Estrogen protects lenses against cataract induced by transforming growth factor-beta (TGFbeta)

Trends in the global burden of vision loss among the older adults from 1990 to 2019

Purpose

To quantify the global impact of vision impairment in individuals aged 65 years and older between 1990 and 2019, segmented by disease, age, and sociodemographic index (SDI).

Methods

Using the Global Burden of Diseases 2019 (GBD 2019) dataset, a retrospective demographic evaluation was undertaken to ascertain the magnitude of vision loss over this period. Metrics evaluated included case numbers, prevalence rates per 100,000 individuals, and shifts in prevalence rates via average annual percentage changes (AAPCs) and years lived with disability (YLDs).

Results

From 1990 to 2019, vision impairment rates for individuals aged 65 years and older increased from 40,027.0 (95% UI: 32,232.9-49,945.1) to 40,965.8 (95% UI: 32,911-51,358.3, AAPC: 0.11). YLDs associated with vision loss saw a significant decrease, moving from 1713.5 (95% UI: 1216.2-2339.7) to 1579.1 (95% UI: 1108.3-2168.9, AAPC: -0.12). Gender-based evaluation showed males had lower global prevalence and YLD rates compared to females. Cataracts and near vision impairment were the major factors, raising prevalence by 6.95 and 2.11%, respectively. Cataract prevalence in high-middle SDI regions and near vision deficits in high SDI regions significantly influenced YLDs variation between 1990 and 2019.

Conclusion

Over the past three decades, there has been a significant decrease in the vision impairment burden in individuals aged 65 and older worldwide. However, disparities continue, based on disease type, regional SDI, and age brackets. Enhancing eye care services, both in scope and quality, is crucial for reducing the global vision impairment burden among the older adults.

Association of Alpha-Crystallin with Human Cortical and Nuclear Lens Lipid Membrane Increases with the Grade of Cortical and Nuclear Cataract

Eye lens α-crystallin has been shown to become increasingly membrane-bound with age and cataract formation; however, to our knowledge, no studies have investigated the membrane interactions of α-crystallin throughout the development of cataracts in separated cortical membrane (CM) and nuclear membrane (NM) from single human lenses. In this study, four pairs of human lenses from age-matched male and female donors and one pair of male lenses ranging in age from 64 to 73 years old (yo) were obtained to investigate the interactions of α-crystallin with the NM and CM throughout the progression of cortical cataract (CC) and nuclear cataract (NC) using the electron paramagnetic resonance spin-labeling method. Donor health history information (diabetes, smoker, hypertension, radiation treatment), sex, and race were included in the data analysis. The right eye lenses CM and NM investigated were 64 yo male (CC: 0), 68 yo male (CC: 3, NC: 2), 73 yo male (CC: 1, NC: 2), 68 yo female (CC: 3, NC: 2), and 73 yo female (CC: 1, NC: 3). Similarly, left eye lenses CM and NM investigated were 64 yo male (CC: 0), 68 yo male (CC: 3, NC: 2), 73 yo male (CC: 2, NC: 3), 68 yo female (CC: 3, NC: 2), and 73 yo female (CC: 1, NC: 3). Analysis of α-crystallin binding to male and female eye lens CM and NM revealed that the percentage of membrane surface occupied (MSO) by α-crystallin increases with increasing grade of CC and NC. The binding of α-crystallin resulted in decreased mobility, increased order, and increased hydrophobicity on the membrane surface in male and female eye lens CM and NM. CM mobility decreased with an increase in cataracts for both males and females, whereas the male lens NM mobility showed no significant change, while female lens NM showed increased mobility with an increase in cataract grade. Our data shows that a 68 yo female donor (long-term smoker, pre-diabetic, and hypertension; grade 3 CC) showed the largest MSO by α-crystallin in CM from both the left and right lens and had the most pronounced mobility changes relative to all other analyzed samples. The variation in cholesterol (Chol) content, size and amount of cholesterol bilayer domains (CBDs), and lipid composition in the CM and NM with age and cataract might result in a variation of membrane surface mobility, membrane surface hydrophobicity, and the interactions of α-crystallin at the surface of each CM and NM. These findings provide insight into the effect of decreased Chol content and the reduced size and amount of CBDs in the cataractous CM and NM with an increased binding of α-crystallin with increased CC and NC grade, which suggests that Chol and CBDs might be a key component in maintaining lens transparency.

