Measurement of inflammatory cytokines by multicytokine assay in tears of patients with glaucoma topically treated with chronic drugs

Benzalkonium chloride greatly deteriorates the biological activities of human corneal stroma fibroblasts in a concentration-dependent manner

BACKGROUND

Corneal tissues indirectly obtain nutritional needs and oxygen to maintain their homeostasis, and therefore, benzalkonium chloride (BAC) containing ocular instillations for medical therapy may, in turn, induce toxic effects more than expected in corneal tissues, especially the inside stroma layer.

METHODS

To evaluate the effects of very low concentrations (10-8%, 10-6%, or 10-4%) of BAC on human corneal stroma, we used two-dimensional (2D) cultures of human corneal stromal fibroblast (HCSF) cells and carried out the following analyses: (1) cell viability measurements, (2) Seahorse cellular bio-metabolism analysis, and (3) the expression of ECM molecules and endoplasmic reticulum (ER) stress-related molecules.

RESULTS

In the absence and presence of 10-8%, 10-6%, or 10-4% concentrations of BAC, cell viability deteriorated and this deterioration was dose-dependent. The results showed that maximal mitochondrial respiration was decreased, the mRNA expression of most of ECM proteins was decreased, and ER stress-related molecules were substantially and dose-dependently down-regulated in HCSFs by the BAC treatment.

CONCLUSIONS

The findings reported herein indicate that the presence of BAC, even at such low concentrations, is capable of causing the deterioration of cellular metabolic functions and negatively affecting the response to ER stress in HCSF cells resulting in a substantially decreased cellular viability.

Neuroprotective effects of resveratrol on retinal ganglion cells in glaucoma in rodents: A narrative review

Glaucoma, an irreversible optic neuropathy, primarily affects retinal ganglion cells (RGC) and causes vision loss and blindness. The damage to RGCs in glaucoma occurs by various mechanisms, including elevated intraocular pressure, oxidative stress, inflammation, and other neurodegenerative processes. As the disease progresses, the loss of RGCs leads to vision loss. Therefore, protecting RGCs from damage and promoting their survival are important goals in managing glaucoma. In this regard, resveratrol (RES), a polyphenolic phytoalexin, exerts antioxidant effects and slows down the evolution and progression of glaucoma. The present review shows that RES plays a protective role in RGCs in cases of ischemic injury and hypoxia as well as in ErbB2 protein expression in the retina. Additionally, RES plays protective roles in RGCs by promoting cell growth, reducing apoptosis, and decreasing oxidative stress in H2O2-exposed RGCs. RES was also found to inhibit oxidative stress damage in RGCs and suppress the activation of mitogen-activated protein kinase signaling pathways. RES could alleviate retinal function impairment by suppressing the hypoxia-inducible factor-1 alpha/vascular endothelial growth factor and p38/p53 axes while stimulating the PI3K/Akt pathway. Therefore, RES might exert potential therapeutic effects for managing glaucoma by protecting RGCs from damage and promoting their survival.

In vitro immunotoxicity effects of carbendazim were inhibited by n-acetylcysteine in microglial BV-2 cells

Carbendazim (CBZ) is a benzimidazole fungicide widely used worldwide in industrial, agricultural, and veterinary practices. Although, CBZ was found in all brain tissues causing serious neurotoxicity, its impact on brain immune cells remain scarcely understood. Our study investigated the in vitro effects of CBZ on activated microglial BV-2 cells. Lipopolysaccharide (LPS)-stimulated BV-2 cells were exposed to increasing concentrations of CBZ and cytokine release was measured by ELISA, and Cytometric Bead Array (CBA) assays. Mitochondrial superoxide anion (O2·-) generation was evaluated by Dihydroethidium (DHE) and nitric oxide (NO) was assessed by Griess reagent. Lipid peroxidation was evaluated by measuring the malonaldehyde (MDA) levels. The transmembrane mitochondrial potential (ΔΨm) was detected by cytometry analysis with dihexyloxacarbocyanine iodide (DiOC6(3)) assay. CBZ concentration-dependently increased IL-1β, IL-6, TNF-α and MCP-1 by LPS-activated BV-2 cells. CBZ significantly promoted oxidative stress by increasing NO, O2·- generation, and MDA levels. In contrast, CBZ significantly decreased ΔΨm. Pre-treatment of BV-2 cells with N-acetylcysteine (NAC) reversed all the above mentioned immunotoxic parameters, suggesting a potential protective role of NAC against CBZ-induced immunotoxicity via its antioxidant and anti-inflammatory effects on activated BV-2 cells. Therefore, microglial proinflammatory over-activation by CBZ may be a potential mechanism by which CBZ could induce neurotoxicity and neurodegenerative disorders.

Tear Protein Markers for Diabetic Retinopathy and Diabetic Macular Edema - Towards an Early Diagnosis and Better Prognosis

BACKGROUND

Diabetic eye disease is a highly prevalent and sight-threatening disorder. It is a disease of neuro-vascular unit of the retina, if left untreated can cause blindness. Therapeutic approaches followed for its treatment can only restrict the progression of the disease with highly variable results. There is no known biomarker for an early diagonsis of this disease, therefore by the time it is detected it goes beyond repair. This creates a massive demand for development of such biomarkers that help detect disease in its earlier stages.

METHODS

PUBMED (https://pubmed.ncbi.nlm.nih.gov/) was searched for articles relevant to the topic published till November 2023. The search was made using keywords such as Diabetic Retinopathy, inflammation, tear, biomarker, proteomics etc. The studies providing relevant information to prove the importance of biomarker discovery were chosen. After compiling the data, the manuscript writing was planned under relevant headings and sub-headings.

RESULTS

The review provides a comprehensive overview of all the tear protein biomarker studies in the field of DR and DME. Briefly, their potential in other diseases is also elucidated. While there are many studies pertaining to DR biomarkers, the identified markers lack validations which has restricted their usage in clinics. In case of DME, there was no such study towards biomarker discovery for its diagnosis and prognosis.

CONCLUSIONS

The review highlights major studies and their lacunae in the field of biomarkers discovery for DR and DME.

The Inflammatory and Cytological Effect of Repeated Povidone-Iodine Application in Patients Receiving Intravitreal Injections

OBJECTIVE

To investigate the effect of repeated povidone-iodine (PVI) application on the ocular surface parameters of patients who received intravitreal injections.

MATERIALS AND METHODS

In this prospective study, 52 eyes of 52 patients with age-related macular degeneration who underwent unilateral intravitreal injection at least three times in the last 1 year (intravitreal injection [IVI] group), 52 fellow eyes with no previous intravitreal injection (NIVI group), and 51 eyes of 51 healthy subjects (control) were included. Tear break-up time (TBUT), the Schirmer test, the Oxford staining score, the Ocular Surface Disease Index questionnaire, conjunctival impression cytology, and tear inflammatory cytokine levels (interleukin [IL]-1β and IL-6) were analyzed in all participants.

RESULTS

The IVI group had lower TBUT and higher Oxford staining score than the NIVI and control groups ( P <0.05). No significant difference was found between the groups in the Schirmer test ( P =0.161). Conjunctival impression cytology analysis revealed that the IVI group had a significantly lower goblet cell count and significantly higher Nelson staging result than the NIVI and control groups ( P <0.05). As a result of tear cytokine analysis, although IVI and NIVI groups had higher IL-1β and IL-6 levels than the control group ( P <0.05), there was no difference between NIVI and IVI groups ( P ≥0.05).

CONCLUSIONS

Repeated PVI application caused cytotoxic injury to the ocular surface, resulting in goblet cell loss and squamous metaplasia of epithelial cells. As a result, the stability of the tear film layer was found to be impaired and ocular surface-related symptoms developed in patients.

Comparative analysis of tear cytokines in patients with glaucoma, ocular hypertension, and healthy controls

PURPOSE

To investigate the ocular surface inflammation in patients with primary open angle glaucoma and ocular hypertension by analyzing tears and to compare findings with healthy controls.

METHODS

Observational case-control study. Tear samples were collected by 5 µl microcapillary tube from 24 patients with glaucoma treated by antiglaucoma drops, 9 non-treated patients with ocular hypertension and 45 healthy controls. Tears were analyzed from right eye by multiplex Bio-Plex system for the presence of 6 cytokines: IL1β, IL10, IL4, IFNγ, MIF and VEGF.

