Breaking Barriers: Nanomedicine-Based Drug Delivery for Cataract Treatment.

Cataract is a leading cause of blindness globally, and its surgical treatment poses a significant burden on global healthcare. Pharmacologic therapies, including antioxidants and protein aggregation reversal agents, have attracted great attention in the treatment of cataracts in recent years. Due to the anatomical and physiological barriers of the eye, the effectiveness of traditional eye drops for delivering drugs topically to the lens is hindered. The advancements in nanomedicine present novel and promising strategies for addressing challenges in drug delivery to the lens, including the development of nanoparticle formulations that can improve drug penetration into the anterior segment and enable sustained release of medications. This review introduces various cutting-edge drug delivery systems for cataract treatment, highlighting their physicochemical properties and surface engineering for optimal design, thus providing impetus for further innovative research and potential clinical applications of anti-cataract drugs.

Effect of isoflurane anaesthetic time on ocular a-scan ultrasonography measures and their relationship to age and OCT measures in the Guinea pig.

A-scan ultrasonography enables precise measurement of internal ocular structures. Historically, its use has underpinned fundamental studies of eye development and aberrant eye growth in animal models of myopia; however, the procedure typically requires anaesthesia. Since anaesthesia affects intra-ocular pressure (IOP), we investigated changes in internal ocular structures with isoflurane exposure and compared measurements with those taken in awake animals using optical coherence tomography (OCT). Continuous A-scan ultrasonography was undertaken in tri-coloured guinea pigs aged 21 (n = 5), 90 (n = 5) or 160 (n = 5) days while anaesthetised (up to 36 min) with isoflurane (5% in 1.5L/min O2). Peaks were selected from ultrasound traces corresponding to the boundaries of the cornea, crystalline lens, retina, choroid and sclera. OCT scans (Zeiss Cirrus Photo 800) of the posterior eye layers were taken in 28-day-old animals (n = 19) and compared with ultrasound traces, with choroid and scleral thickness adjusted for the duration of anaesthesia based on the changes modelled in 21-day-old animals. Ultrasound traces recorded sequentially in left and right eyes in 14-day-old animals (n = 30) were compared, with each adjusted for anaesthesia duration. The thickness of the cornea was measured in enucleated eyes (n = 5) using OCT following the application of ultrasound gel (up to 20 min). Retinal thickness was the only ultrasound internal measure unaffected by anaesthesia. All other internal distances rapidly changed and were well fitted by exponential functions (either rise-to-max or decay). After 10 and 20 min of anaesthesia, the thickness of the cornea, crystalline lens and sclera increased by 17.1% and 23.3%, 0.4% and 0.6%, and 5.2% and 6.5% respectively, whilst the anterior chamber, vitreous chamber and choroid decreased by 4.4% and 6.1%, 0.7% and 1.1%, and 10.7% and 11.8% respectively. In enucleated eyes, prolonged contact of the cornea with ultrasound gel resulted in an increase in thickness of 9.3% after 10 min, accounting for approximately half of the expansion observed in live animals. At the back of the eye, ultrasound measurements of the thickness of the retina, choroid and sclera were highly correlated with those from posterior segment OCT images (R2 = 0.92, p = 1.2 × 10-13, R2 = 0.55, p = 4.0 × 10-4, R2 = 0.72, p = 5.0 × 10-6 respectively). Furthermore, ultrasound measures for all ocular components were highly correlated in left and right eyes measured sequentially, when each was adjusted for anaesthetic depth. This study shows that the depth of ocular components can change dramatically with anaesthesia. Researchers should therefore be wary of these concomitant effects and should employ adjustments to better render 'true' values.

A grape-supplemented diet prevented ultraviolet (UV) radiation-induced cataract by regulating Nrf2 and XIAP pathways.

The purpose of this study is to investigate if grape consumption, in the form of grape powder (GP), could protect against ultraviolet (UV)-induced cataract. Mice were fed with the regular diet, sugar placebo diet, or a grape diet (regular diet supplemented with 5%, 10%, and 15% GP) for 3 months. The mice were then exposed to UV radiation to induce cataract. The results showed that the GP diet dose-dependently inhibited UV-induced cataract and preserved glutathione pools. Interestingly, UV-induced Nrf2 activation was abolished in the groups on the GP diet, suggesting GP consumption may improve redox homeostasis in the lens, making Nrf2 activation unnecessary. For molecular target prediction, a total of 471 proteins regulated by GP were identified using Agilent Literature Search (ALS) software. Among these targets, the X-linked inhibitor of apoptosis (XIAP) was correlated with all of the main active ingredients of GP, including resveratrol, catechin, quercetin, and anthocyanins. Our data confirmed that GP prevented UV-induced suppression of XIAP, indicating that XIAP might be one of the critical molecular targets of GP. In conclusion, this study demonstrated that GP protected the lens from UV-induced cataract development in mice. The protective effects of GP may be attributed to its ability to improve redox homeostasis and activate the XIAP-mediated antiapoptotic pathway.