Sex differences in symptom presentation and their impact on diagnostic accuracy in Werner syndrome

AIM

Whether sex differences exist in hereditary progeroid syndromes remains unclear. In this study, we investigated sex differences in patients with Werner syndrome (WS), a model of human aging, using patient data at the time of diagnosis.

METHODS

The presence of six cardinal signs in the diagnostic criteria was retrospectively evaluated.

RESULTS

We found that the percentage of patients with all cardinal signs was higher in males than in females (54.2% vs. 21.2%). By the age of 40 years, 57.1% of male patients with WS presented with all the cardinal signs, whereas none of the female patients developed all of them. In particular, the frequency of having a high-pitched, hoarse voice, a characteristic of WS, was lower in female patients. The positive and negative predictive values for clinical diagnosis were 100% for males and females, indicating the helpfulness of diagnostic criteria regardless of sex. More female patients than male (86.7% vs. 64%) required genetic testing for their diagnosis because their clinical symptoms were insufficient, suggesting the importance of genetic testing for females even if they do not show typical symptoms of WS. Finally, the frequency of abnormal voice was lower in patients with WS harboring the c.3139-1G > C homozygous mutation.

CONCLUSION

These results indicate, for the first time, that there are sex differences in the phenotypes of hereditary progeroid syndromes. The analysis of this mechanism in this human model of aging may lead to the elucidation of sex differences in the various symptoms of normal human aging. Geriatr Gerontol Int 2024; 24: 161-167.

Hysterectomy for Benign Indications and Risk of Cataract Formation in South Korean Women

Background and Objectives: Few studies have investigated the relationship between female reproductive hormones, especially estrogen, and the incidence of cataracts. This study sought to evaluate the effects of hysterectomy on the risk of lens opacity in Korean women. Materials and Methods: This retrospective cohort study utilized data collected from 2007 to 2020 for 255,576 postmenopausal women in the Korean National Health Insurance database. Participants were divided into those who did and did not undergo hysterectomy. The hysterectomy group was further divided into two subgroups according to the type of adnexal surgery performed. The prevalence of cataracts was then compared among the control, hysterectomy alone, and hysterectomy with adnexal surgery groups. Results: The control group included 137,999 participants who did not undergo hysterectomy, while the treatment group included 93,719 women who underwent hysterectomy alone or in combination with adnexal surgery. The incidence of cataracts was higher in the control group than in the treatment group, as demonstrated in a 1:1 propensity score-matching analysis adjusted for potential confounding variables. Conclusions: The incidence of cataracts was significantly lower in the group with hysterectomy than in the control group, but the difference was subtle. The current findings may aid in identifying the role of female reproductive hormones in cataract development.

Menopausal hormone therapy and the risk of cataracts in postmenopausal women in South Korea

PURPOSE

Postmenopausal women have a higher prevalence of cataracts than men of a similar age. This study aimed to evaluate the effects of menopausal hormone therapy (MHT) on lens opacities in postmenopausal women.

METHODS

This retrospective cohort study analysed population-based health insurance data in South Korea collected from 2002 to 2019. To determine the risk factors associated with cataract, postmenopausal women (N = 2,506,271) were grouped according to post-MHT use. The treatment group was further divided into the following subgroups: tibolone, combined oestrogen plus progestin by manufacturer, oral oestrogen, combined oestrogen plus progestin by physician and topical oestrogen groups. The main outcome measure was the prevalence of cataracts.

RESULTS

The control group comprised 463,151 postmenopausal women who had never used MHT after menopause, while the treatment group included 228,033 postmenopausal women who had used MHT continuously for at least 6 months. The treatment group had a higher incidence of cataracts than the control group based on Cox proportional hazards ratio analysis. Low socioeconomic status and high parity were identified as risk factors for cataracts, and reduced risk of cataracts was associated with living in rural areas and drinking alcohol.