RESULTS

Significantly higher concentrations of IL1β and IL10 (glaucoma or ocular hypertension vs. healthy controls, p < 0.0001), VEGF (glaucoma vs. ocular hypertension, p < 0.05; ocular hypertension vs. healthy controls, p < 0.02) and MIF (glaucoma vs. healthy controls, p < 0.03) were detected in patients' tears. Both patient groups have activated to a significantly lower extent the Th1 pathway represented by IFNγ than Th2 pathway represented by IL10 (p < 0.001) and, at the same time, the IFNγ/IL4 ratio was significantly increased in healthy controls (p < 0.001) and patients with ocular hypertension (p < 0.02) compared to glaucoma individuals.

CONCLUSION

This study shows that secretion of inflammation-related cytokines by conjunctival cells is increased in both, glaucoma and ocular hypertension patients and can be detected in their tears. Nevertheless, data indicates stronger ocular surface inflammation in non-treated follow-up patients diagnosed with ocular hypertension than in glaucoma subjects treated by antiglaucoma drops.

The long-term mediation role of cytokines on the causal pathway from maternal gestational age to offspring eye diseases: Lifecourse-Network Mendelian randomization

BACKGROUND

Gestational duration has a significant impact on eye diseases. A large number of evidences suggest that cytokines are associated with gestational duration and eye diseases. However, the causal relationships among cytokines, maternal gestational impairment and offspring eye diseases remain unclear.

METHODS

We performed lifecourse-network Mendelian randomization (MR) to explore the causal relationships between maternal gestational duration (from the Early Growth Genetics (EGG) Consortium and the Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH) study, N = 84,689), neonatal/adult cytokines (from the NHGRI-EBI Catalog, N = 764/4,618), and adult eye diseases (from FinnGen consotium, N = 309,154) using summary-level data from large genome-wide association studies. Multiplicative random effects inverse variance weighted (IVW) and multivariable-IVW methods were the main analysis methods, and the other 15 pleiotropy-robust methods, weak IV-robust methods, and outliers-robust methods were used as auxiliary methods.

RESULTS

Maternal gestational age (early preterm birth, preterm birth, gestational duration, and post-term birth) had a causal relationship with 42 eye diseases. Four neonatal cytokines, Tumor Necrosis Factor-α(TNF-α), IL10, GROA, and CTACK, as well as four adult cytokines, CTACK, IL10, IL12p70 and IL6 are mediators in the causal relationships between early preterm birth and preterm birth in eight eye diseases. However, after adjusting for these mediators, a null direct causal effect of early preterm birth and preterm birth on eight eye diseases was found. In addition, there was no mediator in the causal relationship between gestational duration and post-term birth to eye diseases.

CONCLUSION

The effects of maternal gestational duration on offspring eye diseases through cytokines are long-term and life-course effects.

Changes in Tear Proteomic Profile in Ocular Diseases

The search for proteomic biomarkers in ocular disease is one of the most important research directions in recent years. Reliable biomarkers can be an immense adjuvant for both diagnostic and therapeutic approaches. There is no more readily available ocular tissue for proteomic analysis than tear film, which makes an interesting target for the biomarker search. Tear film is a complex fluid consisting of a superficial lipid layer, which covers the aqueous-mucous layer. Its complexity makes it a perfect candidate for all the "omics" approaches. Glaucoma, cataract, age-related macular degeneration, and other diseases are commonly thought to have a multifactorial background. Currently, no reliable non-invasive tests are available that would help physicians with screening and further patient management. The aim of the study is to present modern methods of measuring biomarkers in tears, with particular emphasis on spectrometric methods, and to discuss their diagnostic and therapeutic usefulness.

Benzalkonium Chloride, Even at Low Concentrations, Deteriorates Intracellular Metabolic Capacity in Human Conjunctival Fibroblasts

The objective of this study was to clarify the effects of benzalkonium chloride (BAC) on two-dimensional (2D) and three-dimensional (3D) cultures of human conjunctival fibroblast (HconF) cells, which are in vitro models replicating the epithelial barrier and the stromal supportive functions of the human conjunctiva. The cultured HconF cells were subjected to the following analyses in the absence and presence of 10⁻⁵% or 10⁻⁴% concentrations of BAC; (1) the barrier function of the 2D HconF monolayers, as determined by trans-endothelial electrical resistance (TEER) and FITC dextran permeability, (2) real-time metabolic analysis using an extracellular Seahorse flux analyzer, (3) the size and stiffness of 3D HconF spheroids, and (4) the mRNA expression of genes that encode for extracellular matrix (ECM) molecules including collagen (COL)1, 4 and 6, and fibronectin (FN), α-smooth muscle actin (α-SMA), ER stress related genes including the X-box binding protein-1 (XBP1), the spliced XBP1 (sXBP1) glucose regulator protein (GRP)78, GRP94, and the CCAAT/enhancer-binding protein homologous protein (CHOP), hypoxia inducible factor 1α (HIF1α), and Peroxisome proliferator-activated receptor gamma coactivator 1α (PGC1α). In the presence of BAC, even at low concentrations at 10⁻⁵% or 10⁻⁴%, the maximal respiratory capacity, mitochondrial respiratory reserve, and glycolytic reserve of HconF cells were significantly decreased, although the barrier functions of 2D HconF monolayers, the physical properties of the 3D HconF spheroids, and the mRNA expression of the corresponding genes were not affected. The findings reported herein highlight the fact that BAC, even such low concentrations, may induce unfavorable adverse effects on the cellular metabolic capacity of the human conjunctiva.

Two pediatric cases of reticular corneal epithelial edema associated with netarsudil

Purpose

To report two pediatric cases of reticular corneal epithelial edema associated with the use of netarsudil ophthalmic solution 0.02%.

Observations

In Case 1, a six-year-old male with glaucoma following cataract surgery was treated with netarsudil for thirteen months and developed diffuse reticular corneal epithelial edema on post-operative day one after undergoing transscleral diode cyclophotocoagulation for persistently elevated intraocular pressures. In Case 2, a three-month-old male with bilateral ocular hypertension developed unilateral inferior reticular corneal epithelial edema five weeks after initiation of netarsudil, which had been discontinued in the fellow eye two weeks prior. In both cases, the reticular epithelial edema resolved following cessation of netarsudil.

Conclusions and Importance

Netarsudil-associated reticular corneal epithelial edema can occur in infants and young children.

Clinical Tear Fluid Proteomics—A Novel Tool in Glaucoma Research

Tear fluid forms the outermost layer of the ocular surface and its characteristics and composition have been connected to various ocular surface diseases. As tear proteomics enables the non-invasive investigation of protein levels in the tear fluid, it has become an increasingly popular approach in ocular surface and systemic disease studies. Glaucoma, which is a set of multifactorial diseases affecting mainly the optic nerve and retinal ganglion cells, has also been studied using tear proteomics. In this condition, the complete set of pathophysiological changes occurring in the eye is not yet fully understood, and biomarkers for early diagnosis and accurate treatment selection are needed. More in-depth analyses of glaucoma tear proteomics have started to emerge only more recently with the implementation of LC-MS/MS and other modern technologies. The aim of this review was to examine the published data of the tear protein changes occurring during glaucoma, its topical treatment, and surgical interventions.

Age and sex-specific differences in interleukin 4, interferon gamma, macrophage migration inhibitory factor, and vascular endothelial growth factor levels in the tears of healthy subjects

OBJECTIVE

To investigate the physiological profile of pro-inflammatory and anti-inflammatory cytokines in tears produced by epithelial cells under the effect of endogenous and exogenous biological factors. Knowing the physiological cytokine profile in tears with its biological characteristics including sex- and age-specific effects is fundamental when tears are analyzed for diagnostic or prognostic purposes in eye diseases.

METHODS

Tear samples were collected from right eye of 45 healthy volunteers (24 males, 21 females) by 5 μl microcapillary tube. Cytokines interleukin 1β, interleukin 10, interleukin 4, interferon gamma, macrophage migration inhibitory factor, and vascular endothelial growth factor were quantified by multiplex Bio-Plex system.

