Human Lens Research Articles

Towards the Identification and Characterization of Putative Adult Human Lens Epithelial Stem Cells.

The anterior lens epithelium has the ability to differentiate into lens fibres throughout its life. The present study aims to identify and functionally characterize the adult stem cells in the human lens epithelium. Whole mounts of lens epithelium from donor eyes (normal/cataract) were immunostained for SOX2, gap junction protein alpha 1 (GJA1), PAX6, α, β and γ-crystallins, followed by a confocal analysis. The functional property of adult stem cells was analysed by their sphere forming ability using cultured lens epithelial cells from different zones. Based on marker expression, the lens epithelium was divided into four zones: the central zone, characterized by a small population of PAX6+, GJA1-, β-crystallin- and γ-crystallin- cells; the germinative zone, characterized by PAX6+, GJA1+, β-crystallin- and γ-crystallin-; the transitional zone, characterized by PAX6+, GJA1+, β-crystallin+ and γ-crystallin-; and the equatorial zone, characterized by PAX6+/-, GJA1+, β-crystallin+, and γ-crystallin+ cells. The putative lens epithelial stem cells identified as SOX2+ and GJA1 membrane expression negative cells were located only in the central zone (1.89 ± 0.84%). Compared to the other zones, a significant percentage of spheres were identified in the central zone (1.68 ± 1.04%), consistent with the location of the putative adult lens epithelial stem cells. In the cataractous lens, an absence of SOX2 expression and a significant reduction in sphere forming ability (0.33 ± 0.11%) were observed in the central zone. The above findings confirmed the presence of putative stem cells in the central zone of the adult human lens epithelium and indicated their probable association with cataract development.

Digital Platforms and the Right to Just and Favorable Conditions of Work: A Business and Human Rights Perspective

Abstract Digital platform economy has radically changed the modes in which work is organized, stretching the functionality of legal environment of work and its governance. This article builds on a strand of labor law scholarship that advances the need to rethink the legal construction of work and work relationship in order to adapt it to the dynamically evolving socio-economic context. By applying a business and human rights lens to this process, this article confutes the mainstream argument that labor rights guarantees remain contingent on an individual’s enjoying the status of an employee under national jurisdiction. We survey a largely underexamined conception of affording protection to platform workers under International Human Rights Law (IHRL). In doing so, we argue that the instruments of IHRL may in some respects be even better placed than that of national law, both strengthening and complementing areas where state protection is weak or non-existent. Through the right to just and favorable conditions of work perspective, we outline the non-contested, albeit partly poorly implemented obligations of states, as well as largely contentious and contested responsibilities of private actors such as digital platforms towards the rights-holders. We conclude by arguing that the leverage offered by IHRL in the struggle to curb a quasi-sovereign power of the platform largely outweighs the democratically motivated objections this avenue may raise.

Transmittance characteristics of transparent hydrophobic acrylic foldable intraocular lenses that were in vivo for a prolonged period of time: A UV visible spectrophotometric study.

To record experimental data on the spectral transmittance characteristics of transparent hydrophobic acrylic foldable IOLs, which were in vivo for a prolonged period of time and explanted under clinical indications and also to compare the data with that of corresponding control and crystalline lens along with review of the relevant literature. Material and make of each of the explanted intraocular lenses (IOLs) as well as pre-explantation clinical status of the eyes were confirmed from the medical record. The transmittance of wavelength from 185 to 900 nm of each of the selected IOLs was measured using Shimadzu UV 2600 UV visible (UV-Vis) spectrophotometer in double-beam configuration and probe version 2.16 software. The data obtained were statistically analyzed. The mean transmittance of 12 clinically explanted IOLs at spectral range 300-700 nm was 49.5% ± SD 6.9%. This value was 10% and 38% less than the corresponding clear (59% ± SD 0.4%) and yellow (87.5% ± SD 0.4%) control, respectively. The mean transmittance of the analytes in the UV range was 43.3 ± SD 6.9%, and it was almost similar to the control. The data showed wide variations without good correlation, and it matches with the human crystalline lens at the age range of 50-60 years. All eyes were otherwise healthy, and none had age-related macular degeneration. In comparison with fresh IOL with a yellow filter, light transmittance at the spectral range 300-700 nm was found decreased in all the IOLs, which were in vivo for an average period of 12.25 ± 4.4 years. All IOLs transmitted variable amounts of UV radiation. More data are required for further analysis on the subject.