CONCLUSIONS

Women undergoing post-MHT, including tibolone, had a higher incidence of cataracts. Cataract development should be a concern when examining postmenopausal patients using MHT.

Evaluation of Systemic Medications Associated With Surgically Treated Cataract Among US Adults

PURPOSE

To comprehensively determine the associations between systemic medications and surgically treated cataract in the US population.

DESIGNS

Retrospective cross-sectional study.

METHODS

Participants aged ≥40 years from the 1999-2008 National Health and Nutrition Examination Survey (NHANES) were included. Surgically treated cataract was defined as cataract requiring a procedure. Data on prescription drug use over the past 30 days were collected via home interviews. Drug categories for ophthalmic indications and those prescribed in less than 0.5% of the participants were excluded from the analysis. Separate logistic regression models were used to explore associations between each drug category and surgically treated cataract. The Benjamin-Hochberg procedure was used to control the false discovery rate.

RESULTS

A total of 14,931 were included in the present analysis. The weighted prevalence of surgically treated cataract was 9.6% (n=2010). We identified 20 drug categories that had significant associations with surgically treated cataract, of which 8 associations remained statistically significant after further adjustment for pertinent comorbidities. The 3 drug categories with the highest odds ratio (OR) values were tricyclic antidepressants (OR, 2.21; 95% CI, 1.38-3.51; P = .001), insulin (OR, 2.13; 95% CI, 1.48-3.07; P = 9.41×10^-5) and group III antiarrhythmic agents (OR, 2.00; 95% CI, 1.25-3.19; P = .004). The use of sex hormone combinations among women reduced the risk of having surgically treated cataract (OR, 0.011; 95% CI, 0.001-0.089; P = 5.98×10^-5). Dose-response relationships were observed for all 8 drug categories.

CONCLUSIONS

Our comprehensive evaluation provides new knowledge on the complex relationships between systemic medications and surgically treated cataract.

Sex Hormones and Their Effects on Ocular Disorders and Pathophysiology: Current Aspects and Our Experience

Sex hormones are molecules produced by the gonads and to a small extent by the adrenal gland, which not only determine the primary and secondary sexual characteristics of an individual, differentiating man from woman, but also participate in the functioning of the various systems of the body. The evidence that many eye diseases differ in terms of prevalence between men and women has allowed us, in recent years, to carry out several studies that have investigated the association between sex hormones and the pathophysiology of eye tissues. Specific receptors for sex hormones have been found on the lacrimal and meibomian glands, conjunctiva, cornea, lens, retina, and choroid. This work summarizes the current knowledge on the role that sex hormones play in the pathogenesis of the most common ocular disorders and indicates our clinical experience in these situations. The aim is to stimulate an interdisciplinary approach between endocrinology, neurology, molecular biology, and ophthalmology to improve the management of these diseases and to lay the foundations for new therapeutic strategies.

Utilizing Data Mining Algorithms and Geospatial Analysis to Study Cataract Surgeries in Florida

Purpose

To determine statewide cataract surgery rates with cataract extraction with intraocular lens implantation (CEIOL) in Florida from 2005 to 2014 among Caucasians, African-Americans, Hispanics, and Asian/Pacific Islanders.

Methods

This is a retrospective database study analyzing ambulatory surgical data in Florida from 2005 to 2014. Using the Agency for Healthcare Research and Quality's Healthcare Cost and Utilization Project (HCUP) and State Ambulatory Surgery and Services Databases (SASD), the authors utilized data mining algorithms to analyze and graphically represent disparities in the delivery of cataract surgery, changes in surgery volume, and demographic characteristics in patients 65 years and older in all Florida counties from 2005 to 2014.

Results

Cataract surgeries performed in patients ≥65 years of age represented 1,892,132 (14.90%) of the 12,695,932 total ambulatory surgical procedures from 2005 to 2014 in the HCUP-SASD Florida database. More surgeries were performed in females versus males, P < 0.001. Caucasians, African-Americans, and Hispanics represented 82.23%, 4.95%, and 10.69% of the utilization rate of all CEIOLs, respectively. From 2005 to 2014, the average surgery volume increased by an average rate of change of 1.29%. Cataract surgery penetration in the general population observed a steady decrease from 18.82% in 2005 to 16.66% in 2014.