RESULTS

The production of macrophage migration inhibitory factor cytokine by epithelial cells on the ocular surface is higher in males compared to females (p = 0.05); actually, most of female tear samples present with undetectable macrophage migration inhibitory factor levels. Our results show the negative correlations between the age and concentrations of interleukin 4 (p < 0.01) and interferon gamma (p < 0.01) in tears, respectively, and positive associations of vascular endothelial growth factor levels with the age above 45 years (p < 0.05).

CONCLUSIONS

Data in this study indicate that age and sex may affect the physiological levels of cytokines in tears. Consequently, the impacts of biological factors need to be recognized and taken into consideration before the levels of cytokines in patients' tears are analyzed for medical reasons. Concentrations of interleukin 1β and interleukin 10 cytokines, however, are very low in healthy tears and do not seem to be influenced by studied biological factors; therefore, they meet the requirements for analytes suitable for medical diagnostic and prognostic purposes.

The Efficacy and Safety of Preservative-containing and Preservative-free Brimonidine-Timolol Fixed Combination in Normal Tension Glaucoma

Purpose: To analyze the efficacy and safety of preservative-containing and preservative-free 0.2% brimonidine tartrate and 0.5% timolol maleate fixed combination drug in normal tension glaucoma.Methods: Fifty-one patients (84 eyes) who were diagnosed with normal tension glaucoma and with preservative-containing or preservative-free brimonidine-timolol fixed combinations alone were analyzed retrospectively from January 2017 to February 2020. Intraocular pressure (IOP) was measured four times a day (9 a.m., 11 a.m., 2 p.m., and 4 p.m.) before and at 6 months after applying eye drops. We analyzed and compared the effect of lowering IOP and the occurrence of intra or extra-ocular adverse effects.Results: A significant mean IOP reduction was shown in both groups: -1.95 ± 2.50 mmHg (-12.26 ± 15.87%) in the preservative-containing group and -1.60 ± 2.06 mmHg (-10.54 ± 13.94%) in the preservative-free group at 6 months after eyedrop instillation. The IOP was lowest in both groups at 11 a.m. There were no significant differences between the two groups in lowering IOP. Serious adverse effects causing discontinuation of the eye drops were not observed.Conclusions: Both preservative-containing and preservative-free brimonidine-timolol fixed combinations are effective in lowering IOP in normal tension glaucoma patients and are considered to be effective as eye drops without serious adverse effects.

Multiplex protein analysis for the study of glaucoma

INTRODUCTION

Glaucoma, a leading cause of irreversible blindness in the world, is a chronic neurodegenerative disease of multifactorial origin. Extensive research is ongoing to better understand, prevent, and treat progressive degeneration of retinal ganglion cells in glaucoma. While experimental models of glaucoma and postmortem tissues of human donors are analyzed for pathophysiological comprehension and improved treatment of this blinding disease, clinical samples of intraocular biofluids and blood collected from glaucoma patients are analyzed to identify predictive, diagnostic, and prognostic biomarkers. Multiplexing techniques for protein analysis offer a valuable approach for translational glaucoma research.

AREAS COVERED

This review provides an overview of the increasing applications of multiplex protein analysis for glaucoma research and also highlights current research challenges in the field and expected solutions from emerging technological advances.

EXPERT OPINION

Analytical techniques for multiplex analysis of proteins can help uncover neurodegenerative processes for enhanced treatment of glaucoma and can help identify molecular biomarkers for improved clinical testing and monitoring of this complex disease. This evolving field and continuously growing availability of new technologies are expected to broaden the comprehension of this complex neurodegenerative disease and speed up the progress toward new therapeutics and personalized patient care to prevent blindness from glaucoma.

Candidate Glaucoma Biomarkers: From Proteins to Metabolites, and the Pitfalls to Clinical Applications

Glaucoma is an insidious group of eye diseases causing degeneration of the optic nerve, progressive loss of vision, and irreversible blindness. The number of people affected by glaucoma is estimated at 80 million in 2021, with 3.5% prevalence in people aged 40-80. The main biomarker and risk factor for the onset and progression of glaucoma is the elevation of intraocular pressure. However, when glaucoma is diagnosed, the level of retinal ganglion cell death usually amounts to 30-40%; hence, the urgent need for its early diagnosis. Molecular biomarkers of glaucoma, from proteins to metabolites, may be helpful as indicators of pathogenic processes observed during the disease's onset. The discovery of human glaucoma biomarkers is hampered by major limitations, including whether medications are influencing the expression of molecules in bodily fluids, or whether tests to validate glaucoma biomarker candidates should include human subjects with different types and stages of the disease, as well as patients with other ocular and neurodegenerative diseases. Moreover, the proper selection of the biofluid or tissue, as well as the analytical platform, should be mandatory. In this review, we have summarized current knowledge concerning proteomics- and metabolomics-based glaucoma biomarkers, with specificity to human eye tissue and fluid, as well the analytical approach and the main results obtained. The complex data published to date, which include at least 458 different molecules altered in human glaucoma, merit a new, integrative approach allowing for future diagnostic tests based on the absolute quantification of local and/or systemic biomarkers of glaucoma.

Benzalkonium chloride-induced myofibroblastic transdifferentiation of Tenon's capsule fibroblasts is inhibited by coculture with corneal epithelial cells or by interleukin-10

Benzalkonium chloride (BAC) is used as a preservative in eyedrops but induces subconjunctival fibrosis that can result in failure of glaucoma surgery. Tenon's capsule fibroblasts in subconjunctival tissue interact with the corneal epithelium through tear fluid. With the use of a coculture system, we have now investigated the effect of human corneal epithelial (HCE) cells on myofibroblastic transdifferentiation of human Tenon fibroblasts (HTFs) induced by BAC (5 × 10^-6%). Immunofluorescence and immunoblot analyses revealed that the BAC-induced expression of α smooth muscle actin (αSMA) in HTFs was suppressed by coculture of these cells with HCE cells (p < 0.01). The concentration of interleukin-10 (IL-10) in culture supernatants of BAC-treated HTFs was increased by coculture with HCE cells (17.26-fold, vs. coculure, p < 0.001). Immunofluorescence and immunoblot analyses also showed that exogenous IL-10 (300 pg/ml) suppressed the BAC-induced expression of αSMA by 43.65% (p < 0.05) as well as the nuclear translocation of myocardin-related transcription factor-A (MRTF-A) by 39.32% (p < 0.01) in HTFs cultured alone. Our findings suggest that corneal epithelial cells may protect against subconjunctival fibrosis by maintaining IL-10 levels and preventing the MRTF-A-dependent transdifferentiation of HTFs into myofibroblasts.

Suggestive evidence of genetic association of -572G > C polymorphism with primary open angle glaucoma in a North Indian Punjabi population

BACKGROUND

IL6 is an important candidate gene implicated in the pathogenesis of glaucoma. The present study assessed the genetic association of -174G > C and -572G > C polymorphisms in the IL6 promoter region with primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) in a north Indian Punjabi cohort.

METHODS

910 subjects (313 POAG, 148 PACG cases and 449 controls) were recruited. Genotyping was done by TaqMan assays. Genetic association was tested under different genetic models using Plink. Diplotype and linkage disequilibrium (LD) analysis was done through Haploview. Association of clinical parameters with the genotypes was assessed by one-way ANOVA. Adjustment for potential confounding variables was done by binary logistic regression. IL6 levels were measured in POAG patients and controls.

RESULTS

572G > C variant showed marginal difference in genotype frequency between pooled cases and POAG subgroup with respect to controls (p = 0.042; OR = 1.33; and p = 0.041; OR = 1.37). The GC genotype conferred 1.37-fold protection under codominant model in POAG cases (p = 0.034, OR = 1.37, 95% CI = 1.02-1.85; p_corr = 0.025, OR = 1.45, 95% CI = 1.04-2.02). The mean value for IOP was elevated among cases having 'CC' genotype at the -572G > C locus (p = 0.037). Lower levels of IL6 were detected in POAG patients in plasma samples (p = 0.0001).

