Current understanding of genetics and epigenetics in pseudoexfoliation syndrome and glaucoma.

Pseudoexfoliation is a complex, progressive, and systemic age-related disorder. The early stage of deposition of extracellular fibrillar material on ocular and extraocular tissues is termed as pseudoexfoliation syndrome (PEXS). The severe advanced stage is known as pseudoexfoliation glaucoma (PEXG), which involves increased intraocular pressure and optic nerve damage. Through genome-wide association and candidate gene studies, PEX has been associated with numerous genetic risk variants in various gene loci. However, the genetic basis of the disease fails to explain certain features of PEX pathology, such as the progressive nature of the disease, asymmetric ocular manifestation, age-related onset, and only a subset of PEXS individuals developing PEXG. Increasing evidence shows an interplay of genetic and epigenetic factors in the pathology of complex, multifactorial diseases. In this review, we have discussed the genetic basis of the disease and the emerging contribution of epigenetic regulations in PEX pathogenesis, focusing on DNA methylation and non-coding RNAs. Aberrant methylation patterns, histone modifications, and post-transcriptional regulation by microRNAs lead to aberrant gene expression changes. We have reviewed these aberrant epigenetic changes in PEX pathology and their effect on molecular pathways associated with PEX. We have further discussed some possible genetic/epigenetic-based diagnoses and therapeutics for PEX. Although studies to understand the role of epigenetic regulations in PEX are just emerging, epigenetic modifications contribute significantly to PEX pathogenesis and may pave the way for better and targeted therapeutics.

Role of clusterin gene 3'-UTR polymorphisms and promoter hypomethylation in the pathogenesis of pseudoexfoliation syndrome and pseudoexfoliation glaucoma.

Pseudoexfoliation (PEX) is a multifactorial age-related disease characterized by the deposition of extracellular fibrillar aggregates in the anterior ocular tissues. This study aims to identify the genetic and epigenetic contribution of clusterin (CLU) in PEX pathology. CLU is a molecular chaperone upregulated in PEX and genetically associated with the disease. Sequencing of a 2.9 kb region encompassing the previously associated rs2279590 in 250 control and 313 PEX [(207 pseudoexfoliation syndrome (PEXS) and 106 pseudoexfoliation glaucoma (PEXG)] individuals identified three single nucleotide polymorphisms (SNPs), rs9331942, rs9331949 and rs9331950, in the 3'-UTR of CLU of which rs9331942 and rs9331949 were found to be significantly associated with PEXS and PEXG as risk factors. Following in silico analysis, in vitro luciferase reporter assays in human embryonic kidney cells revealed that risk alleles at rs9331942 and rs9331949 bind to miR-223 and miR-1283, respectively, suggesting differential regulation of clusterin in the presence of risk alleles at the SNPs. Further, through bisulfite sequencing, we also identified that CLU promoter is hypomethylated in DNA from blood and lens capsules of PEX patients compared to controls that correlated with decreased expression of DNA methyltransferase 1 (DNMT1). Promoter demethylation of CLU using DNMT inhibitor, 5'-aza-dC, in human lens epithelial cells increased CLU expression. Chromatin immunoprecipitation assays showed that the demethylated CLU promoter provides increased access to the transcription factor, Sp1, which might lead to enhanced expression of CLU. In conclusion, this study highlights the different molecular mechanisms of clusterin regulation in pseudoexfoliation pathology.

The Importance of MicroRNA Expression in Pseudoexfoliation Syndrome.

Pseudoexfoliation syndrome (PEX) is an important systemic disorder of the extracellular matrix, in which granular amyloid-like protein fibers accumulate in the anterior segment of the eyeball as well as in other organs. PEX is currently considered to be a multifactorial systemic disorder with genetic and environmental risk factors. The aim of this manuscript was to analyze miR expression in PEX. In recent years, an attempt has been made to investigate and describe the level of expression of selected miRs in PEX. Four polymorphisms of genes isolated from the blood that may be related to PEX were identified and miR-122-5p was found to be upregulated in patient blood. Furthermore, 18 miRs were identified with a statistically different expression in the aqueous humor. A significantly elevated expression of miR-125b was found in the anterior lens capsule, and four miRs were described, which may have a significant impact on the development of PEX. Regulatory miR molecules are gaining more and more importance in research aimed at identifying and isolating molecular markers related to the pathogenesis and prognosis of PEX, but further studies are needed.

