream signaling pathways activate innate and adaptive immune responses, with consequent inflammation and symptoms. In chronic DED, pathogenic T cells have infiltrated the ocular surface tissues. The established adaptive immune response is likely to lead to flare-ups at lower thresholds of stress, with inflammation maintained over a longer period. Increased understanding of the inflammatory cascades activated during a flare may guide management and improve outcomes.

Alterations in corneal biomechanics underlie early stages of autoimmune-mediated dry eye disease

Autoimmune-mediated dry eye disease is a pathological feature of multiple disorders including Sjögren's syndrome, lupus and rheumatoid arthritis that has a life-long, detrimental impact on vision and overall quality of life. Although late stage disease outcomes such as epithelial barrier dysfunction, reduced corneal innervation and chronic inflammation have been well characterized in both human patients and mouse models, there is little to no understanding of early pathological processes. Moreover, the mechanisms underlying the loss of cornea homeostasis and disease progression are unknown. Here, we utilize the autoimmune regulatory (Aire)-deficient mouse model of autoimmune-mediated dry eye disease in combination with genome wide transcriptomics, high-resolution imaging and atomic force microscopy to reveal a potential extracellular matrix (ECM)-biomechanical-based mechanism driving cellular and morphological changes at early disease onset. Early disease in the Aire-deficient mouse model is associated with a mild reduction in tear production and moderate immune cell infiltration, allowing for interrogation of cellular, molecular and biomechanical changes largely independent of chronic inflammation. Using these tools, we demonstrate for the first time that the emergence of autoimmune-mediated dry eye disease is associated with an alteration in the biomechanical properties of the cornea. We reveal a dramatic disruption of the synthesis and organization of the extracellular matrix as well as degradation of the epithelial basement membrane during early disease. Notably, we provide evidence that the nerve supply to the cornea is severely reduced at early disease stages and that this is independent of basement membrane destruction or significant immune cell infiltration. Furthermore, diseased corneas display spatial heterogeneity in mechanical, structural and compositional changes, with the limbal compartment often exhibiting the opposite response compared to the central cornea. Despite these differences, however, epithelial hyperplasia is apparent in both compartments, possibly driven by increased activation of IL-1R1 and YAP signaling pathways. Thus, we reveal novel perturbations in corneal biomechanics, matrix organization and cell behavior during the early phase of dry eye that may underlie disease development and progression, presenting new potential targets for therapeutic intervention.

Matrix metalloproteinase 9 positivity predicts long term decreased tear production

PURPOSE

To investigate long-term correlations between Matrix Metalloproteinase-9 (MMP-9) testing and dry eye (DE) parameters. Additionally, to evaluate variability in MMP-9 results over time and with anti-inflammatory treatment.

METHODS

Retrospective cohort study of DE patients with equal MMP-9 testing results (positive or negative) in both eyes and a minimum of 6 months of follow up. Our main outcome measure was to examine whether initial MMP-9 status affected change in DE parameters over time. Secondarily, we evaluated the frequency of MMP-9 status change over time and examined whether MMP-9 status change was impacted by treatment.

RESULTS

67 patients (76% female) fit the inclusion criteria. Mean age was 63 years with a mean follow up of 10.6 months. The majority (37/67, 55%) had concomitant systemic immune disease. MMP-9 testing was positive in both eyes in 39 individuals (58%) and negative in both eyes in 27 (42%) individuals. Of all DE parameters, initial MMP status predicted change in tear production. Individuals in the MMP-9 positive group had a greater decrease in production from baseline to final visit compared to the negative group (-2.6 vs 2.1, P = 0.013). In those initially MMP-9 positive, the frequency of becoming MMP-9 negative was higher in eyes treated with anti-inflammatory therapy compared to artificial tears (22.9% vs 3.3%, P = 0.106). However, only Lifitegrast 5% showed statistical significance compared to artificial tears (31.3% vs 3.3%, P = 0.044).

CONCLUSIONS

Eyes with detectable MMP-9 had significantly decreased tear production over time compared to those without detectable MMP-9. Anti-inflammatory treatment more frequently normalized MMP-9 compared to PFATs.

A novel transillumination meibography device for in vivo imaging of mouse meibomian glands

PURPOSE

While mouse models of dry eye disease (DED) have been developed, studies evaluating the role of the meibomian glands limited by the inability to temporally document changes. In this report we describe the development of a novel mouse transillumination meibography device and assess the ability of this device to detect age-related changes in the meibomian glands of young and old mice.