CONCLUSION

The study reports suggestive evidence for -572G > C variant in IL6 in affecting genetic susceptibility to POAG in the targeted North Indian Punjabi cohort. A correlation of IL6 levels in aqueous humor (AH) and systemic circulation in POAG was observed, the functional and diagnostic relevance of which may be further investigated.

Factors affecting the corneal endothelium after selective laser trabeculoplasty in primary open angle and angle closure glaucoma

Purpose

To study the factors affecting the corneal endothelium after selective laser trabeculoplasty (SLT) in primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG).

Method

This prospective interventional study included 56 patients (56 eyes) with POAG and 55 patients (55 eyes) with PACG. All participants received a standard SLT session. Patients with PACG were pretreated with laser peripheral iridotomy for at least 2 months before SLT. Corneal endothelium cell count (ECC), pleomorphism and polymegathism were measured before SLT, as well as at the increments of 1 hour, 1 day, 1 week, 1 month, 3 months and 6 months following SLT using confocal microscopy. A multiple regression analysis was applied to detect the factors affecting the ECC in the long-term post-SLT period.

Results

In both groups, the mean ECC significantly decreased from the baseline after SLT. While in POAG, corneal endothelium recovered within 1 month, in PACG, its damage persisted throughout the whole follow-up period.

According to the multiple analysis, baseline ECC (β=0.891, p=0.000 in POAG and β=0.706, p=0.000 in PACG) and age (β=−0.227, p=0.000 in POAG and β=−0.196, p=0.000 in PACG) were the common risk factors affecting ECC in both glaucoma forms, while the initial anterior chamber depth (β=0.254, p=0.000), only in PACG. The duration of glaucoma treatment (β=−0.317, p=0.043 in POAG and β=−0.302, p=0.047 in PACG) and pigmented deposits on the corneal endothelium in PACG (β=−0.326, p=0.019) were the risk factors determined in the univariate analysis.

Conclusion

Age and the baseline ECC are the risk factors for corneal endothelium damage after SLT in POAG and PACG. Shallow anterior chamber may affect corneal endothelium in PACG. These data should be considered when choosing an algorithm for glaucoma treatment.

Association of High-Mobility Group Box-1 with Inflammationrelated Cytokines in the Aqueous Humor with Acute Primary Angle-Closure Eyes

AIM

The aim of this study was to measure the levels of High-mobility group box-1 (HMGB1) and inflammation-related cytokines in the aqueous humor of patients with acute primary angle-closure glaucoma (APAG) and age-related cataract eyes (ARC).

METHODS

Aqueous humor samples were obtained from 59 eyes of 59 Chinese subjects (APAG, 32 eyes; and ARC, 27eyes). The multiplex bead immunoassay technique was used to measure the levels of HMGB1 and IL-8, IL-6, G-CSF, MCP-3, VEGF, sVEGFR- 1, sVEFGR-2, TNF-α, PDGF, and IL-10 in aqueous. The data of Patients' demographics and preoperative intraocular pressure (IOP) were also collected for detailed analysis.

RESULTS

The APAG group showed significantly elevated concentrations of HMGB1, IL- 8, IL-6, G-CSF, VEGF, sVEGFR-1, and TNF-α than those in the ARC group. Aqueous HMGB1 level correlated significantly with IOP, IL-8, IL-6, G-CSF and sVEGFR-1 levels but not with age, TNF-α, or VEGF levels.

CONCLUSION

The aqueous level of HMGB1 is elevated in APAG and associated with aqueous level of inflammation-related cytokines, suggesting an association between elevated levels of HMGB1, APAC and certain inflammatory modulators which, of course, should lead to further investigations in order to demonstrate the cause and effect.

Timolol induces necroptosis, apoptosis and senescence concentration-dependently in rabbit Limbal stem cells in vitro

Limbal stem cells (LSCs) are crucial for corneal transparency and vision. Any damages to LSCs might lead to limbal stem cell deficiency resulting in corneal opacification and even blindness. Here, we investigated the cytotoxicity of timolol and its underlying mechanisms in rabbit LSCs (rLSCs) in vitro. High concentrations of 0.5% and 0.25% timolol induced necroptosis in rLSCs to upregulate receptor interacting protein kinase (RIPK)1, RIPK3, mixed lineage kinase domain-like (MLKL) and phosphorylated MLKL along with downregulation of caspase-8 and caspase-2 within 4 h. While, median concentrations of 0.125% to 0.0625% timolol induced apoptosis in the rLSCs within 28 h. The apoptotic mechanism in the median-concentration timolol-treated rLSCs is probably via extrinsic apoptosis pathway by activating caspase-2, caspase-8 and caspase-3 and intrinsic apoptosis pathway triggered by excessive generation of ROS and subsequent DNA damage to upregulate Bax and Bad, downregulate Bcl-2 and Bcl-xL, subsequently disrupt mitochondrial membrane potential, cytosolically translocate cytochrome c and apoptosis-inducing factor, and activate caspase-9. In addition, low concentration of 0.03125% timolol induced senescence in the rLSCs by elevating ROS level and increasing number of senescence associated β-galactosidase positive cells at 28 h. Our findings reveal that timolol induces necroptosis, apoptosis and senescence concentration-dependently in rLSCs in vitro.

Inflammation in Glaucoma: From the back to the front of the eye, and beyond

The pathophysiology of glaucoma is complex, multifactorial and not completely understood. Elevated intraocular pressure (IOP) and/or impaired retinal blood flow may cause initial optic nerve damage. In addition, age-related oxidative stress in the retina concurrently with chronic mechanical and vascular stress is crucial for the initiation of retinal neurodegeneration. Oxidative stress is closely related to cell senescence, mitochondrial dysfunction, excitotoxicity, and neuroinflammation, which are involved in glaucoma progression. Accumulating evidence from animal glaucoma models and from human ocular samples suggests a dysfunction of the para-inflammation in the retinal ganglion cell layer and the optic nerve head. Moreover, quite similar mechanisms in the anterior chamber could explain the trabecular meshwork dysfunction and the elevated IOP in primary open-angle glaucoma. On the other hand, ocular surface disease due to topical interventions is the most prominent and visible consequence of inflammation in glaucoma, with a negative impact on filtering surgery failure, topical treatment efficacy, and possibly on inflammation in the anterior segment. Consequently, glaucoma appears as an outstanding eye disease where inflammatory changes may be present to various extents and consequences along the eye structure, from the ocular surface to the posterior segment, and the visual pathway. Here we reviewed the inflammatory processes in all ocular structures in glaucoma from the back to the front of the eye and beyond. Our approach was to explain how para-inflammation is necessary to maintain homoeostasis, and to describe abnormal inflammatory findings observed in glaucomatous patients or in animal glaucoma models, supporting the hypothesis of a dysregulation of the inflammatory balance toward a pro-inflammatory phenotype. Possible anti-inflammatory therapeutic approaches in glaucoma are also discussed.

Profiling ocular surface responses to preserved and non-preserved topical glaucoma medications: A 2-year randomized evaluation study

BACKGROUND

Use of topical glaucoma medications has been reported to cause ocular surface (OS) discomfort and inflammation. This study explores the profile of inflammatory cytokines and OS symptoms induced in response to preserved and non-preserved drops.

METHODS

Prospective, randomized evaluation on 36 treatment-naïve patients over 24 months of three differently preserved glaucoma drop preparations: Preservative-free (PF), polyquad (PQ) and benzalkonium chloride (BAK). Study participants were evaluated at baseline and then at 1, 3, 6, 12 and 24 months while on medication. At each visit, participants completed the OS disease index (OSDI) questionnaire, had basal tear sampling and impression cytology (IC) of the conjunctival epithelium. Quantitative polymerase chain reaction was performed to measure the gene expression of inflammatory cytokines [interleukin (IL)-6, IL-8, IL-10, IL-12A, IL-12B, IL-17A, IL-1β and tumour necrosis factor-α] in the IC samples. Corresponding protein expression of cytokines in tear samples was assessed by the Becton-Dickinson cytometric bead arrays.

RESULTS

Compared to PF and PQ groups, mRNA and protein expression of IL-6, IL-8 and IL-1β increased in samples from the BAK group in a time-dependent fashion, whereas all other cytokines showed a non-significant increase. In the BAK group, there was a strong correlation between OSDI and the levels of IC/IL-1β (r = .832, R² = .692 and P = .040); IC/IL-10 (r = .925, R² = .856 and P = .008) and tear/IL-1β (r = .899, R² = .808 and P = .014).

