Development Of Diabetic Cataract Research Articles

Preventive Effect of Astaxanthin on Diabetic Cataracts and Its Protective Effect on Lens Epithelial Cells

To better combat the development of diabetic cataracts (DC), we conducted a study on the use of astaxanthin (ATX) as an innovative antioxidant. Our research found that ATX exhibited good biocompatibility with lens epithelial cells (LECs) and increasing its concentration did not reduce cell activity. In the presence of high glucose, LECs experienced elevated oxidative stress levels, leading to a significant inhibition of their activity. However, the addition of ATX increased the antioxidant levels in LECs, resulting in a concentration-dependent increase in cell activity. Furthermore, when tested on diabetic rat models, higher concentrations of ATX application effectively prevented the development of DC and suppressed the level of oxidative stress in the lens. Our findings highlight the strong antioxidant effect of ATX, which can safeguard LEC activity in the presence of high glucose and inhibit the development of DC.

Methyltransferase METTL3-mediated maturation of miR-4654 facilitates high glucose-induced apoptosis and oxidative stress in lens epithelial cells via decreasing SOD2.

N6-methyladenosine (m6 A) modification has been reported to have roles in modulating the development of diabetic cataract (DC). Methyltransferase-like 3 (METTL3) is a critical m6 A methyltransferase involving in m6 A modification activation. Here, we aimed to explore the action and mechanism of METTL3-mediated maturation of miR-4654 in DC progression. Human lens epithelial cells (HLECs) were exposed to high glucose (HG) to imitate DC condition invitro. Levels of genes and proteins were tested via qRT-PCR and western blotting assays. The proliferation and apoptosis of HLECs were evaluated by cell counting kit-8, 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays, respectively. Oxidative stress was analyzed by detecting the contents of reactive oxygen species (ROS), superoxide dismutase (SOD) and malondialdehyde (MDA). The binding of miR-4654 and SOD2 was confirmed by dual-luciferase reporter assay. The m6 A-RNA immunoprecipitation (MeRIP) assay detected the m6 A modification profile. Thereafter, we found that miR-4654 expression was elevated in DC samples and HG-induced HLECs. MiR-4654 knockdown reversed HG-mediated apoptosis and oxidative stress in HLECs. Mechanistically, miR-4654 directly targeted SOD2, silencing of SOD2 abolished the protective effects of miR-4654 knockdown on HLECs under HG condition. In addition, METTL3 induced miR-4654 maturation through promoting pri-miR-4654 m6 A modification, thereby increasing miR-4654 content in HLECs. METTL3 was highly expressed in DC samples and HG-induced HLECs, METTL3 deficiency protected HLECs against HG-mediated apoptotic and oxidative injury via down-regulating miR-4654. In all, METTL3 induced miR-4654 maturation in a m6 A-dependent manner, which was then reduced SOD2 expression, thus promoting apoptosis and oxidative stress in HLECs, suggesting a novel path for DC therapy.

Butein Inhibits the Glycation of α-Crystallin: An Approach in Prevention of Retinopathy.

The aggregation of lens proteins induced by glycation is one of the key drivers of diabetic retinopathy and development of diabetic cataracts. Moreover, glycation also causes numerous alterations not only to the tertiary structure of lens proteins but also to serum proteins. There are also evidences of covalent crosslinking among lens crystallins resulting in development of cataract. In this article, the inhibitory potential of butein was tested against the glucose induced glycation and the aggregation α-crystallin (α-cry). The results showed that there was inhibition of advanced glycation products (78.28%) and early glycation products (86.30%) following the treatment of butein. Additionally, the presence of butein caused a significant improvement in the tested biochemical markers of glycation. The treatment with butein reduced the free lysine modification to 23.67%. The secondary and tertiary structural distortions of α-cry were also protected. The mechanism of inhibition further investigated at the molecular level using biophysical and computational techniques. The interaction data showed the butein exhibited strong affinity towards the α-cry. The binding event was entropically driven and energetically favourable. The Gibb's free energy of the interaction was found to be -5.99 to -7.17 kcal mol-1. The binding site of butein in α-cry was deciphered by molecular docking and the dynamics was studied using molecular dynamics (MD) simulations. The simulation data showed that butein formed stable complex with α-cry under physiological conditions. Most of the tested parameters from molecular simulations, such as secondary structure, was found to be stable. The data clearly show the potential of butein in inhibiting the glycation induced aggregation of α-cry and hence can be developed as useful inhibitor in the management of diabetic cataract and retinopathy.