[Lens injury as a complication of intravitreal medication injection]. / Linsenverletzungen als Komplikation bei intravitrealer Medikamenteneingabe.

BACKGROUND: Intravitreal medication injections are an efficient and low-risk delivery technique for treating various retinal diseases. Rare serious complications include increased intraocular pressure, vitreous hemorrhage, retinal tears and detachment, intraocular inflammation and endophthalmitis. In the case series presented here, we report iatrogenic lens injuries caused by inadequate performance of intravitreal injections. METHODS: A multicenter data collection of patients treated with intravitreal injections with visible iatrogenic lens defects from 2016 to 2023 was retrospectively performed. RESULTS: Lens trauma after intravitreal injections was identified in six cases (69.3±6.5 years). While five cases were observed after anti-VEGF therapy, we identified lens injury after dexamethasone implantation in one patient. CONCLUSION: Iatrogenic lens injury during intravitreal injection is preventable with the correct injection technique. Knowledge of individual axis length and lens status also helps to avoid this complication.

Protection of Human Lens Epithelial Cells from Oxidative Stress Damage and Cell Apoptosis by KGF-2 through the Akt/Nrf2/HO-1 Pathway.

Oxidative stress exerts a significant influence on the pathogenesis of various cataracts by inducing degradation and aggregation of lens proteins and apoptosis of lens epithelial cells. Keratinocyte growth factor-2 (KGF-2) exerts a favorable cytoprotective effect against oxidative stress in vivo and in vitro. In this work, we investigated the molecular mechanisms of KGF-2 against hydrogen peroxide- (H2O2-) induced oxidative stress and apoptosis in human lens epithelial cells (HLECs) and rat lenses. KGF-2 pretreatment could reduce H2O2-induced cytotoxicity as well as reactive oxygen species (ROS) accumulation. KGF-2 also increases B-cell lymphoma-2 (Bcl-2), quinine oxidoreductase-1 (NQO-1), superoxide dismutase (SOD2), and catalase (CAT) levels while decreasing the expression level of Bcl2-associated X (Bax) and cleaved caspase-3 in H2O2-stimulated HLECs. LY294002, the phosphatidylinositol-3-kinase (PI3K)/Akt inhibitor, abolished KGF-2's effect to some extent, demonstrating that KGF-2 protected HLECs via the PI3K/Akt pathway. On the other hand, KGF-2 activated the Nrf2/HO-1 pathway by regulating the PI3K/Akt pathway. Silencing nuclear factor erythroid 2-related factor 2 (Nrf2) by targeted-siRNA and inhibiting heme oxygenase-1 (HO-1) through zinc protoporphyrin IX (ZnPP) significantly decreased cytoprotection of KGF-2. Furthermore, as revealed by lens organ culture assays, KGF-2 treatment decreased H2O2-induced lens opacity in a concentration-dependent manner. As demonstrated by these data, KGF-2 resisted H2O2-mediated apoptosis and oxidative stress in HLECs through Nrf2/HO-1 and PI3K/Akt pathways, suggesting a potential protective effect against the formation of cataracts.

Radiation-induced DNA Damage and Repair in Lens Epithelial Cells of both Ptch1(+/-) and Ercc2(+/-) Mutated Mice.

Epidemiological studies suggest an increased incidence and risk of cataract after low-dose (<2 Gy) ionizing radiation exposures. However, the biological mechanism(s) of this process are not fully understood. DNA damage and repair are thought to have a contributing role in radiation-induced cataractogenesis. Recently we have reported an inverse dose-rate effect, as well as the low-dose response, of DNA damage and repair in lens epithelial cells (LECs). Here, we present further initial findings from two mutated strains (Ercc2+/- and Ptch1+/-) of mice, both reportedly susceptible to radiation-induced cataract, and their DNA damage and repair response to low-dose and low-dose-rate gamma rays. Our results support the hypothesis that the lens epithelium responds differently to radiation than other tissues, with reported radiation susceptibility to DNA damage not necessarily translating to the LECs. Genetic predisposition and strain(s) of mice have a significant role in radiation-induced cataract susceptibility.