Towards preventing exfoliation glaucoma by targeting and removing fibrillar aggregates associated with exfoliation syndrome.

Exfoliation syndrome presents as an accumulation of insoluble fibrillar aggregates that commonly correlates with age and causes ocular complications, most notably open-angle glaucoma. Despite advances in understanding the pathogenesis and risk factors associated with exfoliation syndrome, there has been no significant progress in curative pharmacotherapy of this disease. It is thought that the ability to target the fibrillar aggregates associated with exfoliation may offer a new therapeutic approach, facilitating their direct removal from affected tissues. Phage display techniques yielded two peptides (LPSYNLHPHVPP, IPLLNPGSMQLS) that could differentiate between exfoliative and non-affected regions of the human lens capsule. These peptides were conjugated to magnetic particles using click chemistry to investigate their ability in targeting and removing exfoliation materials from the anterior human lens capsule. The behavior of the fibrillar materials upon binding to these magnetic particles was assessed using magnetic pins and rotating magnetic fields of various strengths. Ex vivo studies showed that the magnetic particle-peptide conjugates could generate enough mechanical force to remove large aggregates of exfoliation materials from the lens capsule when exposed to a low-frequency rotating magnetic field (5000 G, 20 Hz). Biocompatibility of targeting peptides with and without conjugated magnetic particles was confirmed using MTT cell toxicity assay, live/dead cell viability assay, and DNA fragmentation studies on primary cultured human trabecular meshwork cells. This is a novel, minimally invasive, therapeutic approach for the treatment of exfoliation glaucoma via the targeting and removal of exfoliation materials that could be applied to all tissues within the anterior segment of the eye.

Quantitative analysis of exosomes in the aqueous humor of Korean patients with pseudoexfoliation glaucoma.

We aimed to quantitatively analyze the exosome and its cargo in individual aqueous humor (AH) samples from pseudoexfoliation (PEX) glaucoma patients compared to controls using a novel detection platform. We investigated the size distribution and measured the quantitative exosome particle counts in each AH sample. AH (80-120 µL) was obtained during cataract surgery or glaucoma filtering surgery from 12 Korean subjects (six with PEX glaucoma and six age-matched controls). The mean size of the exosomes was 58.9 ± 18.5 nm measured by a tangential flow filtration system using single-particle interferometric reflectance imaging sensor. Exosome particle count in each CD 63, CD 81, and CD9 spot was significantly greater in PEX glaucoma than in controls in total, CD 63, CD9, syntenin, and scattering(all p < 0.003). The CD63 spot showed a particle count of 8319.1 ± 797.7 in PEX glaucoma patients and 4786.8 ± 1302.1 in controls (p = 1.88E-11). Individual fluorescent capture spot images also revealed denser exosome particles in PEX patients than in controls. Syntenin, indicating exosomal origin, was detected in all AH samples. Exosomes differentially detected in AH suggest the possible role of exosomes in the pathogenesis of PEX glaucoma.

Dysregulated Retinoic Acid Signaling in the Pathogenesis of Pseudoexfoliation Syndrome.

Pseudoexfoliation (PEX) syndrome, a stress-induced fibrotic matrix process, is the most common recognizable cause of open-angle glaucoma worldwide. The recent identification of PEX-associated gene variants uncovered the vitamin A metabolic pathway as a factor influencing the risk of disease. In this study, we analyzed the role of the retinoic acid (RA) signaling pathway in the PEX-associated matrix metabolism and evaluated its targeting as a potential candidate for an anti-fibrotic intervention. We provided evidence that decreased expression levels of RA pathway components and diminished RA signaling activity occur in an antagonistic crosstalk with TGF-ß1/Smad signaling in ocular tissues and cells from PEX patients when compared with age-matched controls. Genetic and pharmacologic modes of RA pathway inhibition induced the expression and production of PEX-associated matrix components by disease-relevant cell culture models in vitro. Conversely, RA signaling pathway activation by natural and synthetic retinoids was able to suppress PEX-associated matrix production and formation of microfibrillar networks via antagonization of Smad-dependent TGF-ß1 signaling. The findings indicate that deficient RA signaling in conjunction with hyperactivated TGF-ß1/Smad signaling is a driver of PEX-associated fibrosis, and that restoration of RA signaling may be a promising strategy for anti-fibrotic intervention in patients with PEX syndrome and glaucoma.