The interaction between autophagy and the epithelial-mesenchymal transition mediated by NICD/ULK1 is involved in the formation of diabetic cataracts

BackgroundCataracts are the leading cause of blindness and a common ocular complication of diabetes. The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) and altered autophagic activity occur during the development of diabetic cataracts. The disturbed interaction of autophagy with EMT in LECs stimulated by high glucose levels may participate in cataract formation.MethodsA rat diabetic cataract model induced by streptozotocin (STZ) and human lens epithelial cells (HLE-B3) stimulated with a high glucose concentration were employed in the study. These models were treated with rapamycin (an inhibitor of mammalian target of rapamycin (mTOR)), and N-(N-[3,5-difluorophenacetyl]-1-alanyl)-S-phenylglycine t-butyl ester (DAPT, an inhibitor of γ-secretase) alone or in combination. Lens opacity was observed and photographed under a slit-lamp microscope. Histological changes in paraffin sections of lenses were detected under a light microscope after hematoxylin and eosin staining. Alterations of autophagosomes in LECs were counted and evaluated under a transmission electron microscope. The expression levels of proteins involved in the EMT, autophagy, and the signaling pathways in LECs were measured using Western blotting and immunofluorescence staining. Cell migration was determined by performing transwell and scratch wound assays. Coimmunoprecipitation (Co-IP) was performed to verify protein-protein interactions. Proteins were overexpressed in transfected cells to confirm their roles in the signaling pathways of interest.ResultsIn LECs, a high glucose concentration induces the EMT by activating Jagged1/Notch1/Notch intracellular domain (NICD)/Snail signaling and inhibits autophagy through the AKT/mTOR/unc 51-like kinase 1 (ULK1) signaling pathway in vivo and in vitro, resulting in diabetic cataracts. Enhanced autophagic activity induced by rapamycin suppressed the EMT by inducing Notch1 degradation by SQSTM1/p62 and microtubule-associated protein light chain 3 (LC3) in LECs, while inhibition of the Notch signaling pathway with DAPT not only prevented the EMT but also activated autophagy by decreasing the levels of NICD, which bound to ULK1, phosphorylated it, and then inhibited the initiation of autophagy.ConclusionsWe describe a new interaction of autophagy and the EMT involving NICD/ULK1 signaling, which mediates crosstalk between these two important events in the formation of diabetic cataracts. Activating autophagy and suppressing the EMT mutually promote each other, revealing a potential target and strategy for the prevention of diabetic cataracts.

MDM2-mediated ubiquitination of LKB1 contributes to the development of diabetic cataract

Diabetic cataract (DC) is a common complication of diabetes mellitus. The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a crucial event in the development of DC. Murine double minute 2 (MDM2) is an E3 ubiquitin ligase that promotes EMT by regulating diverse targets. However, little is known about how MDM2 is involved in the pathogenesis of DC. We found the mRNA and protein levels of MDM2 were up-regulated in the lens of DC patients and rats. Thus, high glucose (HG)-induced human lens epithelial cells (HLECs) were constructed for further investigation. The results showed that the level of MDM2 was increased in HG-cultured HLECs, and the MDM2 knockdown alleviated HG-induced abnormal migration, EMT, and oxidative stress damage. Moreover, co-immunoprecipitation and ubiquitination assays demonstrated that MDM2 down-regulated LKB1 expression by ubiquitination degradation. LKB1 was found to be lower expressed in human and rat DC lenses, and HG-stimulated HLECs. Also, LKB1 overexpression mitigated HG-induced dysfunction of HLECs. Finally, our data showed that the changes related to EMT and oxidative stress induced by MDM2 knockdown were restored by down-regulation of LKB1. Together, MDM2 may involve in the pathogenesis of DC through down-regulating LKB1. MDM2 might be an effective therapeutical target of DC.