Evaluation of lens opacity due to inhibition of cholesterol biosynthesis using rat lens explant cultures.

Drug-induced lens opacity has the potential to cause blindness and is of concern in drug development. Inhibition of cholesterol biosynthesis is one of the causes of lens opacity. Lens opacity is only observed after chronic administration in in vivo nonclinical studies in drug development. Thus, to save resources (e.g., time and cost) and to reduce burden on animals, it is required to develop in vitro evaluation systems that can predict and avoid the risk of lens opacity earlier and easier. In this study, we investigated whether rat lens explant cultures could be useful for the evaluation of drug-induced lens opacity via inhibition of cholesterol biosynthesis. Nineteen drugs, including statins, allylamine, thiocarbamate, azole, and morpholine, which inhibit cholesterol biosynthesis, as well as a negative control (acetaminophen, rosiglitazone and troglitazone), were used. Rat lens explants were treated with drugs for 13 days at concentrations close to IC50 values or higher against cholesterol biosynthesis, and lens opacity (severity and region) was evaluated. In most cases, region-specific lens opacity limited in the equator to posterior pole, as observed in vivo was observed at IC50 values or higher concentrations. The severity of opacity was likely to be related to the inhibitory potency toward cholesterol biosynthesis, concentration of drugs distributed in the lens, or time of exposure. Furthermore, GSH levels were also involved in the deterioration of lens opacity. In conclusion, we demonstrated that rat lens explant cultures can be useful to assess the potential drug-induced lens opacity associated with inhibition of cholesterol biosynthesis and to elucidate the mechanisms of lens opacity.

Comparison of methods to experimentally induce opacification and elasticity change in ex vivo porcine lenses.

At the moment, cataract, which is the opacification of the eye's lens, can only be treated by surgery. In order to develop and test new pharmacological treatment strategies for the disease, there is a need for an appropriate in vitro model using ex vivo animal lenses. In this study, porcine lenses were incubated in either culture medium, glucose, triamcinolone acetonide, sodium chloride, hydrogen peroxide, sodium selenite, neutral buffered formalin, or were exposed to microwave heating to experimentally induce lens opacification. Changes in the lens morphology, weight, size, and elasticity were monitored 7 days after treatment. The fastest induction of dense opacification was seen in lenses exposed to sodium chloride, neutral buffered formalin, and microwave heating. No change in the size and weight of the lenses were detected, whereas loss in elasticity could be detected in lenses treated with formalin solution or microwave heating. Thus, neutral buffered formalin- and microwave-treated ex vivo porcine lenses seem to be a suitable model for mature cataracts, whereas hypertonic sodium chloride may be useful for studies on osmolarity-induced lens opacification.

An Atlas of Heparan Sulfate Proteoglycans in the Postnatal Rat Lens.

Purpose: The arrangement of lens cells is regulated by ocular growth factors. Although the effects of these inductive molecules on lens cell behavior (proliferation, survival, and fiber differentiation) are well-characterized, the precise mechanisms underlying the regulation of growth factor-mediated signaling in lens remains elusive. Increasing evidence highlights the importance of heparan sulfate proteoglycans (HSPGs) for the signaling regulation of growth factors; however, the identity of the different lens HSPGs and the specific roles they play in lens biology are still unknown. Methods: Semiquantitative real-time (RT)-PCR and immunolabeling were used to characterize the spatial distribution of all known HSPG core proteins and their associated glycosaminoglycans (heparan and chondroitin sulfate) in the postnatal rat lens. Fibroblast growth factor (FGF)-2-treated lens epithelial explants, cultured in the presence of Surfen (an inhibitor of heparan sulfate [HS]-growth factor binding interactions) were used to investigate the requirement for HS in FGF-2-induced proliferation, fiber differentiation, and ERK1/2-signaling. Results: The lens expresses all HSPGs. These HSPGs are differentially localized to distinct functional regions of the lens. In vitro, inhibition of HS-sulfation with Surfen blocked FGF-2-mediated ERK1/2-signaling associated with lens epithelial cell proliferation and fiber differentiation, highlighting that these cellular processes are dependent on HS. Conclusions: These findings support a requirement for HSPGs in FGF-2 driven lens cell proliferation and fiber differentiation. The identification of specific HSPG core proteins in key functional lens regions, and the divergent expression patterns of closely related HSPGs, suggests that different HSPGs may differentially regulate growth factor signaling networks leading to specific biological events involved in lens growth and maintenance.