METHODS

The mouse meibography device was comprised of a 3 mm wide right angle prism attached to broad spectrum light source by an optical fiber. Eyelids were then pulled over the prism using double tooth forceps and imaged using a stereomicroscope and low light level camera. Meibomian glands from four young and four old male, BALB/c mice were then imaged and analyzed using ImageJ.

RESULTS

In young mice, meibography documented the presence of 7-8 meibomian glands appearing as black and distinct eyelid structures with the length shorter in the lower eyelid compared to the upper eyelids. Eyelids of old mice showed apparent dropout of meibomian glands along with smaller and more irregularly shaped acini. The mean acini area of one meibomian gland was 0.088 ± 0.025 mm² in young mice and 0.080 ± 0.020 mm² in old mice (p = 0.564), but the Meibomian gland density was significantly lower in older mice (41.7 ± 6.4%, 27.3 ± 4.2%) (p = 0.021).

CONCLUSION

We have developed an in vivo meibography device that may prove useful in sequentially documenting changes during development of meibomian gland dysfunction and following treatment.

Biological functions of tear film

Tears have a vital function to protect and lubricate the ocular surface. Tear production, distribution and clearance is tightly regulated by the lacrimal functional unit (LFU) to meet ocular surface demands. The tear film consists of an aqueous-mucin layer, containing fluid and soluble factors produced by the lacrimal glands and mucin secreted by the goblet cells, that is covered by a lipid layer. The array of proteins, glycoproteins and lipids in tears function to maintain a stable, well-lubricated and smooth optical surface. Tear factors also promote wound healing, suppress inflammation, scavenge free radicals, and defend against microbial infection. Disease and dysfunction of the LFU leads to tear instability, increased evaporation, inflammation, and blurred and fluctuating vision. The function of tear components and the consequences of tear deficiency on the ocular surface are reviewed.

Loss of Concentration May Occur by Blink Inhibition in DED Simulation Models

Purpose: Patients with dry eye disease (DED) often suffer productivity loss and distress due to bothersome symptoms. The aim of this study was to objectively quantify and compare productivity-related emotional states obtained from brain waveforms in natural and simulated DED conditions. Method: 25 healthy adults (6 females and 19 males; mean age ± standard deviation, 22.6 ± 8.3 years) were recruited for the study, which included an electroencephalogram (EEG), measurements of interblinking time, and questionnaires. DED was simulated by suppressing blinking, while spontaneous blinking served as a control. Elements of concentration, stress, and alertness were extracted from the raw EEG waveforms and the values were compared during spontaneous and suppressed blinking. The relation with DED-related parameters was then explored. Written informed consent was obtained from all participants. Results: All participants successfully completed the experimental protocol. Concentration significantly decreased during suppressed blinking in 20 participants (80%), when compared with spontaneous blinking, whereas there were no or small differences in stress or alertness between spontaneous and suppressed blinking. The change in concentration was correlated with interblinking time (β = −0.515, p = 0.011). Conclusion: Loss of concentration was successfully captured in an objective manner using the EEG. The present study may enable us to understand how concentration is affected during blink suppression, which may happen in office work, particularly during computer tasks. Further study using detailed ocular evaluation is warranted to explore the effect of different interventions.

Scleral lens wear: Measuring inflammation in the fluid reservoir

PURPOSE

To measure inflammatory mediators in the scleral lens fluid reservoir (FR) in healthy eyes and to compare them to basal tear samples after 8-hs (8h) and 4-days (4d) of scleral lens (SL) wear.

METHODS

Fifteen normal, habitual soft contact lens wearers were fitted with 14.8- or 15.4-mm SLs (Zenlens, Alden Optical, USA). Basal ocular surface tears and FR samples were collected after 8h and 4d of daily SL wear. Levels of interleukin (IL) -4 and -8, matrix metalloproteinase (MMP)-7, -9, and -10, and tissue inhibitor of MMPs (TIMPs) 1-4 were measured in all samples using Luminex assays. Visual acuity, corneal and conjunctival staining, and comfort assessments were completed at the baseline, 8h and 4d time points.