Oxidative Stress-Induced TRPV2 Expression Increase Is Involved in Diabetic Cataracts and Apoptosis of Lens Epithelial Cells in a High-Glucose Environment.

Cataracts are a serious complication of diabetes. In long-term hyperglycemia, intracellular Ca2+ concentration ([Ca2+]i) and reactive oxygen species (ROS) are increased. The apoptosis of lens epithelial cells plays a key role in the development of cataract. We investigated a potential role for transient receptor potential vanilloid 2 (TRPV2) in the development of diabetic cataracts. Immunohistochemical and Western blotting analyses showed that TRPV2 expression levels were significantly increased in the lens epithelial cells of patients with diabetic cataracts as compared with senile cataract, as well as in both a human lens epithelial cell line (HLEpiC) and primary rat lens epithelial cells (RLEpiCs) cultured under high-glucose conditions. The [Ca2+]i increase evoked by a TRPV2 channel agonist was significantly enhanced in both HLEpiCs and RLEpiCs cultured in high-glucose media. This enhancement was blocked by the TRPV2 nonspecific inhibitor ruthenium red and by TRPV2-specific small interfering (si)RNA transfection. Culturing HLEpiCs or RLEpiCs for seven days in high glucose significantly increased apoptosis, which was inhibited by TRPV2-specific siRNA transfection. In addition, ROS inhibitor significantly suppressed the ROS-induced increase of TRPV2-mediated Ca2+ signal and apoptosis under high-glucose conditions. These findings suggest a mechanism underlying high-glucose–induced apoptosis of lens epithelial cells, and offer a potential target for developing new therapeutic options for diabetes-related cataracts.

A Review on Association Between Diabetes Mellitus and Cataract Formation

Major cause of blindness among diabetic patients is cataract both in developed and developing countries. Diabetic ocular complications are most common in both type-1 and type-2 diabetes, considering the fifth most common cause of legal blindness. This review aims to systematically evaluate the studies on occurrence of cataract formation among diabetic patients, types of cataract and its mechanisms of pathogenesis. According to WHO, cataract is 33% of all type of visual impairment. Prevalence of cataract increased with increasing age in both younger and older onset diabetic persons. Females had higher rates than males. The pathogenesis of diabetic cataract development is still not fully understood. Population-based studies have greatly increased our knowledge concerning the association between diabetes and cataract formation and have defined risk factors for the development of cataract. Simply diabetic cataracts are characterized by cortical or posterior sub-capsular opacities. Aldose reductase and polyol are responsible for diabetes ocular complications. Mechanisms of diabetic cataractogenesis have been studied in less detail than those of other diabetic complications. Both animal and human studies support important contribution of increased aldose reductase activity. Several clinical studies investigated the role of phacoemulsification surgery and its post-surgery complications. Researchers are trying to develop aldose reductase inhibitors and antioxidants, may be effective treatment to prevent or cure diabetes cataract.

Repression of Polyol Pathway Activity by Hemidesmus indicus var. pubescens R.Br. Linn Root Extract, an Aldose Reductase Inhibitor: An In Silico and Ex Vivo Study

Development of diabetic cataract is mainly associated with the accumulation of sorbitol via the polyol pathway through the action of Aldose reductase (AR). Hence, AR inhibitors are considered as potential agents in the management of diabetic cataract. This study explored the AR inhibition potential of Hemidesmus indicus var. pubescens root extract by in silico and ex vivo methods. Molecular docking studies (Auto Dock tool) between β-sitosterol, hemidesminine, hemidesmin-1, hemidesmin-2, and AR showed that β-sitosterol (− 10.2 kcal/mol) and hemidesmin-2 (− 8.07 kcal/mol) had the strongest affinity to AR enzyme. Ex vivo studies were performed by incubating isolated goat lenses in artificial aqueous humor using galactose (55 mM) as cataract inducing agent at room temperature (pH 7.8) for 72 h. After treatment with Vitamin E acetate − 100 µg/mL (standard) and test extract (500 and 1000 µg/mL) separately, the estimation of biochemical markers showed inhibition of lens AR activity and decreased sorbitol levels. Additionally, extract also normalized the levels of antioxidant markers like SOD, CAT, GSH. Our results showed evidence that H. indicus var. pubescens root was able to prevent cataract by prevention of opacification and formation of polyols that underlines its potential as a possible therapeutic agent against diabetic complications.Graphic