Anti-cataract effects of coconut water in vivo and in vitro.

OBJECTIVE: To determine the anti-cataract effects of coconut water (CW) in vivo and in vitro, and to explore the potential pathogenic mechanism. METHODS: In this study, 48 male Sprague-Dawley rats were randomly divided into 4 groups: control (CO), diabetic (DM), diabetic treated with CW (DM + CW), and diabetic treated with Glibenclamide (DM + Gli). Except for the CO group, in the other three groups, intraperitoneal injection of STZ (60 mg/kg) was conducted to establish diabetic models. The experiment was conducted for 20 weeks. The slit-lamp examination was undertaken during the period of experiment (20 weeks), and then, all rats were sacrificed. The levels of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) in the left lens were measured by using biochemical assays. The right lens was used for pathological analysis. The rat lens epithelial cells (LECs) were cultured in vitro and the subcultured cell were divided into four groups, namely the normal glucose group (5 mmol /L glucose, Group I), the high glucose group (40 mmol/L glucose, Group II), high glucose +5% CW group (Group III), and high glucose +10% CW group (Group IV). LECs were cultured under the conditions as described above for 48 h. Cell proliferation and the morphological changes were observed with interted phase contrast microscope.The level of cell apoptosis was determined by flow cytometry. the level of SOD, MDA and GSH-Px were also detected. RESULTS: The lens opacity index decreased in diabetic rats, and LECs apoptosis ratio also decreased in high glucose environments that received CW. Under treatment with CW, reduced MDA level and elevated activities of SOD and GSH-Px were detected, both in vivo and in vitro experiments. The increased severity of cataract and LECs apoptosis were noted in diabetic rats that received normal water, while CW markedly mitigated the enhanced cataract severity and the reduction of LECs induced by diabetes mellitus. CONCLUSION: CW is a functional food that can protect the lens from diabetic cataract. The possible underlying mechanism may be partly explained via the decreased oxidative stress in lens. However, further research needs to be conducted to indicate the pathogenic mechanism of anti-diabetic effects of CW.

Metformin attenuates the epithelial-mesenchymal transition of lens epithelial cells through the AMPK/TGF-ß/Smad2/3 signalling pathway.

Posterior capsule opacification (PCO) is a common ocular fibrosis disease related to the epithelial-mesenchymal transition (EMT) of human lens epithelial cells (HLECs). However, safe and effective drugs that prevent or treat PCO are lacking. Metformin (Mtf) has been used to treat fibrosis-related diseases affecting many organs and tissues, but its effect on ocular fibrosis-related diseases is unclear. We investigated whether Mtf can inhibit EMT and fibrosis in HLECs to prevent and treat PCO and elucidated the potential molecular mechanism. Here, we established an HLEC model of TGF-ß-induced EMT and found that 400 µM Mtf inhibited vertical and lateral migration and EMT-related gene and protein expression in HLECs. Smad2/3 are downstream molecules of TGF-ß that enter the nucleus to regulate EMT-related gene expression during the occurrence and development of PCO. We revealed that Mtf suppressed TGF-ß-induced Smad2/3 phosphorylation and nuclear translocation. Mtf induces AMP-activated protein kinase (AMPK) phosphorylation. In this study, we found that Mtf induced the activation of AMPK phosphorylation in HLECs. To further explore the mechanism of Mtf, we pretreated HLECs with Compound C (an AMPK inhibitor) to repeat the above experiments and found that Compound C abolished the inhibitory effect of Mtf on HLEC EMT and the TGF-ß/Smad2/3 signalling pathway. Thus, Mtf targets AMPK phosphorylation to inhibit the TGF-ß/Smad2/3 signalling pathway and prevent HLEC EMT. Notably, we first illustrated the AMPK/TGF-ß/Smad2/3 signalling pathway in HLECs, which may provide a new therapeutic strategy for PCO.

Examining the effects of cigarette smoke on mouse lens through a multi OMIC approach.