MicroRNA Expression in Pseudoexfoliation Syndrome with the Use of Next-Generation Sequencing.

Pseudoexfoliation syndrome (PEX) is a clinically important and biologically intriguing systemic disorder of the extracellular matrix. PEX etiopathogenesis was proved to be connected to multiple genes and other factors. However, the exact etiopathogenesis remains unknown. The aim of this study was to analyze miR expression in PEX using next-generation sequencing. An attempt was made to find the most commonly occurring miR in PEX, to evaluate miR that may have an essential role in the etiology of PEX syndrome. In addition, the correlation between the selected miRs' expressions and age was investigated. Anterior lens capsules were obtained during cataract surgery. Next-generation sequencing was conducted on Illumina MiSeq. The average age was 68.2 years (with standard deviation +/- 6.92 years). Ten miRs with the highest level of expression represent approx. 95% of all readings. Four miRs with statistically significant differences in expression between groups have been distinguished: miR-671-3p, miR374a-5p, miR-1307-5p and miR-708-5p. The relationship between the most frequent miRs' expressions and age has been evaluated and no correlation has been detected. In view of the above, it seems reasonable to examine the influence of miR on the biogenesis of PEX. Further studies on miR-671-3p, miR-374a-5p, miR-1307-5p and miR-708-5p expression in PEX are needed.

RNA Sequencing of Lens Capsular Epithelium Implicates Novel Pathways in Pseudoexfoliation Syndrome.

Purpose: Pseudoexfoliation syndrome (PEX) is a common systemic disease that results in severe and often irreversible vision loss. Despite considerable research effort, PEX remains incompletely understood. This study sought to perform the first RNAseq study in elucidate the pathophysiology of PEX, and contribute a publicly available transcriptomic data resource for future research. Methods: Human ocular lens capsular epithelium samples were collected from 25 patients with PEX and 39 non-PEX controls undergoing cataract surgery. RNA extracted from these specimens was subjected to polyadenylated (mRNA) selection and deep bulk RNA sequencing. Differential expression analysis investigated protein-coding gene transcripts. Exploratory analyses used pathway analysis tools, and curated class- and disease-specific gene sets. Results: Differential expression analysis demonstrated that 2882 genes were differentially expressed according to PEX status. Genes associated with viral gene expression pathways were among the most upregulated, alongside genes encoding ribosomal and mitochondrial respiratory transport chain proteins. Cell adhesion protein transcripts including type 4 collagen subunits were downregulated. Conclusions: This comparative transcriptomic dataset highlights novel and previously recognized pathogenic pathways in PEX and provides the first comprehensive transcriptomic resource, adding an additional layer to build further understanding of PEX pathophysiology.

Primary Human Trabecular Meshwork Model for Pseudoexfoliation.

The lack of an animal model or an in vitro model limits experimental options for studying temporal molecular events in pseudoexfoliation syndrome (PXF), an age related fibrillopathy causing trabecular meshwork damage and glaucoma. Our goal was to create a workable in vitro model of PXF using primary human TM (HTM) cell lines simulating human disease. Primary HTM cells harvested from healthy donors (n = 3), were exposed to various concentrations (5 ng/mL, 10 ng/mL, 15 ng/mL) of transforming growth factor-beta1 (TGF-ß1) for different time points. Morphological change of epithelial-mesenchymal transition (EMT) was analyzed by direct microscopic visualization and immunoblotting for EMT markers. Expression of pro-fibrotic markers were analyzed by quantitative RT-PCR and immunoblotting. Cell viability and death in treated cells was analyzed using FACS and MTT assay. Protein complex and amyloid aggregate formation was analyzed by Immunofluorescence of oligomer11 and amyloid beta fibrils. Effect of these changes with pharmacological inhibitors of canonical and non-canonical TGF pathway was done to analyze the pathway involved. The expression of pro-fibrotic markers was markedly upregulated at 10 ng/mL of TGF-ß1 exposure at 48-72 h of exposure with associated EMT changes at the same time point. Protein aggregates were seen maximally at these time points that were found to be localized around the nucleus and in the extracellular matrix (ECM). EMT and pro-fibrotic expression was differentially regulated by different canonical and non-canonical pathways suggesting complex regulatory mechanisms. This in vitro model using HTM cells simulated the main characteristics of human disease in PXF like pro-fibrotic gene expression, EMT, and aggregate formation.