RESULTS

MMP-9 and MMP-10 were greater in FR than basal ocular surface tears. After 8h of SL wear, the median concentration of MMP-9 in the FR and basal tears were 62.7 and 15.2 ng/mL, respectively (p = 0.047). Likewise, MMP-10 was significantly greater in FR compared to basal tears, after 8h (25.8 ng/mL vs 2.8 ng/mL, p < 0.001) and 4d (2.1 ng/mL vs17.2 ng/mL, p = 0.047). IL-4 and IL-8 levels were greater in FR but not significantly at 8h (2.2 vs 3.1 ng/mL; and 0.1 vs 0.4 ng/mL, respectively) or 4d (0.9 vs 3.5 ng/mL; 0.0 vs 0.2 ng/mL). MMP-7 was not affected by SL wear after 8h (46.0 basal vs 54.4 ng/mL FR) or 4d (34.2 vs 87.5 ng/mL). Visual acuity, corneal and conjunctival staining did not change; comfort was reduced in SL compared to soft contact lens wear.

CONCLUSIONS

This is the first study to compare the FR with the basal ocular surface tears. MMP-9 and MMP-10 were elevated in the FR after several hours of SL wear, suggesting potential clinical implications of SL wear and deserves further investigation.

Polydatin Inhibits NLRP3 Inflammasome in Dry Eye Disease by Attenuating Oxidative Stress and Inhibiting the NF-κB Pathway

Polydatin (also named pieceid, (E)-piceid, (E)-polydatin, trans-polydatin, or 3,5,4'-trihydroxystilbene-3-b-D-glucoside) is a monocrystalline compound isolated from the root and rhizome of Polygonum cuspidatum Sieb. et Zucc. (Polygonaceae). A previous study showed that polydatin has antioxidant and anti-inflammatory effects. However, the effect of polydatin in dry eye disease (DED) has not been elucidated. DED rat models were induced by exorbital lacrimal gland-excision. In vivo, the present study showed that the excision of lacrimal glands induced changes such as reduced tear fluid, severe corneal irregularity, damage, tear film break, and goblet cell loss as well as increased inflammation cytokine and NLRP3 expression in conjunctival tissue. However, these changes were restored by polydatin eye dropping. In vitro, polydatin inhibited hyperosmolar stress-induced inflammation through attenuation of the translocation of NF-κB to the nucleus and the mRNA expression of TNF-α, IL-6, IL-1β, and MMP9. In addition, the hyperosmolar stress-induced NLRP3 inflammasome pathway and ROS production were inhibited by polydatin. Our findings provided insight into the effect of polydatin as a candidate reagent for the treatment of DED.

Tear Film Osmolarity, Ocular Surface Disease and Glaucoma: A Review

Glaucoma is the second leading cause of blindness in the world, affecting more than 60 million people globally. In order to reduce the progression of the disease, both medical and surgical treatments are used. Frequent side effects of both treatments include a range of modifications of the ocular surface grouped as the Ocular Surface Disease (OSD), which include Dry Eye Disease (DED). DED and other OSD negatively impact on the success of anti-glaucoma treatments and reduce the adherence to medical therapies. Tear film osmolarity (TFO) is a relatively novel test which has become a hallmark of DED. The aim of this paper was to review the association between OSD, DED and glaucoma in view of published TFO data, and to discuss future fields of research and treatments on the topic of glaucoma iatrogenic damage.

Effects of Type 2 Diabetes Mellitus on Gene Expressions of Mouse Meibomian Glands

Purpose: Type 2 Diabetes mellitus (DM) is a major health problem and its ocular complications like orbital infections, cataract and diabetic retinopathy cause blindness. Meibomian gland (MG) dysfunction and dry eye disease are also important ocular complications of type 2 DM but not enough research has been conducted on these complications. Our hypothesis suggests type 2 DM can alter significant gene expressions of MG. In our study, MGs of leptin-deficient spontaneous diabetic and non-diabetic mice were extracted, and gene expression profiles were analyzed with microarray technology.Methods: Mice were divided into two groups; nine Lep ^b/ob spontaneous diabetic mice as type 2 DM group and nine non-diabetic Balb/c mice as controls. Blood glucose levels, tearfilm break-up time and fluorescein scores were measured in both two groups for 12 weeks. MGs were dissected and RNAs were isolated for microarray gene expression analysis. We filtered probes with standard deviation of more than 0.1 and we used 40452 of 45281 probes for processing. We performed fold change analysis and identified which genes are affected, and we analyzed the impact of genes on proteins, pathways and gene ontologies by using various databases.Results: We observed 172 up-regulated and 118 down-regulated genes in type 2 diabetic mice when compared to non-diabetic mice. Interestingly, expression of collagen type I, integrin beta-I binding protein-I, pyruvate dehydrogenase kinase, TNF receptor genes up-regulated with DM; on the other hand, IL-33, cholecystokinin, plasminogen activator, IL-1 and serine peptidase inhibitor genes down-regulated significantly. Also, we have seen a significant decrease in WNT signaling and pentose phosphate pathways-related genes.Conclusion: Our data show these changes in gene expression caused by endocrine and immune mechanisms of type 2 DM which result disrupted homeostasis of epithelial cells of MG. Increased expressions of apoptosis and inflammation-related genes and their effects on related pathways have proven that MGs were negatively affected by type-2 DM.