Here, we report a multi OMIC (transcriptome, proteome, and metabolome) approach to investigate molecular changes in lens fiber cells (FC) of mice exposed to cigarette smoke (CS). Pregnant mice were placed in a whole-body smoke chamber and a few days later pups were born, which were exposed to CS for 5 hours/day, 5 days/week for a total of 3½ months. We examined the mice exposed to CS for CS-related cataractogenesis after completion of the CS exposure but no cataracts were observed. Lenses of CS-exposed and age-matched, untreated control mice were extracted and lens FC were subjected to multi OMIC profiling. We identified 348 genes, 130 proteins, and 14 metabolites exhibiting significant (p < 0.05) differential levels in lens FC of mice exposed to CS, corresponding to 3.6%, 4.3%, and 5.0% of the total genes, protein, and metabolites, respectively identified in this study. Our multi OMIC approach confirmed that only a small fraction of the transcriptome, the proteome, and the metabolome was perturbed in the lens FC of mice exposed to CS, which suggests that exposure of CS had a minimal effect on the mouse lens. It is worth noting that while our results confirm that CS exposure does not have a substantial impact on the molecular landscape of the mouse lens FC, we cannot rule out that CS exposure for longer durations and/or in combination with other morbidities or environmental factors would have a more robust effect and/or result in cataractogenesis.

Metformin alleviates oxidative stress-induced senescence of human lens epithelial cells via AMPK activation and autophagic flux restoration.

Cataracts are the leading cause of blindness worldwide owing to the increasing proportion of elderly individuals in the population. The purpose of this study was to investigate whether metformin could alleviate the occurrence and development of age-related cataract (ARC) and the underlying mechanism. In the present study, we established a senescence model induced by oxidative stress, which was confirmed by measuring ß-galactosidase activity, qRT-PCR and Western blotting. In addition, we showed that metformin alleviated the oxidative stress-induced senescence of HLE-B3 cells via the activation of AMPK. Next, we provided evidence that oxidative stress impaired autophagic flux and induced lysosomal dysfunction. Subsequently, we found that metformin restored autophagic flux that had been impaired by oxidative stress by activating AMPK. Additionally, we found that metformin suppressed HLE-B3 cell senescence by improving lysosomal function and inactivating mTOR. Furthermore, the inactivation of AMPK, impairment of autophagic flux and lysosomal dysfunction were observed in the human lens epithelium of ARC. In summary, our data suggest that the activation of AMPK may be a potential strategy for preventing ARC, and metformin may be an emerging candidate to alleviate the formation and development of ARC.

Taurine supplementation protects lens against glutathione depletion.

OBJECTIVE: Cataract which is defined as opacification of eye lens forms approximately 40% of total blindness causes all through the world. Age is the biggest risk factor for cataracts and oxidative stress is known to be one of the most important factors causing cataract formation. Age-related nuclear cataract (ARN) is associated with a loss of glutathione in the center of the lens. Taurine is an important antioxidant in lens tissue. Although, there is a high amount of taurine in lenses in early life, its concentration declines with age. In this study, we aimed to investigate the effects of supplemental taurine in lens tissues in an in vivo oxidative stress model which is induced by glutathione depletion to mimic ARN. MATERIALS AND METHODS: Glutathione depletion was induced in rabbits subcutaneously with l-Buthionine -(S,R)-sulfoximine (BSO)- a glutathione inhibitor and the rabbits were treated with taurine. Total GSH, reduced GSH, GSH/GSSG ratio and MDA levels were measured. RESULTS: BSO lowered the reduced GSH and total GSH levels and GSH/GSSG ratio. Taurine reversed these effects. On the other hand, BSO enhanced MDA level which is normalized by taurine. CONCLUSIONS: These findings suggest that glutathione depletion with BSO may be a useful model to mimic ARN and dietary intake of taurine, may have an important role in decelerating the process of cataract formation.

Protein posttranslational modification (PTM) by glycation: Role in lens aging and age-related cataractogenesis.