LncRNA MALAT1 Regulates miR-144-3p to Facilitate Epithelial-Mesenchymal Transition of Lens Epithelial Cells via the ROS/NRF2/Notch1/Snail Pathway.

Diabetic cataract is a common complication of diabetes. The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a key event in the development of diabetic cataracts. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been reported to be highly expressed in different tissues of diabetic patients. This study is aimed at investigating the function and mechanism of MALAT1 in the regulation of EMT in human LECs under high glucose conditions. MALAT1, α-smooth muscle actin (α-SMA), fibronectin (FN), and nuclear factor erythroid-derived 2-like 2 (NRF2) were highly expressed in the LECs of diabetic cataract patients and in the human LECs under high glucose conditions; meanwhile, the decreased expressions of E-cadherin and zonula occludens 1 (ZO-1) were detected. Knockdown of MALAT1 could significantly reduce ROS, prevent EMT, arrest S phase cell cycle, and suppress the expression of total NRF2 and its nucleus translocation in LECs. Furthermore, after NRF2 was knocked down, total NRF2, α-SMA, and FN in cells, and NRF2, Notch intracellular domain (NICD), and Snail were decreased in the nucleus. Using bioinformatics methods, we predicted that MALAT1 and NRF2 shared the same microRNA-144-3p (miR-144-3p) combining site. Luciferase reporter coupled with qRT-PCR assays revealed that miR-144-3p was a target of MALAT1, which was confirmed to downregulate miR-144-3p in the LECs. In addition, after transfection of miR-144-3p mimics or inhibitor, western blot assay demonstrated that miR-144-3p negatively regulated the expression of total NRF2, α-SMA, and FN in cells, and NRF2, NICD, and Snail in the nucleus without affecting Kelch-like ECH-associated protein 1 (KEAP1). Finally, we confirmed that transfection of shMALAT1 inhibited NRF2 expression, and its mediated EMT could be rescued by miR-144-3p inhibitor; transfection of pcDNA3.1-MALAT1 promoted NRF2 expression, and its mediated EMT could be reversed by miR-144-3p inhibitor. In summary, we demonstrate that MALAT1 regulates miR-144-3p to facilitate EMT of LECs via the ROS/NRF2/Notch1/Snail pathway.

Citrus hystrix leaf extract attenuated diabetic-cataract in STZ-rats.

Diabetic cataract causes severe vision loss. This study evaluated the effects of hesperidin-standardized Citrus hystrix leaf flavonoids-rich extract (CLE) on diabetic-cataract development. Streptozotocin-induced diabetic rats were orally given 150 and 300mg CLE/kg body-weight. These were compared with non-treated diabetic or healthy rats as controls, over 8weeks. The CLE gradually attenuated fasting blood glucose (FBG), biomarkers for inflammation (Tumor necrosis factor alpha TNF-α; prostaglandin E2 PGE2); vascular permeability, (Vascular endothelial growth factor VEGF); and oxidative stress, (malondialdehyde MDA). The diabetic cataract was significantly mitigated by the 150mg CLE/kg dose. Good correlations were found between cataract incidence with FBG (r2 =0.90), serum PGE2 (r2 =0.91), MDA (r2 =0.99), VEGF (r2 =0.71), but not with TNF-α levels (r2 =0.49) suggesting the serum FBG, PGE2, MDA, and possibly the VEGF levels may help to predict the cataract risks. The CLE mitigated cataract probably by attenuating hyperglycaemia, inflammation, lens fluid influx, vascular leakage, lens osmotic-imbalance, and fibers over-hydration. PRACTICAL APPLICATIONS: The study shows the flavonoids-rich Citrus hystrix leaf consumption, effectively attenuated diabetes (fasting blood glucose) and mitigated diabetic cataract. It help reduce diabetes-related hyperglycaemia, oxidative stress, inflammation, and vascular leakage. The evidences were the CLE consumptions reduced the serum biomarkers tumor necrosis factor-alpha TNF-α; prostaglandin E2 PGE2, vascular endothelial growth factor (VEGF), and malondialdehyde (MDA). The C. hystrix leaf contains hesperidin, apiin, diosmin, saponarin, apigetrin, rutin and xanthotoxol, and other flavonoid glucosides. The study also showed good correlations between cataract incidence with fasting blood glucose FBG (r2 =0.90), serum PGE2 (r2 =0.91), and MDA (r2 =0.99), and less closely with VEGF (r2 =0.71) suggesting these serum biomarkers may help predict cataract risks. The CLE indicated cataract mitigation properties probably by attenuating FBG, inflammation, lens fluid influx, lens osmotic-imbalance, and fibers over-hydration.