The effects of trypan blue use on the corneal endothelium during cataract surgery in patients with pseudoexfoliation syndrome (PEX).

PURPOSE: In the present clinical study, it was aimed to investigate the possible effects of Trypan blue (TB) use on the corneal endothelium during cataract surgery in eyes with pseudoexfoliation syndrome (PEX) during a three-month follow-up period using the contralateral eye control design. METHODS: This prospective, randomised controlled, individual cohort study included 92 eyes of 46 patients with bilateral PEX and cataracts. While 1% TB was applied to one eye of the patients before capsulorhexis (study group), it was not applied to the other eye (control group). Both groups were compared preoperatively and postoperatively in terms of endothelial cell density (ECD), endothelial cell loss (%), pleomorphism, polymegathism and central corneal thickness (CCT) using specular microscopy. RESULTS: Preoperative corneal ECD was measured as 2362.56 ± 253.27 in the study group, 2380.84 ± 220.54 in the control group, and 2145.58 ± 221.71 in the study group and 2184.97 ± 200.94 cells/mm2 in the control group in the postoperative 3rd-month follow-up (p = 0.71 and = 0.37, respectively). In addition, there were no significant differences between the two groups in terms of the percentage of hexagonal cells, coefficient of variation (CV), and CCT both preoperatively and postoperatively 3 months later (p = 0.78, =0.39, =0.95 preoperatively and p = 0.31, =0.26, =0.83 postoperatively, respectively). CONCLUSION: This study demonstrated that the injection of 1% TB into the anterior chamber for staining the anterior capsule during cataract surgery did not cause significant corneal endothelial changes at postoperative 3rd months, despite the increased fragility of corneal endothelial cells in patients with PEX.

Pseudoexfoliation syndrome in diabetic patients: transmission electron microscopy study of anterior lens epithelial cells.

Purpose: to examine the lens epithelial cells in diabetic patients with pseudoexfoliation to ultramicroscope and to compare the findings with those of patients without diabetes mellitus (DM) and/or without pseudoexfoliation (PEX). Materials and Methods: Forty patients aged 65-86 years were enrolled in the study. All patients had senile cataract and were divided into four groups of ten patients in each group. Group I: patients without pseudoexfoliation, without DM, Group II: without pseudoexfoliation, with DM, Group III: with pseudoexfoliation, without DM, Group IV (Pseudoexfoliation-Diabetic Group): with pseudoexfoliation, with DM. In all cases, part of the central portion of anterior lens capsule was removed during routine cataract surgery, and was properly prepared in order to be examined under a transmission electron microscope. Results: In the control group, mainly degenerative alterations to varying extents were observed. In all groups, intracellular and extracellular oedema, multilayering, apoptosis, completely destroyed cells adjacent to normal cellswere described. In the diabetic group, alterations were more severe with respect to group I. In PEX cases, the additionalirregularity of the epithelium surface, loose intercellular connection, as well as the loose connection between cells and basement membrane were described with the presence of PEX material free and within the basement membrane. In cases with PEX and DM, degenerative alterations and PEX material were observed as well, but the epithelium was better conserved compared to the PEX group. Conclusion: the observed lesions were more extended and more frequent in the pseudoexfoliation group, followed by the diabetic group. The pseudoexfoliation-diabetic group presented less intense modifications raising questions about the interaction of these different diseases. Abbreviations: DM = Diabetes Mellitus, PEX = Pseudoexfoliation, PXM = Pseudoexfoliative Material, AD = Alzheimer disease, TGF-ß1 = Transforming Growth Factor beta 1, WHO = World Health Organization, LEC = Lens Epithelium Cells, BM = Basement Membrane, CM = Cytoplasmic Membrane.

TGFß1, MMPs and cytokines profiles in ocular surface: Possible tear biomarkers for pseudoexfoliation.