Crystallins, the most prevalent lens proteins, have no turnover throughout the entire human lifespan. These long-lived proteins are susceptible to post-synthetic modifications, including oxidation and glycation, which are believed to be some of the primary mechanisms for age-related cataractogenesis. Thanks to high glutathione (GSH) and ascorbic acid (ASA) levels as well as low oxygen content, the human lens is able to maintain its transparency for several decades. Aging accumulates substantial changes in the human lens, including a decreased glutathione concentration, increased reactive oxygen species (ROS) formation, impaired antioxidative defense capacity, and increased redox-active metal ions, which induce glucose and ascorbic acid degradation and protein glycation. The glycated lens crystallins are either prone to UVA mediated free radical production or they attract metal ion binding, which can trigger additional protein oxidation and modification. This vicious cycle is expected to be exacerbated with older age or diabetic conditions. ASA serves as an antioxidant in the human lens under reducing conditions to protect the human lens from damage, but ASA converts to the pro-oxidative role and causes lens protein damage by ascorbylation in high oxidation or enriched redox-active metal ion conditions. This review is dedicated in honor of Dr. Frank Giblin, a great friend and superb scientist, whose pioneering and relentless work over the past 45 years has provided critical insight into lens redox regulation and glutathione homeostasis during aging and cataractogenesis.

ZNF219 protects human lens epithelial cells against H2O2-induced injury via targeting SOX9 through activating AKT/GSK3ß pathway.

Opacity of the lens caused by cataracts could lead to severe visual impairment and even blindness. Oxidative stress caused by exposure of lens epithelial cells to hydrogen peroxide (H2O2) can lead to DNA damage and impair cell function. Therefore, how to prevent lens epithelial cells from being harmed by H2O2 is an urgent problem. The ZNF219 gene belongs to the Kruppel like zinc finger gene family, which is involved in a variety of biological processes. In this study, we found the low expression of ZNF219 in H2O2-induced HLE-B3 cells. We further noticed ZNF219 could improve the survival rate of H2O2-induced HLE-B3 cells, and inhibit the apoptosis and oxidative stress response. Mechanically, ZNF219 protected human lens epithelial cells against H2O2-induced injury via targeting SOX9 through activating AKT/GSK3ß pathway. We therefore thought ZNF219 was a key protective protein in the oxidative damage of human lens epithelial cells and the pathogenesis of cataract.

Suppression of epithelial to mesenchymal transition markers in mouse lens by a Smad7-based recombinant protein.

Cataracts, a clouding of the eye lens, are a leading cause of visual impairment and are responsible for one of the most commonly performed surgical procedures worldwide. Although generally safe and effective, cataract surgery can lead to a secondary lens abnormality due to transition of lens epithelial cells to a mesenchymal phenotype (EMT) and opacification of the posterior lens capsular bag. Occurring in up to 40% of cataract cases over time, posterior capsule opacification (PCO) introduces additional treatment costs and reduced quality of life for patients. Studies have shown that PCO pathogenesis is driven in part by TGF-ß, signaling through the action of the family of Smad coactivators to effect changes in gene transcription. In the present study, we evaluated the ability of Smad-7, a well characterized inhibitor of TGF-ß -mediated Smad signaling, to suppress the EMT response in lens epithelial cells associated with PCO pathogenesis. Treatment of lens epithelial cells with a cell-permeable form of Smad7 variant resulted in suppressed expression of EMT markers such as alpha smooth muscle actin and fibronectin. A single application of cell-permeable Smad7 variant in the capsular bag of a mouse cataract surgery model resulted in suppression of gene transcripts encoding alpha smooth muscle actin and fibronectin. These results point to Smad7 as a promising biotherapeutic agent for prevention or substantial reduction in the incidence of PCO following cataract surgery.

Circular RNA circZNF292 regulates H2 O2 -induced injury in human lens epithelial HLE-B3 cells depending on the regulation of the miR-222-3p/E2F3 axis.

Circular RNAs (circRNAs) play important roles in the pathogenesis of age-related cataract (ARC). CircRNA zinc finger protein 292 (circZNF292, hsa_circ_0004058) is downregulated in ARC lens capsules. Here, we focused on its precise roles in oxidative stress underlying the pathogenesis of ARC. CircZNF292, microRNA (miR)-222-3p, and E2F transcription factor 3 (E2F3) were quantified by quantitative real-time polymerase chain reaction or western blot. Cell viability was assessed by the cell counting kit-8 assay. Cell cycle distribution and apoptosis were detected by flow cytometry. The activities of superoxide dismutase, catalase, and malondialdehyde were measured using the corresponding assay kit. Targeted correlations among circZNF292, miR-222-3p, and E2F3 were verified by the dual-luciferase reporter, RNA immunoprecipitation and RNA pull-down assays. Our data showed that circZNF292 was downregulated in ARC tissues and H2 O2 -treated human lens epithelial B3 (HLE-B3) cells. Increased expression of circZNF292 alleviated H2 O2 -induced cell viability suppression, apoptosis promotion, and oxidative stress enhancement. Mechanistically, circZNF292 directly targeted miR-222-3p, and circZNF292 regulated E2F3 expression through miR-222-3p. MiR-222-3p was a functional mediator of circZNF292 in modulating H2 O2 -induced injury in HLE-B3 cells. Furthermore, reduced level of miR-222-3p ameliorated H2 O2 -induced HLE-B3 cell damage by upregulating E2F3. Our present study demonstrated that increased expression of circZNF292 ameliorated H2 O2 -induced injury in HLE-B3 cells at least in part through the miR-222-3p/E2F3 axis, highlighting a novel insight into the involvement of circRNAs in the pathogenesis of ARC.