Role of lncRNA NEAT1 mediated by YY1 in the development of diabetic cataract via targeting the microRNA-205-3p/MMP16 axis.

We aimed at investigating the possible role and mechanism of NEAT1 in the pathogenesis of diabetic cataract. YY1 and NEAT1 expressions in anterior lens capsule collected from diabetic cataract (DC) patients and normal controls were examined by quantitative real-time polymerase chain reaction (qRT-PCR) analysis, and their correlation was analyzed. The binding site between YY1 and NEAT1 sequences was predicted by JASPAR and detected by Dual-Luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay. The proliferation and apoptosis of high-glucose-induced cells with NEAT1 knockdown were detected. Potential downstream targets of NEAT1 were predicted by bioinformatics and detected by Dual-Luciferase reporter assay. YY1 and NEAT1 expressions in the anterior capsule tissue of DC lens were remarkably reduced and positively correlated. Dual-Luciferase reporter assay and ChIP confirmed that YY1 could bind to locus 2 of NEAT1. Knockdown of NEAT1 inhibited proliferation while promoted apoptosis under high glucose conditions. Further mechanism studies revealed that knockdown of NEAT1 could upregulate microRNA-205-3p, and MMP16 was a potential target of miR-205. The low expression of YY1 induces NEAT1 downregulation, which regulates microRNA-205-3p/MMP16 axis and thus participates in the development of DC.

Effects of D-Limonene on aldose reductase and protein glycation in diabetic rats

Diabetes mellitus and hyperglycemia can lead to other health complications. The pathogenesis of diabetes mellitus can affect numerous tissues in the eye structure and cataracts are one of the major causes of visual impairment in diabetes mellitus patients. In this study, we aim to investigate the ability of D-limonene to inhibit aldose reductase hypoglycemic activity in lens organ culture and its anti-glycating properties in STZ-induced cataracts of rats with diabetes. D-limonene repressed aldose reductase in-vitro with IC50 ranges of ~13.9 ± 0.31 µg/mL in an uncompetitive manner. This compound also prevented hyperglycemic induced increases in aldose reductase activity, accumulation of sorbitol, altered crystalline proteins (α, β and γ), and opacification of the rat lens in ex-vivo lens organ culture. Supplementation of D-limonene in STZ-induced diabetic rats restored these changes and delayed the progression of cataracts. This study demonstrates that D-limonene is a pharmaceutically active component that inhibits rat-lens aldose reductase. Therefore, this study showed that D-limonene prevents advanced glycation end product formation contributing to the integrity of α-crystallin chaperone activity and delays cataract development. It has been concluded, D-limonene has a role in inhibiting aldose reductase activity and advanced glycation end products formation in vivo, and in delaying the development of diabetic cataracts. Further studies of D-limonene are needed to assess other complications in DM as they may provide additional evidence for establishing D-limonene as a potential pharmacological target therapy for diabetes mellitus complications.

High glucose: activating autophagy and affecting the biological behavior of human lens epithelial cells.