CONCLUSIONS

BAK-preserved topical drops stimulate a sterile inflammatory response on the OS within 3 months which is maintained thereafter, whereas PF-drops and PQ-preserved drops showed no significant OS inflammation.

Discovery and clinical translation of novel glaucoma biomarkers

Glaucoma and other optic neuropathies are characterized by progressive dysfunction and loss of retinal ganglion cells and their axons. Given the high prevalence of glaucoma-related blindness and the availability of treatment options, improving the diagnosis and precise monitoring of progression in these conditions is paramount. Here we review recent progress in the development of novel biomarkers for glaucoma in the context of disease pathophysiology and we propose future steps for the field, including integration of exploratory biomarker outcomes into prospective therapeutic trials. We anticipate that, when validated, some of the novel glaucoma biomarkers discussed here will prove useful for clinical diagnosis and prediction of progression, as well as monitoring of clinical responses to standard and investigational therapies.

Factors Predetermining Increased Aqueous Humour Flare in Long-Term Glaucoma Treatment

Glaucoma patients often require long-term or even lifelong medical antiglaucomatous treatment. Benzalkonium chloride (BAK) is the most frequently used preservative in medical glaucoma treatment. Laser flare photometry is the noninvasive quantitative measurement of anterior chamber protein level and helps tracking intraocular inflammation. The purpose of our study was to evaluate the ocular aqueous humour flare in glaucoma patients, scheduled for cataract surgery without any other ocular diseases, and the association with pseudoexfoliation (PEX) syndrome, number of medications used, and BAK. A prospective case-control age- and gender-matched study, including open-angle glaucoma patients (>2 years of treatment) with cataract, matched with cataract patients with no other ocular pathology (control group). We found that the aqueous humour flare was higher in the glaucoma group than in the control group. PEX syndrome increased the aqueous humour flare independently from glaucoma diagnosis. The number of used antiglaucomatous medications correlated moderately with the aqueous humour flare. The BAK index showed weak positive correlation with aqueous humour flare. A variety of factors can affect aqueous humour flare increase, including PEX syndrome, medical substance used to treat glaucoma, number of different medications, and presence of BAK. The combination of these factors is of key importance to long-term glaucoma treatment.

The Innate Immune Cell Profile of the Cornea Predicts the Onset of Ocular Surface Inflammatory Disorders

Ocular surface inflammatory disorder (OSID) is a spectrum of disorders that have features of several etiologies whilst displaying similar phenotypic signs of ocular inflammation. They are complicated disorders with underlying mechanisms related to several autoimmune disorders, such as rheumatoid arthritis (RA), Sjögren’s syndrome, and systemic lupus erythematosus (SLE). Current literature shows the involvement of both innate and adaptive arms of the immune system in ocular surface inflammation. The ocular surface contains distinct components of the immune system in the conjunctiva and the cornea. The normal conjunctiva epithelium and sub-epithelial stroma contains resident immune cells, such as T cells, B cells (adaptive), dendritic cells, and macrophages (innate). The relative sterile environment of the cornea is achieved by the tolerogenic properties of dendritic cells in the conjunctiva, the presence of regulatory lymphocytes, and the existence of soluble immunosuppressive factors, such as the transforming growth factor (TGF)-β and macrophage migration inhibitory factors. With the presence of both innate and adaptive immune system components, it is intriguing to investigate the most important leukocyte population in the ocular surface, which is involved in immune surveillance. Our meta-analysis investigates into this with a focus on both infectious (contact lens wear, corneal graft rejection, Cytomegalovirus, keratitis, scleritis, ocular surgery) and non-infectious (dry eye disease, glaucoma, graft-vs-host disease, Sjögren’s syndrome) situations. We have found the predominance of dendritic cells in ocular surface diseases, along with the Th-related cytokines. Our goal is to improve the knowledge of immune cells in OSID and to open new dimensions in the field. The purpose of this study is not to limit ourselves in the ocular system, but to investigate the importance of dendritic cells in the disorders of other mucosal organs (e.g., lungs, gut, uterus). Holistically, we want to investigate if this is a common trend in the initiation of any disease related to the mucosal organs and find a unified therapeutic approach. In addition, we want to show the power of computational approaches to foster a collaboration between computational and biological science.

Structural and Molecular Tear Film Changes in Glaucoma

The Tear Film (TF) is a trilaminar and dynamic fluid covering the entire Ocular Surface (OS), consisting of a mucus, aqueous, and lipid layer deeply interacting between them. Because of its structure and functions, TF plays a pivotal role in the preservation of the OS integrity and the quality of vision. Medical therapy for glaucoma is recognized to profoundly disturb the OS homeostasis by altering all components of the ocular surface unit, including TF. The presence of preservatives, the number of daily eye drops instillations, and the duration of therapy are the main contributors to TF changes. From the physio-pathological side, TF alterations are induced by toxic and allergic mechanisms and result from goblet cell and Meibomian gland loss, dysfunction of accessory lacrimal glands, and epithelial disruption. In detail, TF changes are represented by mucus layer thinning, reduced mucin concentration, aqueous layer volume reduction, and lipid layer thinning with increased tear evaporation. Hyper- osmolarity and instability represent the main hallmarks of these changes and are an expression of a iatrogenic form of dry eye. TF undergoes also molecular modifications that primarily reflect a therapy- or disease-induced inflammatory status of the OS. Over the last years, this field of research aimed a progressively growing interest since molecular variations may be considered as potential candidate biomarkers of glaucoma. The aim of this review is to report the main TF changes occurring during glaucoma, exploring the relationship they may have with the glaucoma-related ocular surface disease and the patient quality of life, and their utility as potential biomarkers of disease.

Tear Film, Conjunctival and Corneal Modifications Induced by Glaucoma Treatment

Ocular surface disease is characterized by tear film instability and histopathologic and clinical changes of the ocular surface. Glaucoma patients often suffer from ocular surface disease caused by the chronic use of preserved medical treatment to reduce intraocular pressure. Benzalkonium chloride is the preservative most frequently used in glaucoma medications. Its effect on tear film, conjunctiva and cornea and the consequences in glaucoma management are discussed in this mini-review.

Mapping mRNA Expression of Glaucoma Genes in the Healthy Mouse Eye

Purpose/Aim: Many genes have been associated with primary open-angle glaucoma (POAG). Knowing exactly where they are expressed in the eye helps to unravel POAG pathology and to select optimal targets for intervention. We investigated whether RNA in situ hybridization (RNA-ISH) is a convenient technique to obtain detailed pan-ocular expression data of these genes. We tested this for four diverse candidate POAG genes, selected because of unclear ocular distribution (F5 and Dusp1) and relevance for potential new therapies (Tnf, Tgfβr3). Optn, a POAG gene with well-known ocular expression pattern served as control. Methods: We made a list of candidate glaucoma genes reported in genetic studies. A table of their ocular expression at the tissue level was compiled using publicly available microarray data (the ocular tissue database). To add cellular detail we performed RNA-ISH for Optn, Tnf, Tgfβr3, F5, and Dusp1 on eyes of healthy, 2-month-old, pigmented, and albino mice. Results: Expression of the Optn control matched with published immunohistochemistry data. Ocular expression of Tnf was generally low, with patches of higher Tnf expression, superficially in the corneal epithelium. F5 had a restricted expression pattern with high expression in the nonpigmented ciliary body epithelium and moderate expression in the peripapillary region. Tgfβr3 and Dusp1 showed ubiquitous expression. Conclusions: RNA-ISH is a suitable technique to determine the ocular expression pattern of POAG genes, adding meaningful cellular detail to existing microarray expression data. For instance, the high expression of F5 in the nonpigmented ciliary body epithelium suggests a role of this gene in aqueous humor dynamics and intraocular pressure. In addition, the ubiquitous expression of Tgfβr3 has implications for designing TGF-β-related glaucoma therapies, with respect to side effects. Creating pan-ocular expression maps of POAG genes with RNA-ISH will help to identify POAG pathways in specific cell types and to select targets for drug development.