Conclusions

Cataract surgery in Florida exhibited an unequal distribution with respect to gender and race, and select counties exhibited marked changes in surgical volume over the past 11 years. This study establishes a method for data mining and geospatial analysis to study surgical and epidemiological trends and identify disparities in delivery of healthcare.

The Protective Effect of Estrogen Against Radiation Cataractogenesis is Dependent Upon the Type of Radiation

Astronauts participating in prolonged space missions constitute a population of individuals who are at an increased risk for cataractogenesis due to exposure to densely ionizing charged particles. Using a rat model, we have previously shown that after irradiation of eyes with either low-linear energy transfer (LET) 60Co γ rays or high-LET 56Fe particles, the rate of progression of anterior and posterior subcapsular cataracts was significantly greater in ovariectomized females implanted with 17-β-estradiol (E2) compared to ovariectomized or intact rats. However, our additional low-LET studies indicated that cataractogenesis may be a modifiable late effect, since we have shown that the modulation of cataractogenesis is dependent upon the timing of administration of E2. Interestingly, we found that E2 protected against cataractogenesis induced by low-LET radiation, but only if administered after the exposure; if administered prior to and after irradiation, for the entire period of observation, then E2 enhanced progression and incidence of cataracts. Since most radioprotectors tested to date are unsuccessful in protecting against the effects of high-LET radiation, we wished to determine whether the protection mediated by E2 against radiation cataractogenesis induced by low-LET radiation would also be observed after high-LET irradiation. Female 56-day-old Sprague-Dawley rats were treated with E2 at various times relative to the time of single-eye irradiation with 2 Gy of 56Fe ions. We found that administration of E2 before irradiation and throughout the lifetime of the rat enhanced cataractogenesis compared to ovariectomized animals. The enhancing effect was slightly reduced when estrogen was removed after irradiation. However, in contrast to what we observed after γ-ray irradiation, there was no inhibition of cataractogenesis if E2 was administered only after 56Fe-ion irradiation. We conclude that protection against cataractogenesis by estrogen is dependent upon the type and ionization density of radiation that the lens was exposed to. The lack of inhibition of radiation cataractogenesis in rats that receive E2 treatment after high-LET irradiation may be attributed to the qualitative differences in the types of DNA damage induced with high-LET radiation compared to low-LET radiation or how damage may be modified at the DNA or tissue level after irradiation.

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.

A Rat Eye Lens Model of Cataract Formation

This chapter describes the use of lenses obtained from rats as a model of cataractogenesis. At the molecular level, this is visualized as reduced activity of oxidative reductive enzymes such as aldose reductase and increased proteolysis of lens structural proteins including vimentin. In this chapter, protocols for assessment of these two pathways are presented. Specifically, this analysis shows a comparison of aldose reductase activity and vimentin cleavage in male and female rat lenses. This is because female rats are more susceptible to cataract formation compared to males.

Effects of 17β-Estradiol on Activity, Gene and Protein Expression of Superoxide Dismutases in Primary Cultured Human Lens Epithelial Cells

PURPOSE

Protective effects of estradiol against H₂O₂-induced oxidative stress have been demonstrated in lens epithelial cells. The purpose of this study was to investigate the effects of 17β-estradiol (E2) on the different superoxide dismutase (SOD) isoenzymes, SOD-1, SOD-2, and SOD-3, as well as estrogen receptors (ERs), ERα and ERβ, in primary cultured human lens epithelial cells (HLECs).

MATERIALS AND METHODS

HLECs were exposed to 0.1 µM or 1 µM E2 for 1.5 h and 24 h after which the effects were studied. Protein expression and immunolocalization of SOD-1, SOD-2, ERα, and ERβ were studied with Western blot and immunocytochemistry. Total SOD activity was measured, and gene expression analyses were performed for SOD1, SOD2, and SOD3.