To clarify the effect of autophagy on human lens epithelial cells (HLECs) under high glucose conditions. HLECs were cultured with different concentrations of glucose and 3-methyladenine (3-MA); the expression of autophagy-related protein LC3B was detected by Western blotting and immunofluorescence histochemistry. The migration of HLECs was quantified by scratch wound assay and the expression of transforming growth factor-β (TGF-β) was measured by real-time polymerase chain reaction. Compared with 5 mmol/L normal glucose treatment, 40 mmol/L glucose treatment can significantly increase the generation of autophagosome in HLECs, which could be inhibited by 0.375 mmol/L 3-MA treatment. The migration of HLECs and the expression of TGF-β in HLECs induced by high glucose were significantly suppressed by 0.375 mmol/L 3-MA treatment. Autophagy promotes HLECs cell migration and increases the expression of TGF-β after exposed to high glucose, which may relate to the development of diabetic cataract.

Glucose Metabolism in Cardiac Hypertrophy and Heart Failure.

Glucose Metabolism in Cardiac Hypertrophy and Heart Failure.

Investigation of expression and effects of TGF-β1 and MMP-9 in lens epithelial cells of diabetic cataract rats.

Expressions and effects of transforming growth factor- 1 (TGF-β1) and matrix metalloproteinase-9 (MMP-9) in lens epithelial cells (LECs) of diabetic cataract rats were investigated. A total of 40 female Sprague-Dawley rats were randomly divided into study and control group. Rats in study group were successfully modeled diabetic cataract rats, and rats in control group were normal rats. Immunohistochemical staining was used to determine positive and negative granules in cytoplasm, and image proplus image analysis system to calculate the integral optical density of the average positive area. Quantitative analysis was performed on TGF-β1 and MMP-9 in LECs of rats in study and control groups at the 2nd and 4th weekends. There were no statistically significant differences in length and age between the two groups of rats (P>0.05). Glucose concentration in the blood of rats in study group after modeling was significantly higher than that before modeling (P<0.001), and that after modeling was significantly higher in study group than that in control group (P<0.001). The expression of TGF-β1 protein in LECs of rats in study group at T2 (the 4th weekend) was significantly higher than that at T1 (the 2nd weekend) (P<0.001), and that of TGF-β1 protein was significantly higher in study group than that in control group at T1 and T2 (P<0.001). The expression of MMP-9 protein in LECs of rats in study group at T2 was significantly higher than that at T1 (P<0.001), and that of MMP-9 protein was significantly higher in study group than that in control group at T1 and T2 (P<0.001). The TGF-β1 expression was positively correlated with the MMP-9 expression in LECs of diabetic cataract rats (r=0.825, P<001). The increased expression of MMP-9 and TGF-β1 may play an important role in the occurrence and development of diabetic cataract.

Assessing the changes in eye optics and visual functions in patients with insulin-dependent type 2 diabetes mellitus and their relationship with blood glucose level