A Potential Role for Fructosamine-3-Kinase in Cataract Treatment.

Cataracts are the major cause of blindness worldwide, largely resulting from aging and diabetes mellitus. Advanced glycation end products (AGEs) have been identified as major contributors in cataract formation because they alter lens protein structure and stability and induce covalent cross-linking, aggregation, and insolubilization of lens crystallins. We investigated the potential of the deglycating enzyme fructosamine-3-kinase (FN3K) in the disruption of AGEs in cataractous lenses. Macroscopic changes of equine lenses were evaluated after ex vivo intravitreal FN3K injection. The mechanical properties of an equine lens pair were evaluated after treatment with saline and FN3K. AGE-type autofluorescence (AF) was measured to assess the time-dependent effects of FN3K on glycolaldehyde-induced AGE-modified porcine lens fragments and to evaluate its actions on intact lenses after in vivo intravitreal FN3K injection of murine eyes. A potential immune response after injection was evaluated by analysis of IL-2, TNFα, and IFNγ using an ELISA kit. Dose- and time-dependent AF kinetics were analyzed on pooled human lens fragments. Furthermore, AF measurements and a time-lapse of macroscopic changes were performed on intact cataractous human eye lenses after incubation with an FN3K solution. At last, AF measurements were performed on cataractous human eyes after crossover topical treatment with either saline- or FN3K-containing drops. While the lenses of the equine FN3K-treated eyes appeared to be clear, the saline-treated lenses had a yellowish-brown color. Following FN3K treatment, color restoration could be observed within 30 min. The extension rate of the equine FN3K-treated lens was more than twice the extension rate of the saline-treated lens. FN3K treatment induced significant time-dependent decreases in AGE-related AF values in the AGE-modified porcine lens fragments. Furthermore, in vivo intravitreal FN3K injection of murine eyes significantly reduced AF values of the lenses. Treatment did not provoke a systemic immune response in mice. AF kinetics of FN3K-treated cataractous human lens suspensions revealed dose- and time-dependent decreases. Incubation of cataractous human eye lenses with FN3K resulted in a macroscopic lighter color of the cortex and a decrease in AF values. At last, crossover topical treatment of intact human eyes revealed a decrease in AF values during FN3K treatment, while showing no notable changes with saline. Our study suggests, for the first time, a potential additional role of FN3K as an alternative treatment for AGE-related cataracts.

KPNA4 is involved in cataract formation via the nuclear import of p53.

KPNA4 (also called importin-α3) belongs to the importin α adaptor proteins family, which orchestrates classical nuclear transport processes, importin-α/importin-ß1 pathway, and involves in cellular homeostasis. Disruption of balanced transport pathways may result in ectopic nuclear proteins and eventually cause diseases, mainly under the situation of cellular stress, such as oxidative stress. Little evidence is available on its cellular functions for high specific expression in lens. We firstly studied the role of KPNA4 in cataract formation. Lens defects were observed at an early age in kpna4 gene knockout zebrafish, generated by the CRISPR/Cas9 system. Those phenotype, including cloudy center part of the lens, via bright field microscopy, and the thinning of the LE layer, wider space between the adjacent LE and LF cells, irregular cells morphology and the increased number of holes inside the LE cells, which were detected by transmission electron microscopy, recapitulate the clinical features of cataract patients. As the p53-specific adaptor of the nuclear import, KPNA4 upregulated with the same pattern of p53 in hydrogen peroxide-induced apoptosis in human lens epithelia cells. Furthermore, the loss of Kpna4 resulted in the accumulation of p53 in the center of lens. Taken together, we showed that KPNA4 was involved in the formation of cataract, likely by mediating p53 nuclear transport.