Trehalose augments autophagy to mitigate stress induced inflammation in human corneal cells

PURPOSE

Cornea acts as a structural barrier and protects the eye from environmental stresses. Inflammation in ocular surface causes discomfort and visual distortion. Defective autophagy has been associated with inflammation and ocular surface diseases. Therefore, we explored the protective role of trehalose on inflammation and desiccation-triggered stress in human corneal cells in vitro and in dry eye patients.

METHOD

TNF-α and desiccation stress induced human corneal cells (piHCF and HCE-T) with or without trehalose treatment were analyzed for the expression levels of inflammatory and autophagy related markers by qPCR, western blotting, multiplex ELISA and fluorescence imaging. Dry eye patients (N = 9) were enrolled and administered with trehalose in one eye and carboxymethylcellulose (CMC) in the contralateral eye (B.I.D, for 30 days). Dry eye signs OSDI, TBUT, Schirmer's Test, and tear cytokines were measured in dry eye patient's pre and post treatment.

RESULTS

Cells treated with trehalose exhibits increased levels of autophagy markers LC3II and LAMP1 compared to untreated cells. Trehalose reduced the mRNA and secreted cytokines levels of IL-6, IL-8 and MCP-1 in corneal cells under TNF-α and desiccation stress mediated inflammation compared to controls. Further, trehalose reduced stress driven p38 phosphorylation in corneal cells. Additionally, topical administration of trehalose alleviated the clinical symptoms and tears cytokine levels in dry eye patients compared to CMC.

CONCLUSION

Trehalose reduces stress induced inflammation through p38MAPK inhibition and autophagy activation. The anti-inflammatory mechanism of trehalose was independent to NFκB pathway. Further, topical administration of trehalose ameliorated dry eye associated symptoms and associated tear cytokines levels.

Corneal autophagy and ocular surface inflammation: A new perspective in dry eye

Dry eye disease (DED), a multifactorial ocular surface disorder affecting millions of individuals worldwide, is characterized by inflammation and damage to the ocular surface. It is unclear whether corneal autophagy participates in ocular surface inflammation observed in DED. To test this involvement, dry eye (DE) was induced in female C57BL/6 mice housed in a controlled environment by subcutaneous injection of scopolamine. Expression of the autophagy-related proteins LC3B and ATG5 and activation of autophagy were detected in the corneas of these mice. Treatment with LYN-1604, an activator of autophagy, alleviated the clinical indications in DE mice, including tear production and corneal fluorescence staining. LYN-1604 also reduced the corneal levels of inflammatory response products, including tumor necrosis factor alpha (TNF-α) and matrix metalloproteinases-3 and -9. By contrast, treatment of DE mice with the autophagy inhibitor 3-MA, exacerbated the clinical indications of DE and increased the levels of inflammatory response products. This is the first study to show that autophagy could regulate the level of ocular surface inflammation, suggesting that agents that regulate autophagy could relieve ocular surface inflammation and treat DED.

0.005% Preservative-Free Latanoprost Induces Dry Eye-Like Ocular Surface Damage via Promotion of Inflammation in Mice

Purpose

To investigate the side effects of preservative-free 0.005% latanoprost on the murine ocular surface.

Methods

We applied 0.005% latanoprost or vehicle in mice in two patterns for 14 to 28 days. Tear production was measured by phenol red cotton test, and corneal epithelial barrier function was assessed by Oregon-green-dextran (OGD) staining. Periodic acid-Schiff (PAS) staining was used to quantify conjunctival goblet cells (GCs). The expression of matrix metalloproteinase (MMP)-3 and -9, occludin-1 and zonula occludens (ZO)-1 in corneal epithelium was assessed by immunofluorescent staining and/or quantitative real-time PCR (qRT-PCR). Inflammation in conjunctiva was assessed by activation of P38 and NF-κB, infiltration of CD4+ T cells, and production inflammatory cytokines including TNF-α, IL-1β, IFN-γ, IL-17A, and IL-13. Apoptosis in ocular surface was assessed by TUNEL and immunofluorescent staining for activated caspase-3 and -8. Cell viability assay was performed in human corneal epithelial cells.