RESULTS

Increased SOD activity was seen after 1.5 h exposure to both 0.1 µM and 1 µM E2. There were no significant changes in protein or gene expression of the different SODs. Immunolabeling of SOD-1 was evident in the cytosol and nucleus; whereas, SOD-2 was localized in the mitochondria. Both ERα and ERβ were immunolocalized to the nucleus, and mitochondrial localization of ERβ was evident by colocalization with MitoTracker. Both ERα and ERβ showed altered protein expression levels after exposure to E2.

CONCLUSIONS

The observed increase in SOD activity after exposure to E2 without accompanying increase in gene or protein expression supports a role for E2 in protection against oxidative stress mediated through non-genomic mechanisms.

2D-DIGE Analysis of Eye Lens Proteins as a Measure of Cataract Formation

This chapter describes the basics of two-dimensional difference gel electrophoresis (2D-DIGE) for multiplex analysis of two distinct proteomes. The example given describes the analysis of male and female rat lens soluble proteins labeled with fluorescent Cy3 and Cy5 dyes in comparison to a pooled standard labeled with Cy2. After labeling the proteomes are mixed together and electrophoresed on the same 2D gels. Scanning the gels at wavelengths specific for each dye allows direct overlay the two different proteomes. Differences in abundance of specific protein spots can be determined through comparison to the pooled standard.

Letrozole induced low estrogen levels affected the expressions of duodenal and renal calcium-processing gene in laying hens

Estrogen regulates the calcium homeostasis in hens, but the mechanisms involved are still unclear fully. In this study, we investigated whether letrozole (LZ) induced low estrogen levels affected the calcium absorption and transport in layers. In the duodenum, we observed a significant decrease of mRNA expressions of Calbindin-28k (CaBP-28k) and plasma membrane Ca²⁺-ATPase (PMCA 1b) while CaBP-28k protein expression was declined in birds with LZ treatment, and the mRNA levels of duodenal transient receptor potential vanilloid 6 (TRPV6) and Na⁺/Ca²⁺ exchanger 1 (NCX1) were not affected. Interestingly, we observed the different changes in the kidney. The renal mRNA expressions of TRPV6 and NCX1 were unregulated while the PMCA1b was down-regulated in low estrogen layers, however, the CaBP-28k gene and protein expressions were no changed in the kidney. Furthermore, it showed that the duodenal estradiol receptor 2 (ESR2) transcripts rather than parathyroid hormone 1 receptor (PTH1R) and calcitonin receptor (CALCR) played key roles to down-regulate calcium transport in LZ-treated birds. In conclusion, CaBP-28k, PMCA 1b and ESR2 genes in the duodenum may be primary targets for estrogen regulation in order to control calcium homeostasis in hens.

Protective Effects of 17β-Estradiol on Benzo(e) pyrene[B(e)P]-induced Toxicity in ARPE-19 cells

Purpose:

The aim of this study was to examine the effect of 17β-estradiol on Benzo(e)pyrene [B(e)P]-induced toxicity in ARPE-19 cells.

Methods:

We pretreated ARPE-19 cells with 20 nM and 40 nM 17β-estradiol for 6 hours, followed by addition of 300 μM B(e)P for additional 24 hours. Cell viability was measured using Trypan blue dye-exclusion assay. JC-1 assay was performed to measure mitochondrial membrane potential (ΔΨm). For a quantitative estimation of cell death, apoptotic markers such as caspase-3/7, caspase-9, and caspase-12 were measured.

Results:

Our results demonstrated that when treated with B(e)P, the viability and ΔΨm of ARPE-19 cells declined by 25% and 63%, respectively (P < 0.05). However, pretreating with 17β-estradiol increased the viability of ARPE-19 cells by 21% (20 nM) and 10% (40 nM) (P < 0.05). Furthermore, the significantly reduced ΔΨm in βE+B(e)P treated cells ARPE-19 cells was restored by pre-treatment with 17β-estradiol- ΔΨm was increased by 177% (20 nM) and 158% (40 nM) (P < 0.05). We further observed a significant up-regulation in the activity of Caspases-3/7, -9, and -12 in B(e)P-treated ARPE-19 cells. However, 17β-estradiol treatment significantly reduced the activity of all apoptotic markers (P < 0.05).