LensAge index as a deep learning-based biological age for self-monitoring the risks of age-related diseases and mortality

Age is closely related to human health and disease risks. However, chronologically defined age often disagrees with biological age, primarily due to genetic and environmental variables. Identifying effective indicators for biological age in clinical practice and self-monitoring is important but currently lacking. The human lens accumulates age-related changes that are amenable to rapid and objective assessment. Here, using lens photographs from 20 to 96-year-olds, we develop LensAge to reflect lens aging via deep learning. LensAge is closely correlated with chronological age of relatively healthy individuals (R2 > 0.80, mean absolute errors of 4.25 to 4.82 years). Among the general population, we calculate the LensAge index by contrasting LensAge and chronological age to reflect the aging rate relative to peers. The LensAge index effectively reveals the risks of age-related eye and systemic disease occurrence, as well as all-cause mortality. It outperforms chronological age in reflecting age-related disease risks (p < 0.001). More importantly, our models can conveniently work based on smartphone photographs, suggesting suitability for routine self-examination of aging status. Overall, our study demonstrates that the LensAge index may serve as an ideal quantitative indicator for clinically assessing and self-monitoring biological age in humans.

Using a human rights lens to understand and address loss and damage

Using a human rights lens to understand and address loss and damage

Topical ocular application of aggrelyte-2A reduces lens stiffness in mice.

Presbyopia is the progressive loss of the ability of the lens to focus on nearby objects due to its increased stiffness. It occurs in the mid-40s and continues to worsen until the mid-60s. The age-associated increase in protein cross-linking in the lens leads to protein aggregation and water insolubility, especially in the nuclear region, contributing to lens stiffness. This study reports the development of aggrelyte-2A (methyl S-acetyl-N-(3,3-dimethylbutanoyl) cysteinate, a derivative of our previously reported aggrelyte-2) for reversing the stiffness of aged lenses. Aggrelyte-2A showed minimal toxicity in cultured mouse lens epithelial cells (up to 2000 µM) and human lens epithelial cells (up to 250 µM). Lenses from aged mice (age: 24-25 months) treated with 1 mM aggrelyte-2A for 24h, and human lenses (age: 47-67 years) treated with 250 µM aggrelyte-2A for 48h showed 11-14% reductions in stiffness, accompanied by an increase in acetyllysine in lens proteins, and free-thiols in the lens. Topical application of aggrelyte-2A (40 mM, 5 µl twice daily for 4 weeks) on mouse eyes significantly reduced lens stiffness. The topical application showed no toxicity to the lens, cornea, or retina, as revealed by morphological examination, H&E staining, and optical coherence tomography. These data suggest that aggrelyte-2A could be developed as a presbyopia-reversing therapeutic.

Dehydroalanine and dehydrobutyrine in aging and cataractous lenses reveal site-specific consequences of spontaneous protein degradation.

Protein post-translational modifications (PTMs) have been associated with aging and age-related diseases. PTMs are particularly impactful in long-lived proteins, such as those found in the ocular lens, because they accumulate with age. Two PTMs that lead to protein-protein crosslinks in aged and cataractous lenses are dehydroalanine (DHA) and dehydrobutyrine (DHB); formed from cysteine/serine and threonine residues, respectively. The purpose of this study was to quantitate DHA and DHB in human lens proteins as a function of age and cataract status. Human lenses of various ages were divided into five donor groups: transparent lenses (18-22-year-old, 48-64-year-old, and 70-93-year-old) and cataractous human lenses of two age groups (48-64-year-old lenses, and 70-93-year-old lenses) and were subjected to proteomic analysis. Relative DHA and DHB peptide levels were quantified and compared to their non-modified peptide counterparts. For most lens proteins containing DHA or DHB, higher amounts of DHA- and DHB-modified peptides were detected in aged and cataractous lenses. DHA-containing peptides were classified into three groups based on abundance changes with age and cataract: those that (1) increased only in age-related nuclear cataract (ARNC), (2) increased in aged and cataractous lenses, and (3) decreased in aged lenses and ARNC. There was no indication that DHA or DHB levels were dependent on lens region. In most donor groups, proteins with DHA and DHB were more likely to be found among urea-insoluble proteins rather than among water- or urea-soluble proteins. DHA and DHB formation may induce structural effects that make proteins less soluble in water that leads to age-related protein insolubility and possibly aggregation and light scattering.