Comparative analysis of cytokine profiles of glaucomatous tears and aqueous humour reveals potential biomarkers for trabeculectomy complications

Glaucoma is a multifactorial neurodegenerative disease that causes impaired vision and, in advanced cases, blindness. The increasing prevalence of glaucoma due to an ageing population has necessitated the identification of suitable biomarkers for the early detection of the disease. Aqueous humour (AH) has been proposed as a source of biomarkers, but it can only be collected using a minor, yet invasive surgical intervention. Tears, however, are constantly available and can be collected any time via noninvasive methods. In order to examine the utility of tear as a surrogate for aqueous humour in biomarker development, we compared the levels of 27 cytokines and chemokines in paired samples of tear and aqueous humour using a Luminex multiplex immunobead-based technique. Significantly higher levels of cytokines in tear compared to aqueous humour were detected suggesting that tear and aqueous humour are not identical in terms of inflammation response. Furthermore, the levels of IFN-γ, GM-CSF and IL-5 in tear were significantly lower in patients who developed complications after one year, but no statistically significant changes in cytokine levels were observed in aqueous humour. These three molecules may have potential as predictive biomarkers for the appearance of late flap-related complications of trabeculectomy.

Neutrophil to Lymphocyte and Platelet to Lymphocyte Ratios in Normal Tension Glaucoma

Normal tension glaucoma (NTG) is a subtype of glaucoma that occurs at relatively low intraocular pressure levels and results in progressive optic neuropathy. Previous studies display some abnormal immune activity against the optic nerve. Neutrophil to lymphocyte (NLR) and platelet to lymphocyte ratios (PLR) are novel markers for inflammation. Here we evaluated the NLR, PLR, Creactive protein (CRP) and erythrocyte sedimentation rate (ESR) levels in NTG. NLR and PLR were resulted by dividing neutrophil and platelet counts to lymphocyte count respectively. Patients with a history of diabetes mellitus, chronic renal failure, rheumatologic disease, anemia, cancer, cigarette smoking, myocardial infarction and a febrile illness within one month of sampling were excluded from the investigation. In total, the blood samples of 28 NTG and 27control patients were analyzed for the study. There were 11 female (40.7%) and 16 male patients (59.3%) in the control group. The NTG group contained 15 (53.6%) female and 13 (46.4%) male patients. All of the NLR, PLR, ESR and CRP, values of NTG patients were not statistically different from the control group (P = 0.07, P = 0.64, P = 0.17, and P = 0.44 respectively). Although previous studies have shown significant differences in NLR and PLR levels in other types of glaucoma, we did not find any significant difference in NTG subjects. Our early report may give insight into the differential diagnosis of NTG.

Molecular Biomarkers for Glaucoma

Purpose of review

This article summarizes the current studies on molecular biomarkers with potential implications in diagnosis, prognosis, and response to treatment in patients with glaucoma.

Recent findings

Important advances have occurred in the understanding of the pathogenesis of glaucomatous neurodegeneration. Protein biomarkers associated with inflammatory, neurodegenerative, and other molecular pathways have been described in glaucoma patients in tear film, aqueous fluid, vitreous fluid, and serum, however, we are still far from having a clear picture of the whole molecular network that relates to the disease and its implications in clinical use.

Summary

Although more studies are needed, current and emerging molecular biomarkers candidates in glaucoma may eventually transition into clinical use and contribute to outline the concept of precision medicine and precision health in glaucoma.

Tears and ocular surface disorders: Usefulness of biomarkers

INTRODUCTION

Corroborating data suggest that the analysis of tear fluid might represent an additional tool in the ophthalmological practice.

AREAS COVERED

The purpose of this review was to sum up the tear protein profiles in healthy and diseased ocular surface and to highlight biomarker usefulness in the early diagnosis as well as at follow-up. This analysis encompasses a deep examination of the protein profile expression under physiological and pathological conditions. Tear protein profile analysis will allow in the near future discriminating between different grades of inflammation, from acute trauma toward immune-, endocrine-, and nervous-related disorders of the ocular surface.

CONCLUDING REMARKS

The review provides an overview of old and recent findings about inflammatory mediators identified at the ocular surface, under physiological and pathological conditions. To date, the analysis of tear fluid represents a new additional approach for diagnosis and management of ocular surface diseases. Understanding the pathophysiological mechanism could also offer significant advantages to develop strategies addressed to better clarify some complex ocular surface disorders. To sum up, the possibility to provide selective biomarkers as a future target of specific diseases should be considered for supporting diagnosis and management of ocular surface diseases.

Contact-Lens Biosensors

Rapid diagnosis and screening of diseases have become increasingly important in predictive and preventive medicine as they improve patient treatment strategies and reduce cost as well as burden on our healthcare system. In this regard, wearable devices are emerging as effective and reliable point-of-care diagnostics that can allow users to monitor their health at home. These wrist-worn, head-mounted, smart-textile, or smart-patches devices can offer valuable information on the conditions of patients as a non-invasive form of monitoring. However, they are significantly limited in monitoring physiological signals and biomechanics, and, mostly, rely on the physical attributes. Recently, developed wearable devices utilize body fluids, such as sweat, saliva, or skin interstitial fluid, and electrochemical interactions to allow continuous physiological condition and disease monitoring for users. Among them, tear fluid has been widely utilized in the investigation of ocular diseases, diabetes, and even cancers, because of its easy accessibility, lower complexity, and minimal invasiveness. By determining the concentration change of analytes within the tear fluid, it would be possible to identify disease progression and allow patient-oriented therapies. Considering the emerging trend of tear-based biosensing technology, this review article aims to focus on an overview of the tear fluid as a detection medium for certain diseases, such as ocular disorders, diabetes, and cancer. In addition, the rise and application of minimally invasive detection and monitoring via integrated contact lens biosensors will also be addressed, in regards to their practicality and current developmental progress.

Tear biomarkers in latanoprost and bimatoprost treated eyes

Purpose

Prostaglandin analogues (PGA’s) are the mainstay and first line of treatment in current glaucoma practise. Though latanoprost and bimatoprost are the most commonly used PGA’s with minimal side effects at lower concentrations like bimaotoprost 0.01%, direct comparison of their cytokine/MMP profile in tears has not been evaluated earlier. The study intends to ascribe PGA to the upregulation of MMPs, Cytokines and Chemokines mediating varied pathways to result in side effects of the drugs.

Methods

Tear sample collection was done from outer canthus of 30 eyes of 30 patients (primary open angle glaucoma (n = 26 and n’ = 20), normal tension glaucoma (n = 4 and n’ = 10), in latanoprost (n) 0.005% and bimatoprost (n’) 0.01% group respectively, with a mean age of 62±10.5 years) on >6 months of PGA use using Tear flo^TM Schirmer filter strip. Tear samples from 30 eyes of 30 cataract patients without drug treatment were used as the control. Gelatinolytic activity of MMP-9 and MMP-2 were examined by substrate gelatine zymography MMP-1 and TIMP-1 concentrations from tears samples with PGAs were evaluated by ELISA while cytokine concentration in the eluted tears was evaluated using a convenient bioplex kit assay (Milliplex MAP kit, HCYTMAG-60K-PX41, Millipore, Massachusetts, United States). The mean duration of use of PGA in both groups did not differ significantly (median 1.3 years in bimatoprost and 1.1 years in latanoprost eyes, p = 0.6).

Results

The tear MMP-9 expression was higher in eyes receiving latanoprost while the MMP-2 expression was higher in eyes receiving bimatoprost with MMP1 protein levels being higher in the former. Latanoprost treated eyes had marginally elevated tear cytokines involved in tissue remodelling while bimatoprost eyes showed elevated cytokines regulating allergic pathways.

Conclusion

Differential cytokine and MMP expression indicates differential signalling pathways mediating different cellular effects (evident as clinical and side effects) with the two drugs which can be explored further.

Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio as Novel Biomarkers of Primary Open-Angle Glaucoma

PURPOSE

We aimed to assess the levels of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in patients with primary open-angle glaucoma (POAG) and to compare the NLR and PLR results of patients with POAG and ocular hypertension, as well as in healthy controls.