Conclusion:

In conclusion, our results demonstrate that 17β-estradiol protects ARPE-19 cells against B(e)P-induced toxicity by decreasing apoptosis, preventing cell death, and restoring mitochondrial membrane potential.

Timing of first childbirth and age-related cataract

OBJECTIVE

No studies investigated the effects of age at first childbirth on cataract formation. This study was performed to determine the relationships of age at first childbirth to age-related cataract in postmenopausal women.

METHODS

Study population included 7,021 postmenopausal women in the Korea National Health and Nutrition Examination Survey, 2008 to 2012. Participants were subdivided in quartiles according to the age at first childbirth as follows: 13 to 21, 22 to 23, 24 to 25, and 26 to 44 years. We used odds ratios (ORs) and 95% confidence intervals (CIs) to address the relationships between age at first childbirth and age-related cataract with adjustments for confounders.

RESULTS

Mean participants' age and age at first childbirth were 64.4 and 23.6 years, respectively. The prevalence of any subtype of age-related cataract was 64.9%. Nuclear cataract prevalence was significantly higher in postmenopausal women with later age at first childbirth (24-25 and 26-44 years) compared with those with the earliest age at first childbirth (13-21 years): ORs (95% CIs) were 1.23 (1.05-1.45) and 1.24 (1.05-1.46), respectively. A significant linear trend across quintile was observed (P = 0.006). Age at first childbirth linearly 4% (OR 1.04, 95% CI 1.01-1.06) and 2% (OR 1.02, 95% CI 1.00-1.04) increased risk for nuclear and cortical cataract formation, respectively. The population-attributable fraction of nuclear cataract caused by the first childbirth at 24 years or later was 4.9% (95% CI 1.20%-8.59%, P = 0.009).

CONCLUSIONS

Later age of first childbirth was independently associated with higher risks of nuclear and cortical cataract in postmenopausal women. Further prospective studies are needed to elucidate the role of age at first childbirth in developing age-related cataract.

Efficacy of Intravitreal injection of 2-Methoxyestradiol in regression of neovascularization of a retinopathy of prematurity rat model

Background

Retinopathy of prematurity (ROP) is one of the targets for early detection and treatment to prevent childhood blindness in world health organization programs. The purpose of study was to evaluate the efficacy of intravitreal injection of 2-Methoxyestradiol (2-ME) nanoemulsion in regressing neovascularization of a ROP rat model.

Methods

A prospective comparative case - control animal study conducted on 56 eyes of 28 healthy new born Sprague Dawley male albino rat. ROP was induced in 21 rats then two concentrations of 2-ME nanoparticles were injected in right eyes of 14 rats (low dose; study group I, high dose; study group II). A blank nanoemulsion was injected in the right eyes of seven rats (control positive group I). No injections performed in contralateral left eyes (control positive group II). Seven rats (14 eyes) were kept in room air (control negative group). On postnatal day 17, eyeballs were enucleated. Histological structure of the retina was examined using Hematoxylin and eosin staining. Vascular endothelial growth factor (VEGF) and glial fibrillary acidic protein (GFAP) expressions were detected by immunohistochemical studies.

Results

Intravitreal injection of 2-ME (in the two concentrations) caused marked regression of the new vascular tufts on the vitreal side with normal organization and thickness of the retina especially in study group II, which also show negative VEGF immunoreaction. Positive GFAP expression was detected in the control positive groups and study group (I).

Conclusion

Intravitreal injection of 2-Methoxyestradiol nanoemulsion is a promising effective method in reduction of neovascularization of a ROP rat model.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-017-0433-3) contains supplementary material, which is available to authorized users.