The right to life? How a human rights lens might prevent deaths in custody

The right to life? How a human rights lens might prevent deaths in custody

The Korean “Human Rights Lens in Social Work” Scale Equips Social Workers to Promote Human Rights in Social Service Settings

This study presents the validation of Korean version of the Human Rights Lens in Social Work (K-HRLSW) scale, a measure that can be used to foster the promotion of human rights in Korean social service settings. First, the English-language HRLSW was translated and adapted for Korean language and culture. Then, item analyses, exploratory factor analysis (EFA), and confirmatory factor analysis (CFA) were conducted to verify the psychometric properties of the Korean-language scale. For cross-validity, a total of 401 social workers were randomly split into two groups (group 1 = 202; group 2 = 199) to conduct EFA and CFA on separate samples. The overall reliability of the measure was good (alpha= .796), and the reliability of the two subscales were satisfactory with .742 for “social problems as rights violations” and .795 for “clients as experiencing rights violations.” A CFA (n = 199) confirmed the overall fit of the revised model with the two factors. Thus, the K-HRLSW is a reliable and valid measure that researchers can employ to assess Korean social workers’ human rights-related competencies in practice and their ability to promote human rights in social service settings.

Retraction: Long non-coding RNA ANRIL alleviates H2O2-induced injury by up-regulating microRNA-21 in human lens epithelial cellss.

Retraction: Long non-coding RNA ANRIL alleviates H2O2-induced injury by up-regulating microRNA-21 in human lens epithelial cellss.

Fluorescence Imaging of Diabetic Cataract-Associated Lipid Droplets in Living Cells and Patient-Derived Tissues.

Diabetic cataract (DC) surgery carries risks such as slow wound healing, macular edema, and progression of retinopathy and is faced with a deficiency of effective drugs. In this context, we proposed a protocol to evaluate the drug's efficacy using lipid droplets (LDs) as the marker. For this purpose, a fluorescent probe PTZ-LD for LDs detection is developed based on the phenothiazine unit. The probe displays polarity-dependent emission variations, i.e., lower polarity leading to stronger intensity. Especially, the probe exhibits photostability superior to that of Nile Red, a commercial LDs staining dye. Using the probe, the formation of LDs in DC-modeled human lens epithelial (HLE) cells is validated, and the interplay of LDs-LDs and LDs-others are investigated. Unexpectedly, lipid transfer between LDs is visualized. Moreover, the therapeutic efficacy of various drugs in DC-modeled HLE cells is assessed. Ultimately, more LDs were found in lens epithelial tissues from DC patients than in cataract tissues for the first time. We anticipate that this work can attract more attention to the important roles of LDs during DC progression.

AQP5 deficiency promotes the senescence of lens epithelial cells through mitochondrial dysfunction

Cataract is lens opacity, which is a common blinding eye disease worldwide. Aquaporin 5 (AQP5) is expressed in the human and mouse lenses. This study aimed to investigate the underlying mechanisms of AQP5 in the senescence of lens epithelial cells (LECs). Primary LECs were isolated and cultured from Aqp5+/+ and Aqp5−/− mice. Western blot or immunofluorescence staining of p16, Ki67, MitoSOX, JC-1 and phalloidin was used in the experiments to evaluate the changes in the primary LECs. The primary Aqp5−/− LECs showed increased p16 expression and mitochondrial reactive oxygen species, decreased mitochondrial membrane potential and activity, and cytoskeletal disorders. When the cells were pretreated with Mito-TEMPO, the Aqp5−/− mice showed decreased p16 expression, reduced mitochondrial dysfunction and cytoskeletal disorders. Our results revealed that AQP5 deficiency promotes the senescence of primary LECs through mitochondrial dysfunction. This provides a new perspective for the treatment of cataracts by regulating AQP5 expression.