PURPOSE: Pseudoexfoliation (PXF) is a unique form of glaucoma characterized by accumulation of exfoliative material in the eyes. Changes in tear profile in disease stages may give us insights into molecular mechanisms involved in causing glaucoma in the eye. METHODS: All patients were categorized into three main categories; pseudoexfoliation (PXF), pseudoexfoliation glaucoma (PXG) and cataract, which served as control. Cytokines, transforming growth factor ß1 (TGFß1), matrix metalloproteases (MMPs) and fibronectin (FN1) were assessed with multiplex bead assay, enzyme-linked immunosorbent assay (ELISA), gelatin zymography, and immunohistochemistry (IHC) respectively in different ocular tissues such as tears, tenon's capsule, aqueous humor (AH) and serum samples of patients with PXF stages. RESULTS: We found that TGFß1, MMP-9 and FN1 protein expression were upregulated in tears, tenon's capsule and AH samples in PXG compared to PXF, though the MMP-9 protein activity was downregulated in PXG compared with control or PXF. We have also found that in PXG tears sample the fold change of TGF-α (Transforming Growth Factor-α), MDC (Macrophage Derived Chemokine), IL-8 (Interleukin-8), VEGF (Vascular Endothelial Growth Factor) were significantly downregulated and the levels of GM-CSF (Granulocyte Macrophage Colony Stimulating Factor), IP-10 (Interferon- γ produced protein-10) were significant upregulated. While in AH; IL-6 (Interleukin-6), IL-8, VEGF, IFN-a2 (Interferon- α2), GRO (Growth regulated alpha protein) levels were found lower and IL1a (Interleukin-1α) level was higher in PXG compared to PXF. And in serum; IFN-a2, Eotaxin, GM-CSF, Fractalkine, IL-10 (Interleukin-10), IL1Ra (Interleukin-1 receptor antagonist), IL-7 (Interleukin-7), IL-8, MIP1ß (Macrophage Inflammatory Protein-1ß), MCP-1 (Monocyte Chemoattractant Protein-1) levels were significantly upregulated and PDGF-AA (Platelet Derived Growth Factor-AA) level was downregulated in the patients with PXG compared to PXF. CONCLUSIONS: Altered expression of these molecules in tears may therefore be used as a signal for onset of glaucoma or for identifying eyes at risk of developing glaucoma in PXF.

Comparison of Peripapillary Choroidal Microvasculature Dropout in Primary Open-angle, Primary Angle-closure, and Pseudoexfoliation Glaucoma.

PRECIS: The prevalence of choroidal microvascular dropout (CMvD) was significantly higher in primary open-angle glaucoma (POAG) than primary angle-closure glaucoma (PACG) or pseudoexfoliation glaucoma (PXG) in the early stage. However, in the advanced stage, it did not differ among the 3 groups. PURPOSE: The purpose of this study was to compare the prevalence of peripapillary CMvD in POAG, PACG, and PXG. MATERIALS AND METHODS: The presence of peripapillary CMvD was identified using optical coherence tomography angiography (AngioVue/RTVue-XR) imaging of the choroid in 186 eyes from 186 subjects [age and visual field (VF) mean deviation (MD) matched; 62 POAG, 62 PACG, and 62 PXG eyes]. Prevalence of CMvD was compared among glaucoma types in early and moderate to advanced disease, as divided by VF MD (-6 dB). The association between glaucoma type and presence of CMvD was evaluated using logistic regression analysis. RESULTS: Prevalence of CMvD was significantly different between glaucoma types in early-stage disease (PACG 7.5%, PXG 25%, and POAG 46.3%, P<0.001), but it did not differ between glaucoma types in eyes with moderate to advanced disease (PACG 59.1%, PXG 68.2%, and POAG 81%; P=0.331). After adjusting for age, sex, the ß-zone peripapillary atrophy/disc ratio, and glaucoma severity (VF MD), the CMvD odds ratio was 7.50 times greater in POAG than in PACG (P=0.001). CONCLUSIONS: CMvD was more common in POAG relative to both PACG and PXG, especially in early-stage disease. This finding suggested a role for ischemic injury in the pathogenesis of POAG.

Risk Factors for Corneal Endothelial Cell Loss in Patients with Pseudoexfoliation Syndrome.

This study investigated corneal endothelial cell density (ECD) in pseudoexfoliation (PEX) syndrome patients and evaluated the clinical factors associated with ECD for 51 eyes of 41 phakic patients with pseudoexfoliation (PEX group) and 201 eyes of 117 patients with age-related cataracts (control group) as an age-matched control to the PEX group. Variable clinical factors, including ECD, central corneal thickness (CCT), anterior chamber depth (ACD), number of anti-glaucoma eye drops and severity of PEX, were examined using multivariate analyses. Severity of PEX was as follows: Mild in 28 eyes, Moderate in 16 eyes, and Severe in 7 eyes. The mean ECD was 2,548 ± 409 cells/mm2 in the PEX group and 2,757 ± 282 cells/mm2 in the control group, respectively, and ECD in the PEX group was significantly lower than that in the control group (P = 0.02). Multivariate analyses revealed that the severity of PEX [-176.8, 95% confidence interval (CI) (-244.5, -109.2), P < 0.01] was significantly associated with lower ECD. Accumulation of PEX materials contributed to early corneal endothelial decompensation.