Development of topical ophthalmic In Situ gel-forming estradiol delivery system intended for the prevention of age-related cataracts

The goal of this study was to develop and characterize an ion-activated in situ gel-forming estradiol (E2) solution eye drops intended for the prevention of age-related cataracts. Accordingly, in situ gelling eye drops were made using gellan gum as an ion-activated gel-forming polymer, polysorbate-80 as drug solubilizing agent, mannitol as tonicity agent, and combination of potassium sorbate and edetate disodium dihydrate (EDTA) as preservatives. The formulations were tested for the following characteristics: pH, clarity, osmolality, antimicrobial efficacy, rheological behavior, and in vitro drug release. Stability of the formulation was also monitored for 6 months at multiple storage conditions per ICH Q1A (R2) guidelines. The solution eye drops resulted in an in-situ phase change to gel-state when mixed with simulated tear fluid (STF). The gel structure formation was confirmed by viscoelastic measurements. Drug release from the gel followed non-fickian mechanism with 80% of drug released in 8 hr. The formulations were found to be clear, isotonic with suitable pH and viscoelastic behavior and stable at accelerated and long-term storage conditions for 6 months. In vitro results suggest that the developed formulation is suitable for further investigation in animal models to elucidate the ability of estrogen to prevent and delay cataracts.

Relationship between Reproductive Exposures and Age-Related Cataract in Women

The objective of this study is to evaluate the relationship between reproductive exposures and age-related cataract among women. This was a hospital based case-control study. The study population included female patients, aged 50 years and above who attended the Eye clinic at the University of Malaya Medical Centre. The outcome measurement was based on ophthalmologic examination by an ophthalmologist. The data on exposure was obtained from face to face interview using a structured questionnaire. In order to reduce the recall bias, patients' medical records were used to substantiate the exposure status. Multiple logistic regression was used to assess the association of age-related cataract with exogenous estrogen usage (HRT and OCP) and duration of menses. Important confounders such as age, history of diabetes, cigarette smoking and steroids usage were controlled for in the analysis. Females with 29 years or less of endogenous estrogen exposure of, have almost three times the risk of developing age related cataract (adjusted OR 3.42: 95% CI: 1.28,9.16), similarly among those with exposure of 30- 32 years (adjusted OR 3.64: 95% CI: 1.08,12.26). Hormone Replacement Therapy used for more than three years was found to be a protective factor of age-related cataract. There is evidence that reproductive exposure may play a role in reducing the occurrence of age-related cataract among Malaysian women. Asia Pac J Public Health 2007; 19(2): 23-28.

Cataracts

Cataract surgery with an intraocular lens implant is one of the most common and thought to be the most effective surgical procedure in any field of medicine. Although aging is the most common cause, other factors are also known to be associated with cataract formation. Although cataracts are the domain of ophthalmology, primary care physicians are frequently the ones to whom patients present with vision complaints. Knowledge of cataract symptoms, how to evaluate them, and a basic understanding of the surgery to correct cataracts make primary care physicians an integral part of treating this leading cause of preventable blindness.

Increased Expression of Interleukin-18 in Lenses of Ovariectomized Rats

Previous studies showed an increased prevalence of cataracts in postmenopausal women. In this study, we investigated changes in the levels of calcium ion (Ca(2+)) and interleukin (IL)-18, which are factors in cataract development, in the lenses of ovariectomized (OVX) rats, a model of postmenopausal woman. Although the Ca(2+) content in the blood of OVX rats increased 1 month after ovariectomy and subsequently decreased, the Ca(2+) content in the lenses was unchanged in OVX rats 1-3 months after ovariectomy. The Ca(2+)-ATPase activity in the lenses of OVX rats peaked 1 month after ovariectomy, and the behavior of Ca(2+)-ATPase activity in lenses of OVX rats was similar to that of the Ca(2+) concentration in the blood. It is possible that hypercalcemia increases the Ca(2+) inflow into the lens; however, the enhanced Ca(2+)-ATPase activity prevents the Ca(2+) level from rising. On the other hand, we found that the levels of both IL-18 and interferon (IFN)-γ in the lenses of OVX rats were significantly increased as compared with the lenses of sham (control) rats during the period 1-3 months after surgery. These results suggest that the expression of IFN-γ via IL-18 in the lenses of OVX rats is induced by ovariectomy, and that excessive IL-18 and IFN-γ production in the lenses may be related to cataract development in postmenopausal women. These findings support those of previous studies that assessed lens opacification in postmenopausal women.