PATIENTS AND METHODS

Eighty-four patients with POAG, 94 patients with ocular hypertension, and 80 healthy subjects were enrolled in this retrospective study. Complete ophthalmological examination and complete blood count measurements were performed for all subjects.

RESULTS

There was a significant difference in the NLR (P=0.003) and PLR (P=0.049) between POAG and control groups. In addition, there was a correlation between pattern standard deviation and NLR in the POAG group. The receiver operating characteristics analysis revealed that the value of NLR to distinguish patients with POAG and controls was found to be 0.651. The best cutoff value was 2.1, with a sensitivity of 65% and a specificity of 65%.

CONCLUSIONS

Our study for the first time provides evidence that NLR and PLR may be useful as biomarkers in patients with POAG.

Cytokine and chemokine tear levels in patients with uveitis

PURPOSE

To determine whether the levels of cytokines and chemokines in tears differ in uveitis patients and healthy subjects.

METHODS

Ninety-two uveitis patients (mean age 46.4 years) and 157 control healthy subjects (mean age 49.5 years) were recruited. Subjects with ocular surface diseases such as dry eye were excluded from the study. Using multiplex bead-based assays, tears (4 μl) were analysed for the concentration of interleukin (IL)-1β, IL-1RA, IL-2, IL-6, IL-7, IL-8/CXCL8, IL-10, IL-12p70, IL-15, IL-17A, IL-23, epidermal growth factor (EGF), fractalkine/CX3CL1, interferon-γ, IP-10/CXCL10, monocyte chemo-attractant protein (MCP)-1/CCL2, tumour necrosis factor-α, vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β1, TGF-β2 and TGF-β3. Tear molecule levels were compared between the groups and among the different forms of uveitis and disease severity.

RESULTS

Epidermal growth factor, IL-1RA, IL-7, IL-8/CXCL8, IP-10/CXCL10, MCP-1/CCL2, TGF-β2 and VEGF were detected in more than 75% of the samples in both groups. Statistically significant differences in percentage of detection between control and patient groups were found for IL-23, IL-1β, IL-15, EGF, fractalkine/CX3CL1 and MCP-1/CCL2. The concentrations of IL-1RA, IL-8/CXCL8, fractalkine/CX3CL1, IP-10/CXCL10, VEGF and TGF-β2 in uveitis tear samples were elevated compared to controls (p < 0.05). Significant differences in tear levels of those molecules and also EGF were also present depending on the anatomic classification of uveitis.

CONCLUSION

There were significant differences in the levels of several cytokines and chemokines in tears of patients with uveitis compared with healthy subjects. These results can help understand the underlying pathophysiology of the uveitis and could potentially aid in diagnosis.

Ocular surface evaluation in eyes with chronic glaucoma on long term topical antiglaucoma therapy

AIM

To evaluate ocular surface changes and its correlation with the central corneal subbasal nerve fibre layer in chronic glaucoma patients.

METHODS

A prospective comparative study of ocular surface evaluation was performed in 50 eyes of 25 patients using two or more antiglaucoma medications for at least 6mo and 50 eyes of 25 normal subjects without any ocular problems as controls. The study parameters evaluated included visual acuity, intraocular pressure, ocular surface evaluation parameters [fluorescein break-up time (FTBUT), Schirmer's I test, ocular surface staining scores and ocular surface disease index score (OSDI)], central corneal sensation (Cochet Bonnett aesthesiometer), central subbasal nerve fiber layer density (SBNFLD) by confocal microscopy.

RESULTS

The mean values in the glaucoma cases and control groups respectively were as follows: OSDI score (35.89±16.07/6.02±3.84; P=0.001), Schirmer's I test score (7.63±2.64 mm/12.86±1.93 mm; P=0.001), FTBUT (9.44±2.76s/11.8±1.88s; P=0.001), corneal (5.7±2.33/ 1.1±0.58; P=0.001) and conjunctival staining score (5.06±1.94/0.84±0.46; P=0.001), corneal sensitivity (4.68±0.44/5.07±0.37; P=0.076), mean subbasal nerve fiber number (3.58±0.99/5.40±1.70; P=0.001), SBNFL length (1101.44±287.56 µm/1963.70±562.56 µm; P=0.001) and density (6883.94±1798.03 µm/mm²/12 273.15±3516.04 µm/mm²; P=0.001). Dry eye severity of level 2 and 3 was seen in 66% of glaucoma group. Corneal (R²=0.86) and conjunctival staining (R²=0.71) and OSDI score (R²=0.67) showed statistically significant negative correlation with central corneal SBNFLD while FTBUT (R²=0.84), corneal sensitivity (R²=0.52) showed positive correlation to central corneal SBNFLD in the long term topical antiglaucoma medication group.

CONCLUSION

Ocular surface changes and antiglaucoma therapy induced dry eye is found to be associated with decreased SBNFLD in eyes on long term topical antiglaucoma medications.

Non-invasive objective and contemporary methods for measuring ocular surface inflammation in soft contact lens wearers - A review

Contact lens wear is one of the primary risk factors for the development of ocular surface inflammatory events. The purpose of this review is to examine and summarize existing knowledge on the mechanisms of contact lens related ocular surface inflammation and the evidence for the effectiveness of current objective methods to measure ocular surface inflammation. Contact lens wear is postulated to trigger an inflammatory response on the ocular surface due to mechanical, chemical, hypoxic stress, or by the introduction of microbes and their toxins. Apart from the traditional signs of inflammation, such as swelling, oedema, redness and heat, on the ocular surface, other methods to measure ocular surface inflammation in sub-clinical levels include tear inflammatory mediator concentrations, conjunctival cell morphology, and corneal epithelial dendritic cell density and morphology. Tear inflammatory mediator concentrations are up- or down-regulated during contact lens wear, with or without the presence of associated inflammatory events. There is higher conjunctival cell metaplasia observed with contact lens wear, but changes in goblet cell density are inconclusive. Dendritic cell density is seen to increase soon after initiating soft contact lens wear. The long term effects of contact lens wear on dendritic cell migration in the cornea and conjunctiva, including the lid wiper area, require further investigation. Currently patient factors, such as age, smoking, systemic diseases and genetic profile are being studied. A better understanding of these mechanisms may facilitate the development of new management options and strategies to minimize ocular surface inflammation related to contact lens wear.

Changes in Tear Cytokine Concentrations Following Discontinuation of Soft Contact Lenses-A Pilot Study

PURPOSE

This study investigated changes in selected tear cytokine concentrations (IL-1β, IL-1Ra, IL-6, IL-10, IL-12 (p70), and TNF-α) after a 1-week washout from soft contact lens wear (CLW), and the repeatability of cytokine measurements using custom multiplex assays.

METHODS

A total of 10 subjects completed this 6-visit (immediately following contact lens removal, and after 1, 2, 3, 4, and 7 [±1] days without CLW) pilot study. Approximately 20 to 30 μL of pooled basal tears were collected from both eyes at each visit. Two custom multiplex assays were used by two operators to quantify the concentration of tear cytokines. Tear samples from subjects 1 to 6 were analyzed using the first kit by operator 1. Tear samples from subject 7 to 10 plus additional tear samples from subjects 1 to 5, which were used to determine the between-kit per operator repeatability, were analyzed using the second kit by operator 2. Linear mixed models were used to determine changes in tear cytokine concentrations over time. Between-kit per operator and within-kit per operator repeatabilities were assessed using the Bland and Altman analysis.

RESULTS

There were no significant changes in tear cytokine concentrations over a 1-week washout of CLW. More than 99% of the tear samples had detectable levels of cytokines using custom multiplex assays. Within-kit per operator repeatability was good, but between-kit per operator repeatability was poor; likely due to protein degradation, differences in operator experience, and operating procedures.

CONCLUSION

A washout period may not be necessary when evaluating changes in tear cytokines with new contact lenses or lens care products. A well-trained operator using standardized operating procedures can produce repeatable measurements using custom multiplex assays.