Results

Topical latanoprost treatment decreased tear production, induced conjunctival GC loss, disrupted the corneal epithelial barrier, and promoted cell apoptosis in the ocular surface. Topical latanoprost treatment increased the expression of MMP-3 and -9, and decreased the expression of ZO-1 and occludin-1 in the corneal epithelium. Topical application of latanoprost promoted activation of P38-NF-κB signaling and production of TNF-α and IL-1β in conjunctiva. Topical application of latanoprost increased CD4+ T cells infiltration, with increased production of IFN-γ and IL-17A and decreased production of IL-13 in conjunctiva.

Conclusion

0.005% latanoprost induced dry eye-like ocular surface damage via promotion of inflammation in mice.

MyD88 Deficiency Protects Against Dry Eye-Induced Damage

Purpose

Dry eye disease (DED) is a multifactorial disease associated with ocular surface inflammation. Toll-like receptors (TLRs) are integral in the initiation of inflammatory signaling. Therefore, we evaluated the effect of TLR-deficiency on dry eye–related ocular surface damage and inflammation using a mouse model of experimental dry eye (EDE).

Methods

C57BL/6 wild-type (WT), MyD88^−/−, and IL-1R^−/− mice were exposed to EDE conditions for 5 days. Tear production was measured by phenol red thread test and ocular surface damage assessed with fluorescein staining. Corneal homogenates were obtained for matrix metalloproteinase (MMP) and cytokine expression analysis by Luminex assay and quantitative PCR. In addition, whole eyes and eyelids were dissected and goblet cells and Meibomian glands were imaged, respectively.

Results

Following 5 days of EDE, WT mice had extensive ocular surface staining, while MyD88^−/− mice had no increased staining above non-EDE conditions. Similarly, MyD88^−/− mice did not have increased corneal MMP-2, 3, or 8 concentrations, as seen with WT mice. MyD88-deficiency also resulted in decreased corneal cytokine levels. In addition, MyD88^−/− mice had significantly lower conjunctival goblet cell counts compared with both WT (EDE) and IL-1R^−/− (non-EDE) mice. However, there was no difference in Meibomian gland morphology between WT, IL-1R^−/−, and MyD88^−/− mice.

Conclusions

These studies demonstrate the importance of TLR signaling in dry eye development. Mice lacking TLR signaling, MyD88^−/−, were protected from EDE-induced ocular surface damage and inflammatory mediator expression, warranting further investigation into TLR inhibition as a potential therapeutic for DED.

Chloroquine Protects Human Corneal Epithelial Cells from Desiccation Stress Induced Inflammation without Altering the Autophagy Flux

Dry eye disease (DED) is a multifactorial ocular surface disorder affecting millions of individuals worldwide. Inflammation has been associated with dry eye and anti-inflammatory drugs are now being targeted as the alternate therapeutic approach for dry eye condition. In this study, we have explored the anti-inflammatory and autophagy modulating effect of chloroquine (CQ) in human corneal epithelial and human corneal fibroblasts cells exposed to desiccation stress, (an in-vitro model for DED). Gene and protein expression profiling of inflammatory and autophagy related molecular factors were analyzed in HCE-T and primary HCF cells exposed to desiccation stress with and without CQ treatment. HCE-T and HCF cells exposed to desiccation stress exhibited increased levels of activated p65, TNF-α, MCP-1, MMP-9, and IL-6. Further, treatment with CQ decreased the levels of active p65, TNF-α, MCP-1, and MMP-9 in cells underdesiccation stress. Increased levels of LC3B and LAMP1 markers in HCE-T cells exposed to desiccation stress suggest activation of autophagy and the addition of CQ did not alter these levels. Changes in the phosphorylation levels of MAPKinase and mTOR pathway proteins were found in HCE-T cells under desiccation stress with or without CQ treatment. Taken together, the data suggests that HCE-T cells under desiccation stress showed NFκB mediated inflammation, which was rescued through the anti-inflammatory effect of CQ without altering the autophagy flux. Therefore, CQ may be used as an alternate therapeutic management for dry eye condition.

Matrix Metalloproteinase 9 Point-of-Care Immunoassay Result Predicts Response to Topical Cyclosporine Treatment in Dry Eye Disease

Purpose

We evaluate a matrix metalloproteinase-9 (MMP-9) point-of-care immunoassay (InflammaDry) as a prognostic tool for topical cyclosporine treatment.