Purpose: To assess the changes in eye optics and visual functions depending on the level of blood sugar and glycated hemoglobin (HbA1c) in insulin-dependent type 2 diabetes mellitus (IPSD) patients with excessive body weight, who receive long-term insulin therapy.Material and methods. 32 patients (64 eyes), of which 84.4 % were women and 15.6 % men, with insulin-dependent diabetes mellitus (IPSD) but without severe general diabetic complications or concomitant eye pathology were monitored ophthalmologically for 3 years. The average duration of insulin therapy was 6 years. The average age of the patients was 60.94 ± 1.04 years; average weight, 89.1 ± 14.8 kg; average height, 163.8 ± 7.3 cm; average body mass index, 31.3 ± 4.8 kg/m2. The level of blood glucose level was determined daily with individual Accu-Check and/or OneTouch select glucometers, supplemented by scheduled monthly examinations with an endocrinologist. The level of glycated hemoglobin (HbA1c) was determined once every 3–6 months. Vision was measured by international requirements for patients with diabetes using the ETDRS (Early Treatment Diabetic Retinopathy Study Research Group) system with an ESV-3000 device. To assess lens transparency, the international Lens Opacities Classification System III (LOCS III) was used. Glycaemia level was monitored by the patients themselves with the help of individual blood glucose meters and by endocrinologists in scheduled monthly checkups. HbA1c level was measured once every 3 to 6 months.Results. Over the follow-up period, the subjective visual acuity slightly deteriorated. The anterior segment remained practically unchanged, the vitreous body showed a destruction increase, the state of the retina remained stable and conformed to that of nonproliferative diabetic retinopathy. The glucose level showed a significant drop, while the level of glycated hemoglobin HbA1c practically remained constant. The LOCS III criteria showed an increased clarity of the lens nucleus (NO), a worse transparency of cortical layers (C) deteriorated; the NC nucleus colour and P parameters of the posterior subcapsular layer practically remained the same. Conclusions. According to our data, during the development of diabetic cataracts in patients with type 2 IPSD, NO of the lens changes first followed by C changes (they become worse). With the normalization of glycemia level, diabetic retinopathy does not progress, the NO of the lens can improve, and the NC and P do not change. Normalization of glycemia is not a retarding factor for the already existing changes in C or the state of the vitreous. HbA1c is a marker and trigger for possible lens changes in patients with type 2 diabetes and prolonged insulin therapy. HbA1с is effective for tracking the dynamics of changes in the eye in these patients. The fact that the positive correlation of HbA1c and C at follow-up start changed to the negative correlation toward the end of the study indicates a disruption in lens state compensation and does not cancel the negative dynamics of state C even with a decrease in the level of HbA1c.

The expression change of autophagy-related factors in lens epithelial cells of diabetic mice

Objective To investigate the role of autophagy in the development of diabetic cataract by detecting the expression of autophagy-related factors (BECN1, LC3B, P62) in diabetic mouse lens epithelial cells. Methods Eighty C57BL/6 male mice were selected.Fifty C57 mice were consecutively dosed with streptozotocin (STZ) 50 mg/(kg·d) by intraperitoneal injection to induce type 1 diabetes mellitus model, and served as the model group; the remaining 30 mice were injected with appropriate dose of citrate buffer, and served as the control group.The fasting plasma glucose was tested by collecting the caudal vein blood in the model group.The morphological changes of autophagy of lens epithelial cells were observed by transmission electron microscopy.The expression and localization of LC3B and P62 protein were detected by immunohistochemistry.PCR was used to detect the expression of BECN1, LC3B and P62 mRNA in the anterior capsule.The relative expression of autophagy-related proteins in the anterior capsule was detected by Western blot.The use of animals complied with Regulations on the Management of Experimental Ainimals from Shandong Eye Institute. Results Compared with the control group, transmission electron microscopy revealed that the autophagosomes of lens epithelial cells in model group was large and contained more mitochondria.Immunohistochemical method showed that the expression of LC3B and P62 proteins in the anterior capsule tissue of experiment group was stronger than that of the control group.The relative expression level of BECN1, LC3B and P62 mRNA in the experiment group was 1.48±0.10, 2.62±0.15 and 1.89±0.20, respectively, which was higher than 1.10±0.02, 1.10±0.05 and 1.01±0.01 in the control group, with significant differences between the two groups (t=6.64, 14.25, 6.14; all at P<0.05). The relative expression of BECN1, LC3B and P62 protein in the experiment group was 1.50±0.10, 1.24±0.09 and 3.19±1.04, respectively, which was higher than 1.00±0.00, 1.00±0.00 and 1.00±0.00 in the control group, with significant differences between the two groups (t=8.75, 6.10, 3.65; all at P<0.05). Conclusions The phenomenon of autophagy in lens epithelial cells of diabetic mice is abnormal, and autophagy dysfunction may play an important role in the formation of diabetic cataract. Key words: Diabetic cataract; Autophagy; Lens epithelial cells; BECN1; LC3B; P62

Vaccinium Extracts as Modulators in Experimental Type 1 Diabetes.