Arginase-1 promotes lens epithelial-to-mesenchymal transition in different models of anterior subcapsular cataract

BackgroundArginase-1 (ARG1) promotes collagen synthesis and cell proliferation. ARG1 is highly expressed in various tumour cells. The mechanisms of ARG1 in epithelial-to-mesenchymal transition (EMT)-associated cataracts were studied herein.MethodsC57BL/6 mice, a human lens epithelial cell line (HLEC-SRA01/04), and human lens capsule samples were used in this study. The right lens anterior capsule of the mouse eye was punctured through the central cornea with a 26-gauge hypodermic needle. Human lens epithelial cells (HLECs) were transfected with ARG1-targeted (siARG1) or negative control siRNA (siNC). For gene overexpression, HLECs were transfected with a plasmid bearing the ARG1 coding sequence or an empty vector. Medium containing 0.2% serum with or without transforming growth factor beta-2 (TGF-β2) was added for 6 or 24 h to detect mRNA or protein, respectively. The expression of related genes was measured by quantitative real-time polymerase chain reaction (RT–qPCR), western blotting, and immunohistochemical staining. Transwell assays and wound healing assays were used to determine cell migration. Cell proliferation, superoxide levels, nitric oxide (NO) levels, and arginase activity were estimated using Cell Counting Kit-8 assays, a superoxide assay kit, an NO assay kit, and an arginase activity kit.ResultsARG1, alpha-smooth muscle actin (α-SMA), fibronectin, and Ki67 expression increased after lens capsular injury, while zonula occludens-1 (ZO-1) expression decreased.Fibronectin and collagen type I alpha1 chain (collagen 1A1) expression increased, and cell migration increased significantly in ARG1-overexpressing HLECs compared with those transfected with an empty vector after TGF-β2 treatment. These effects were reversed by ARG1 knockdown.The arginase-related pathway plays an important role in EMT. mRNAs of enzymes of the arginase-related pathway were highly expressed after ARG1 overexpression. ARG1 knockdown suppressed these expression changes.Numidargistat (CB-1158) dihydrochloride (CB-1158), an ARG1 inhibitor, suppressed TGF-β2-induced anterior subcapsular cataract (ASC) by reducing the proliferation of lens epithelial cells (LECs) and decreasing fibronectin, α-SMA, collagen 1A1, and vimentin expression.Compared with that in nonanterior subcapsular cataract (non-ASC) patients, the expression of ARG1, collagen 1A1, vimentin, fibronectin, and Ki67 was markedly increased in ASC patients.ConclusionsARG1 can regulate EMT in EMT-associated cataracts. Based on the pathogenesis of ASC, these findings are expected to provide new therapeutic strategies for patients.Graphical abstract

SUMO1-regulated DBC1 promotes p53-dependent stress-induced apoptosis of lens epithelial cells.

Deleted in breast cancer 1 (DBC1) was initially identified from a homozygously deleted region in human chromosome 8p21. It has been well established that DBC1 plays a dual role during cancer development. Depending on the physiological context, it can promote or inhibit tumorigenesis. Whether it plays a role in lens pathogenesis remains elusive. In the present study, we demonstrated that DBC1 is highly expressed in lens epithelial cells from different vertebrates and in retina pigment epithelial cells as well. Moreover, DBC1 is SUMOylated through SUMO1 conjugation at K591 residue in human and mouse lens epithelial cells. The SUMOylated DBC1 is localized in the nucleus and plays an essential role in promoting stress-induced apoptosis. Silence of DBC1 attenuates oxidative stress-induced apoptosis. In contrast, overexpression of DBC1 enhances oxidative stress-induced apoptosis, and this process depends on p53. Mechanistically, DBC1 interacts with p53 to regulate its phosphorylation status at multiple sites and the SUMOylation of DBC1 enhances its interaction with p53. Together, our results identify that DBC1 is an important regulator mediating stress-induced apoptosis in lens, and thus participates in control of lens cataractogenesis.

Contributed Session II: Ex-vivo human crystalline lenses geometrical changes during simulated disaccommodation.

The young crystalline lens changes its shape to focus targets at different distances, a capability (accommodation) that is lost with age. Quantifying crystalline lens morphology during accommodation and aging is essential for understanding basic mechanisms of function and disease (presbyopia and cataract). We studied the geometrical changes of the ex-vivo human crystalline lens while simulating different levels of physiological disaccommodation using a motorized lens-stretcher system designed for this purpose. 14 human lenses (11-54 y/o) from donor eyes were radially stretched mounted in the lens-stretcher and immersed in a cuvette filled with balanced salt solution for preservation purposes. Lens geometry and power were characterized using custom-developed high resolution 3-D optical coherence tomography (OCT) and laser ray tracing system coupled with the OCT. The lens thickness decreased linearly 81 microns/diopter (D) of simulated disaccommodation (-r=0.87, p<0.001), the diameter increased 76 microns/D (r=0.84, p<0.01), the radius of curvature of the anterior surface increased 0.63 mm/D (r=0.92, p<0.001), the lens surface area increased 1.9 mm2/D (r=0.62, p<0.01) and the lens volume remained constant. The same stretching displacement produced larger deformations in younger than in older lenses. Simultaneous high resolution optical and geometrical measurements of stretched lenses therefore match results in vivo and support the Helmholtz theory of accommodation.