Methods

A total of 20 healthy subjects and 40 patients meeting >3 dry eye disease (DED) criteria (ocular surface disease index [OSDI] score ≥ 12, tear film breakup time [TBUT] ≤10 seconds, Schirmer I test result ≤10 mm/5 minutes, corneal staining ≥1) were included. DED patients were treated with topical cyclosporine ophthalmic emulsion 0.05% twice daily for 1 month. The InflammaDry test was used to grade MMP-9 levels in the tear film. Treatment response was monitored using the OSDI score, TBUT, and Schirmer, corneal staining, and InflammaDry tests.

Results

Of the eyes, 18 (22.5%) were negative, 29 (36.3%) trace-positive, 16 (20.0%) weak-positive, 11 (13.8%) positive, and six (7.5%) strong-positive for MMP-9 at baseline. MMP-9 levels correlated with OSDI (P = 0.049), TBUT (P = 0.001), corneal staining (P = 0.002), and Schirmer test (P = 0.027) results. MMP-9–positive patients displayed decreased post-treatment MMP-9 levels (P = 0.001) and corneal staining score (P < 0.001), improved OSDI score (P < 0.001), and increased TBUT (P < 0.001) and Schirmer (P = 0.009) test values.

Conclusions

Semiquantitative MMP-9 grading correlated well with DED symptoms and signs, and could be used to predict patient status and monitor treatment response. MMP-9–positive patients responded more favorably to topical cyclosporine than did MMP-9–negative patients. Thus, the InflammaDry test may inform decisions regarding initiating topical cyclosporine treatment.

Translational Relevance

Semiquantitative MMP-9 could be used to predict patient status and monitor treatment response.

Suppression of Th1-Mediated Keratoconjunctivitis Sicca by Lifitegrast

PURPOSE

Increased interferon gamma (IFN-γ) expression in dry eye causes ocular surface epithelial disease termed keratoconjunctivitis sicca (KCS). The purpose of this study was to investigated the effects of the LFA-1 antagonist, lifitegrast, in a mouse desiccating stress (DS) dry eye model that develops KCS similar to Sjögren syndrome.

METHODS

Mice were treated with vehicle or lifitegrast twice daily for 5 days and expression of Th1 family genes (IFN-γ, CXCL9, and CXCL11) was evaluated by real-time polymerase chain reaction. Cornea barrier function was assessed by Oregon Green dextran staining and goblet cell number and area were measured.

RESULTS

Compared to the vehicle-treated group, the lifitegrast-treated group had significantly lower expression of Th1 family genes, less corneal barrier disruption, and greater conjunctival goblet cell density/area.

CONCLUSIONS

These findings indicate that lifitegrast inhibits DS-induced IFN-γ expression and KCS. This suggests that ICAM-LFA-1 signaling is involved with generation of Th1 inflammation in KCS.

Tear inflammatory mediators and protein in eyes of post allogenic hematopoeitic stem cell transplant patients

AIM

To analyze tear cytokines levels and their correlation to ocular surface parameters in allogenic hematopoietic stem cell transplants (allo-HSCT) patients.

METHODS

Prospective longitudinal study of allo-HSCT patients and controls for ocular surface evaluation (OSDI, TBUT, Schirmer's test, staining scores), tear biochemical analysis for protein, cytokines [IL-10, IL-12, IL-2, IL-4, IL-6, IL-17, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, VEGF], MMPs [MMP 2, 9, 7, 13, 10 and chemokine (IL-8)], & VEGF on three consecutive follow up visits (at three monthly interval) was done.

RESULTS

Of 24 post allo-HSCT patients (19 males, 5 females) & 12 controls (mean age 34.3 + 5.8 years) enrolled, 20 patients [mean age 33.4 + 7.77 years; mean time of recruitment of 5.2 + 2.12 months following alloHSCT] who completed three consecutive follow up visits were included for analysis. Ocular GVHD (oGVHD) was seen in 8 patients (33.3%). Tears biochemical analysis showed elevated levels of interferon γ, IL 6, IL 8, IL 10, IL 12AP70, IL 17A, MMP 9 and VEGF in oGVHD eyes as compared to non-oGVHD & control eyes. Non-oGVHD eyes showed elevated tear MMP 7 and MMP 9 as compared to healthy controls. Tear protein levels were significantly decreased in oGVHD eyes and were equivocal in nonGVHD and control eyes. TBUT and ocular staining scores to correlate best with tear interleukins and MMPs.

CONCLUSION

Evaluation of levels of tear VEGF, total protein & MMP 9 can be of significance in identifying oGVHD in post alloHSCT patients.