Epigenetic silencing of heat shock protein 70 through DNA hypermethylation in pseudoexfoliation syndrome and glaucoma.

This study is intended to investigate the epigenetic regulation of the most conserved molecular chaperone, HSP70 and its potential role in the pathophysiology of pseudoexfoliation syndrome (PEXS) and glaucoma (PEXG), a protein aggregopathy, contributing significantly to world blindness. Expression levels of HSP70 were significantly decreased in the lens capsule (LC) of PEXS but not in PEXG compared with that in control. Bisulfite sequencing of the LC of the study subjects revealed that the CpG islands (CGIs) located in the exonic region but not in the promoter region of HSP70 displayed hypermethylation only in PEXS individuals. There was a corresponding increase in DNA methyltransferase 3A (DNMT3A) expression in only PEXS individuals suggesting de novo methylation in this stage of the disease condition. On the other hand, peripheral blood of both PEXS and PEXG cases showed hypermethylation in the exonic region when compared with non-PEX controls displaying tissue-specific effects. Further, functional analyses of CGI spanning the exon revealed a decreased gene expression in the presence of methylated in comparison with unmethylated reporter gene vectors. Treatment of human lens epithelial B-3 (HLE B-3) cells with DNMT inhibitor restored the expression of HSP70 following depletion in methylation level at exonic CpG sites. In conclusion, a decreased HSP70 expression correlates with hypermethylation of a CGI of HSP70 in PEXS individuals. The present findings enhance our current understanding of the mechanism underlying HSP70 repression, contributing to the pathogenesis of PEX.

Association of IL-10 gene promoter polymorphisms with susceptibility to pseudoexfoliation syndrome, pseudoexfoliative and primary open-angle glaucoma.

BACKGROUND: The involvement of cytokines in pathogenesis of pseudoexfoliation syndrome and glaucoma has been demonstrated in several studies. The aim of the present study was to explore the association between three promoter polymorphisms -592C/A (rs1800872), - 819C/T (rs1800871) and -1082A/G (rs1800896) of interleukin 10 (IL-10) gene with susceptibility to pseudoexfoliation syndrome (PEX), pseudoexfoliative glaucoma (PEXG), and primary open-angle glaucoma (POAG). METHODS: In this study, 114 PEX, 118 PEXG, 114 POAG patients and 126 healthy individuals from Iranian population were participated. Detailed ophthalmic examinations by an ophthalmologist including slit-lamp bio-microscopic examination, dilated examination of the lens, gonioscopy, and funduscopy were carried out on patients and controls. Genomic DNA was extracted from the blood samples and ARMS-PCR was performed to detect promoter polymorphisms of IL-10. RESULTS: In all three SNPs studied, there was a significant difference in the genotype distribution between patients and control subjects. Results revealed that the AA genotype of IL-10 -592C/A SNP is associated with PEX. However, TT genotype of -819C/T and AA genotype of -1082A/G SNP are significantly associated with susceptibility to either PEX or PEXG and POAG disorders. Furthermore, the ACC haplotype containing the IL-10 -1082A allele was associated with PEX (P = 0.02, OR = 5.76, 95% CI = 5.17-24.49), PEXG (P = 0.006, OR = 7.54, 95% CI = 6.62-30.76) and POAG (P = 0.003, OR = 8.11, 95% CI = 7.13-33.15). CONCLUSIONS: Our results demonstrated that IL-10 gene promoter polymorphisms are associated with susceptibility to PEX, PEXG and POAG in Iranian population. Considering the fact that IL-10 polymorphisms are associated with various IL-10 expressions, further research is needed to explain its involvement in these disorders and the formation of extracellular fibrillar amyloid deposits in PEX and PEXG.

Identification and activity of the functional complex between hnRNPL and the pseudoexfoliation syndrome-associated lncRNA, LOXL1-AS1.