Antihyperglycemic effects of four extracts obtained from leaves and fruits of Vaccinium myrtillus and Vaccinium corymbosum were assessed in diabetic rats. In addition, the effects of extracts on diabetic-related complications such as the development of diabetic cataract and oxidative stress were evaluated. Type 1 diabetes was induced with a single dose of streptozotocin in Wistar rats. The rats were randomly divided into seven equal groups: NC-normal control, DC-diabetic control, PC-positive control treated with metformin, VML-received V. myrtillus leaf extract, VMLF-received VML and fruit extract, VCL-received V. corymbosum leaf extract, and VCLF-received VCL and fruit extract. Body weight and glucose levels were monitored every second week. After 8 weeks of treatment, serum glucose, insulin, and malondialdehyde were measured. Lenses were removed after sacrifice and eight lenses from each group were randomly selected for evaluation of cataract development. A decrease in body weight was observed in all diabetic groups in the first weeks. In the VML group, no significant decrease was observed. Glucose levels during the experiment were high in DC, PC, and VCL groups, with no improvement during the 8 weeks. In VML, VMLF, and VCLF groups, a decrease in blood glucose levels was observed. Similar results regarding serum insulin and glucose levels at the end of the experiment were observed within groups. V. myrtillus extracts prevented the development of cataract compared with the DC group (P < .05).

Protective effect of Pterocarpus marsupium bark extracts against cataract through the inhibition of aldose reductase activity in streptozotocin-induced diabetic male albino rats.

The present study was aimed to investigate the protective effect of Pterocarpus marsupium bark extracts against cataract in streptozotocin-induced diabetic male albino rats. Aldose reductase is a key enzyme in the intracellular polyol pathway, which plays a major role in the development of diabetic cataract. Rats were divided into five groups as normal control, diabetic control, and diabetic control treated with different concentrations of Pterocarpus marsupium bark extracts. Presence of major constituents in Pterocarpus marsupium bark extract was performed by qualitative analysis. Body weight changes, blood glucose, blood insulin, and reduced glutathione (GSH) and aldose reductase mRNA and protein expression were determined. Rat body weight gain was noted following treatment with bark extracts. The blood glucose was reduced up to 36% following treatment with bark extracts. The blood insulin and tissue GSH contents were substantially increased more than 100% in diabetic rats following treatment with extracts. Aldose reductase activity was reduced up to 79.3% in diabetic rats following treatment with extracts. Vmax, Km, and Ki of aldose reductase were reduced in the lens tissue homogenate compared to the diabetic control. Aldose reductase mRNA and protein expression were reduced more than 50% following treatment with extracts. Treatment with Pterocarpus marsupium bark was able to normalize these levels. Taking all these data together, it is concluded that the use of Pterocarpus marsupium bark extracts could be the potential therapeutic approach for the reduction of aldose reductase against diabetic cataract.

The structural damages of lens crystallins induced by peroxynitrite and methylglyoxal, two causative players in diabetic complications and preventive role of lens antioxidant components

Peroxynitrite (PON) and methylglyoxal (MGO), two diabetes-associated compounds, are believed to be important causative players in development of diabetic cataracts. In the current study, different spectroscopic methods, gel electrophoresis, lens culture and microscopic assessments were applied to examine the impact of individual, subsequent or simultaneous modification of lens crystallins with MGO and PON on their structure, oligomerization and aggregation. The protein modifications were confirmed with detection of the significantly increased quantity of carbonyl groups and decreased levels of sulfhydryl, tyrosine and tryptophan. Also, lens proteins modification with these chemical agents was accompanied with important structural alteration, oligomerization, disulfide/chromophore mediated protein crosslinking and important proteolytic instability. All these structural damages were more pronounced when the lens proteins were modified in the presence of both mentioned chemical agents, either in sequential or simultaneous manner. Ascorbic acid and glutathione, as the main components of lens antioxidant defense mechanism, were also capable to markedly prevent the damaging effects of PON and MGO on lens crystallins, as indicated by gel electrophoresis. The results of this study may highlight the importance of lens antioxidant defense system in protection of crystallins against the structural insults induced by PON and MGO during chronic hyperglycemia in the diabetic patients.