Metformin protects human lens epithelial cells from high glucose-induced senescence and autophagy inhibition by upregulating SIRT1.

The aim of this study is to explore whether metformin (MET) protects the human lens epithelial cells (HLECs) from high glucose-induced senescence and to identify the underlying mechanisms. A cellular senescence model was established by treating HLE-B3 cells with D-glucose and then intervened with MET. Concentrations of high glucose (HG) and MET were detected using CCK-8 and western blot. qRT-PCR, western blot, and senescence-associated β-galactosidase (SA-β-gal) were performed to verify the protective effect of MET on senescent HLE-B3 cells. Additionally, western blot and qRT-PCR were conducted to detect the effects of MET on autophagy-related markers p62 and LC3, as well as SIRT1. In vitro, we observed apparent senescence in human lens epithelial cells (HLECs) under high glucose conditions. This was characterized by increased senescence-associated genes p21 and p53. However, the addition of MET significantly reduced the occurrence of HLECs senescence. We also observed that high glucose inhibited both autophagy and SIRT1, which could be restored by MET. Moreover, we verified that the anti-senescence effect of MET was mediated by SIRT1 using SIRT1 activators and inhibitors. We have demonstrated that autophagy and SIRT1 activity are inhibited in HLE-B3 cells using the HG induced senescence model. Furthermore, our results showed that MET can delay senescence by activating SIRT1 and autophagy. These findings suggest that MET may be a promising candidate for alleviating cataract development and provide a direction for further investigation into the underlying molecular mechanisms.

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.

Astaxanthin ameliorates oxidative stress in lens epithelial cells by regulating GPX4 and ferroptosis

Ferroptosis is a form of regulated cell death closely associated with oxidative stress and mitochondrial dysfunction and is characterised by the accumulation of reactive oxygen species (ROS) and lipid species and iron overload. Damage to human lens epithelial cells (LECs) is associated with age-related cataract progression. Astaxanthin (ATX), a carotenoid with natural antioxidant properties, counteracts ferroptosis in the treatment of various degenerative diseases. However, this mechanism has not been reported with respect to cataract treatment. In this study, the differential expression levels of glutathione peroxidase 4 (GPX4) in the lens of young and aged mice were analysed. Continuous ATX supplementation for 8 months upregulated GPX4 expression in the mouse LECs and delayed the progression of ferroptosis. Upon treatment with erastin, ROS and malondialdehyde accumulated and the mitochondrial membrane potential decreased. At the same time, the expressions of GPX4, SLC7A11, and ferritin were suppressed in human LECs. All of these phenomena were partially reversed by ATX and Fer-1, a ferroptosis inhibitor. This study confirmed that the ATX-mediated targeting of GPX4 might alleviate human LECs damage by inhibiting ferroptosis and ameliorating oxidative stress and that this could represent a promising therapeutic approach for age-related cataract.

Study of level of malondialdehyde and total antioxidant capacity (TAC) in human lens epithelial cells of diabetic and senile cataract patients

Study of level of malondialdehyde and total antioxidant capacity (TAC) in human lens epithelial cells of diabetic and senile cataract patients

Applying a Human Rights Lens to Poverty and Economic Inequality: The Experience of the South African Human Rights Commission

The Constitution of South Africa, 1996, is committed to redressing poverty and inequality. This is evident in its inclusion of a range of justiciable socio-economic rights along with a strong substantive right to equality and non-discrimination. The South African Human Rights Commission is a state institution established by the Constitution to support constitutional democracy. It has wide-ranging powers to investigate, monitor and protect human rights, including an express constitutional mandate in relation to socio-economic rights. This article examines how it has sought to apply its constitutional and legislative mandates to various manifestations of poverty and economic inequality in South Africa. It focuses on three broad areas of the Commission’s work with a view to identifying its achievements as well as some of the key challenges it has faced. Based on this analysis, the article concludes by reflecting on the broader implications of the experience of the Commission for fourth branch institutions, specifically national human rights institutions, that apply a human rights lens to poverty and economic inequality.