Individuals with pseudoexfoliation (PEX) syndrome exhibit various connective tissue pathologies associated with dysregulated extracellular matrix homeostasis. PEX glaucoma is a common, aggressive form of open-angle glaucoma resulting from the deposition of fibrillary material in the conventional outflow pathway. However, the molecular mechanisms that drive pathogenesis and genetic risk remain poorly understood. PEX glaucoma-associated single-nucleotide polymorphisms are located in and affect activity of the promoter of LOXL1-AS1, a long non-coding RNA (lncRNA). Nuclear and non-nuclear lncRNAs regulate a host of biological processes, and when dysregulated, contribute to disease. Here we report that LOXL1-AS1 localizes to the nucleus where it selectively binds to the mRNA processing protein, heterogeneous nuclear ribonucleoprotein-L (hnRNPL). Both components of this complex are critical for the regulation of global gene expression in ocular cells, making LOXL1-AS1 a prime target for investigation in PEX syndrome and glaucoma.

Corneal sublayer thickness in patients with pseudoexfoliation syndrome evaluated by anterior segment optical coherence tomography.

PURPOSE: The aim of the study was to evaluate the thickness of each corneal sublayer in patients with pseudoexfoliation syndrome (PXS). METHODS: The study's sample consisted of the 74 eyes of 74 patients with PXS (group 1) and the 80 eyes of 80 individuals without PXS (group 2). Each participant was performed anterior segment optical coherence tomography (AS-OCT) and Pentacam-Scheimpflug imaging. The thicknesses of corneal epithelium, Bowman's layer, stroma, and Descemet membrane-endothelial complex were measured separately from the AS-OCT images, on the central, 2 mm superior and inferior of the cornea. Central corneal thickness (CCT), apical corneal thickness (ACT), thinnest corneal thickness (TCT), and corneal volume were also evaluated. RESULTS: According to the measurements of corneal topography, in group 1 versus group 2, mean CCT (529.85 ± 32.33 µm vs 551.36 ± 39.12 µm, p < 0.001), mean ACT (532.21 ± 35.56 µm vs 552.26 ± 49.24 µm, p < 0.001), and mean TCT (527.54 ± 51.45 µm vs 546.20 ± 49.20 µm, p = 0.002) were significantly thinner in group 1. In AS-OCT, the thickness of the epithelium, stroma, and Descemet membrane-endothelial complex in the central, inferior, and superior cornea were significantly thinner in group 1 than in group 2. However, the thickness of Bowman's layer did not significantly differ between the groups. CONCLUSIONS: Our results indicate that all corneal sublayers except Bowman's layer were thinner in eyes with PXS than in healthy ones. Therefore, caution should be exercised for corneal involvement in patients with PXS.

Molecular Genetics of Glaucoma: Subtype and Ethnicity Considerations.

Glaucoma, the world's leading cause of irreversible blindness, is a complex disease, with differential presentation as well as ethnic and geographic disparities. The multifactorial nature of glaucoma complicates the study of genetics and genetic involvement in the disease process. This review synthesizes the current literature on glaucoma and genetics, as stratified by glaucoma subtype and ethnicity. Primary open-angle glaucoma (POAG) is the most common cause of glaucoma worldwide, with the only treatable risk factor (RF) being the reduction of intraocular pressure (IOP). Genes associated with elevated IOP or POAG risk include: ABCA1, AFAP1, ARHGEF12, ATXN2, CAV1, CDKN2B-AS1, FOXC1, GAS7, GMDS, SIX1/SIX6, TMCO1, and TXNRD2. However, there are variations in RF and genetic factors based on ethnic and geographic differences; it is clear that unified molecular pathways accounting for POAG pathogenesis remain uncertain, although inflammation and senescence likely play an important role. There are similar ethnic and geographic complexities in primary angle closure glaucoma (PACG), but several genes have been associated with this disorder, including MMP9, HGF, HSP70, MFRP, and eNOS. In exfoliation glaucoma (XFG), genes implicated include LOXL1, CACNA1A, POMP, TMEM136, AGPAT1, RBMS3, and SEMA6A. Despite tremendous progress, major gaps remain in resolving the genetic architecture for the various glaucoma subtypes across ancestries. Large scale carefully designed studies are required to advance understanding of genetic loci as RF in glaucoma pathophysiology and to improve diagnosis and treatment options.