The potential impact of recent insights into proteomic changes associated with glaucoma

INTRODUCTION

Glaucoma, a major ocular neuropathy, is still far from being understood on a molecular scale. Proteomic workflows revealed glaucoma associated alterations in different eye components. By using state-of-the-art mass spectrometric (MS) based discovery approaches large proteome datasets providing important information about glaucoma related proteins and pathways could be generated. Corresponding proteomic information could be retrieved from various ocular sample species derived from glaucoma experimental models or from original human material (e.g. optic nerve head or aqueous humor). However, particular eye tissues with the potential for understanding the disease's molecular pathomechanism remains underrepresented. Areas covered: The present review provides an overview of the analysis depth achieved for the glaucomatous eye proteome. With respect to different eye regions and biofluids, proteomics related literature was found using PubMed, Scholar and UniProtKB. Thereby, the review explores the potential of clinical proteomics for glaucoma research. Expert commentary: Proteomics will provide important contributions to understanding the molecular processes associated with glaucoma. Sensitive discovery and targeted MS approaches will assist understanding of the molecular interplay of different eye components and biofluids in glaucoma. Proteomic results will drive the comprehension of glaucoma, allowing a more stringent disease hypothesis within the coming years.

Cytokine biomarkers in tear film for primary open-angle glaucoma

Purpose

To determine the utility of tear film cytokines as biomarkers for early primary open-angle glaucoma (POAG).

Methods

Patients without POAG and eye drop-naïve patients with newly diagnosed POAG were recruited from an academic hospital-based glaucoma practice. Tear films of recruited patients were obtained and analyzed using a multiplex, high-sensitivity electrochemiluminescent enzyme-linked immunosorbent assay for proinflammatory cytokines (IFNγ, IL-10, IL-12p70, IL-13, IL-1β, IL-2, IL-4, IL-6, IL-8, and TNFα).

Results

Mean concentrations of tear film cytokines were lower in the glaucoma group for 8 of 10 cytokines tested. IL-12p70 (3.94±2.19 pg/mL in control vs 2.31±1.156 pg/mL in POAG; P=0.035) was significantly lower in the tear film of patients with newly diagnosed POAG.

Conclusion

Proinflammatory cytokines were lower in eye drop-naïve newly diagnosed glaucoma patients. Tear film cytokine profiles may be used as biomarkers of early POAG.

Bilateral choroidal effusion after selective laser trabeculoplasty

Selective laser trabeculoplasty (SLT) is an effective treatment to treat open-angle glaucoma with a low risk of complications. The case is presented of a 73 year-old woman with uncontrolled primary open-angle glaucoma who underwent selective laser trabeculoplasty in both eyes and developed bilateral choroidal effusion.

Latent Infections as a Risk Factor for Posttrabeculectomy Bleb Failure

PURPOSE

To investigate latent conjunctival Chlamydia trachomatis (CT) and Bacteroides fragilis (BF) infections as potential risk factors for posttrabeculectomy bleb failure.

PATIENTS AND METHODS

This retrospective observational study included 50 primary open-angle glaucoma eyes of 50 patients who were submitted to trabeculectomy without cytostatics from September 2010 to June 2011 and were followed up for at least a year. Preoperatively, conjunctival scrapings were taken and their specimens subjected to polymerase chain reaction, direct fluorescent assay and cell culture testing for CT, and culture for BF on blood agar medium. Serum CT-specific IgG and IgA and tear interleukin (IL)-1β and IL-8 concentrations were measured with enzyme-linked immunosorbent assay. We defined bleb failure as intraocular pressure >21 mm Hg with antiglaucoma medications, resulting from reduced bleb filtration capacity due to bleb fibrosis, fistula obstruction, flattened bleb, or encapsulated bleb, and no earlier than 2 weeks after surgery. At the time of the reintervention, a scleroconjunctival biopsy was obtained for histopathology (including direct fluorescent assay testing for CT). Eyes were divided into a failure group and a nonfailure group, depending on whether they developed bleb failure (required reintervention) or not within a follow-up year.

RESULTS

In the failure group (n=18), the frequencies of detection of CT and BF in conjunctival specimens were 27.8% and 66.7%, respectively, versus 0% and 9.4% in the nonfailure group (n=32). CT and BF were detected in 11.1% and 11.1%, respectively, of scleroconjunctival biopsies. IgG and IgA seropositivity to CT was found in 66.7% and 33.3%, respectively, of the failure group patients, versus 9.4% and 0% of the nonfailure group patients. Tear IL-1β and IL-8 levels were markedly elevated in the failure group (468.83±80.43 and 107.89±15.11 pg/mL, respectively) versus the nonfailure group (22.34±5.43 and 9.34±2.83 pg/mL, respectively).

CONCLUSION

Being a contributor to low-grade conjunctival inflammation, latent conjunctival CT, and BF infections in primary open-angle glaucoma patients represent risk factors for posttrabeculectomy bleb failure.

Chemokine (C-C motif) ligand 2 and chemokine (C-C motif) ligand 7 in angle-closure glaucoma

PURPOSE

To compare the concentrations of chemokine (C-C motif) ligand 2 (CCL2) and chemokine (C-C motif) ligand 7 (CCL7) in aqueous humour of eyes with acute primary angle-closure (APAC), primary angle-closure glaucoma (PACG) or with age-related cataract.

METHODS

The prospective investigation included a study group of 56 patients (24 patients with APAC; 32 patients with PACG) undergoing glaucoma surgery and a control group of 21 patients undergoing routine cataract surgery. The interval between glaucoma attack and trabeculectomy was 19.4 ± 9.8 days.

RESULTS

The concentrations of CCL2 (3037 ± 501 versus 1127 ± 141 pg/ml; p = 0.003) and CCL7 (10.5 ± 2.4 versus 2.8 ± 0.4 pg/ml; p < 0.001) were significantly higher in the APAC group than in the PACG group, while the concentrations of both cytokines did not differ significantly between the PACG group and the control group (CCL2: 1190 ± 98 pg/ml; p = 0.10; CCL7: 2.0 ± 0.6; p = 0.18). The concentrations of both cytokines were significantly and inversely correlated with the interval between the acute angle-closure attack and surgery (CCL2: p = 0.02; ρ = -0.48; CCL7: p = 0.04; ρ = -0.42). Higher CCL2 concentrations were associated with higher prevalence of surgical failure (28.6% versus 7.1%; p = 0.036).

CONCLUSIONS

Concentrations of CCL2 and CCL7 as major inflammatory cytokines with potential influence on the risk of filtering surgery failure were significantly elevated after an acute glaucoma attack and decreased with longer interval to the attack. Trabeculectomy may have a lower risk of failure if performed later than earlier after an acute glaucoma attack, with lower CCL2 concentrations associated with better surgical outcome.

Latanoprost-induced Cytokine and Chemokine Release From Human Tenon's Capsule Fibroblasts: Role of MAPK and NF-κB Signaling Pathways

PURPOSE

Long-term topical antiglaucoma therapy is considered a significant risk factor for failure of trabeculectomy. We investigated the effects of antiglaucoma drugs on proinflammatory cytokine and chemokine release from cultured human Tenon's capsule fibroblasts (HTFs) as well as the signaling pathways that underlie such effects.

MATERIALS AND METHODS

Release of the proinflammatory cytokine interleukin (IL)-6 and the chemokines IL-8 and monocyte chemotactic protein (MCP)-1 was measured with enzyme-linked immunosorbent assays. The phosphorylation (activation) of mitogen-activated protein kinases (MAPKs) as well as the phosphorylation and degradation of the nuclear factor-κB (NF-κB) inhibitor IκB-α were assessed by immunoblot analysis.

RESULTS

Latanoprost stimulated the release of IL-6, IL-8, and MCP-1 from HTFs in a concentration-dependent and time-dependent manner, whereas timolol maleate and pilocarpine had no such effects. Latanoprost also activated the MAPKs extracellular signal-regulated kinase, p38, and c-Jun NH2-terminal kinase as well as induced the phosphorylation and degradation of IκB-α in these cells. The latanoprost-induced release of IL-6, IL-8, and MCP-1 was attenuated by inhibitors of MAPK (PD98059, SB203580, or JNK inhibitor II) or NF-κB (IκB kinase 2 inhibitor) signaling pathways.

CONCLUSIONS

Latanoprost induced proinflammatory cytokine and chemokine release from HTFs in a manner dependent on MAPK and NF-κB signaling. These effects of latanoprost might influence bleb scarring after filtration surgery.