Oestrogen, ocular function and low-level vision: a review

Over the past 10 years, a literature has emerged concerning the sex steroid hormone oestrogen and its role in human vision. Herein, we review evidence that oestrogen (oestradiol) levels may significantly affect ocular function and low-level vision, particularly in older females. In doing so, we have examined a number of vision-related disorders including dry eye, cataract, increased intraocular pressure, glaucoma, age-related macular degeneration and Leber's hereditary optic neuropathy. In each case, we have found oestrogen, or lack thereof, to have a role. We have also included discussion of how oestrogen-related pharmacological treatments for menopause and breast cancer can impact the pathology of the eye and a number of psychophysical aspects of vision. Finally, we have reviewed oestrogen's pharmacology and suggest potential mechanisms underlying its beneficial effects, with particular emphasis on anti-apoptotic and vascular effects.

The gender-differentiated antioxidant effects of a lutein-containing supplement in the aqueous humor of patients with senile cataracts

Antioxidant supplements are expected to decrease oxidative damage and prevent ocular diseases. In this study, changes in the anti-oxidative ability and oxidative status in the aqueous humor before and after intake of a lutein-containing supplement were measured. Forty patients who all had identical grades of cataracts in both eyes were included. The aqueous humor was collected as pre-intake samples during cataract surgery. Ocuvite + Lutein(Ⓡ), an antioxidant supplement, was administered orally beginning the day after surgery. Six weeks later, the aqueous humor was collected as a post-intake sample during cataract surgery of the opposite eye. To determine the anti-oxidative ability, the levels of superoxide (O2(*-)) scavenging activity were measured. To determine the oxidative status, the levels of hydrogen peroxide (H2O2) and total amount of hydroperoxides (TH, including H2O2 and peroxides of lipids, proteins, and nucleic acids) were measured. In post-intake samples, the O2(*-) scavenging activities were significantly higher in both genders (p < 0.05). The levels of H2O2 were significantly higher (p < 0.01) while the levels of TH were significantly lower (p < 0.01) only in females. The level of H2O2 was significantly negatively correlated to the TH in the post-intake samples of both genders (r = -0.50 and p < 0.05 for males; r = -0.59 and p < 0.01 for females) while the level of H2O2 was significantly positively correlated to the O2(*-) scavenging activity in both pre- and post-intake aqueous humor in females only (r = 0.66 and p < 0.01 for pre-intake samples, r = 0.71 and p < 0.01 for post-intake samples). After the introduction of the antioxidant supplement, O2(*-) scavenging activity increased while H2O2 levels remained the same in males, suggesting that scavenging rates are proportional. In postmenopausal females, the superoxide scavenging activity also increased, however unlike in males, the H2O2 levels also increased meaning H2O2 was not completely scavenged. H2O2 is a non-free radical and can be excreted from the aqueous humor to prevent further oxidation of lipids, proteins, and nucleic acids, which was confirmed by the low levels of TH in post-intake samples. Antioxidant supplements are suggested to be effective in reducing oxidation in the aqueous humor by different mechanisms in both genders.

Gender and cataract--the role of estrogen

There is evidence from epidemiologic data that cataract is more common in women than men. This is not solely due to a higher rate of cataract extraction in women, as is the case in the western world, but several population-based studies show that females have a higher prevalence of lens opacities, especially cortical. There is no firm evidence that lifestyle-related factors are the cause of this gender discrepancy. Focus has therefore been directed towards the role of estrogen in cataract formation. Although data on endogenous and exogenous estrogen involvement in cataractogenesis are conflicting, some studies have indicated that hormone therapy may decrease the risk of cataract and thus be protective. It has been hypothesized that the decrease in estrogen at menopause cause increased risk of cataract in women, i.e. not strictly the concentration of estrogen, but more the withdrawal effect. Estrogens are known to exert several anti-aging effects that may explain the longer lifespan in women, including metabolically beneficial effects, neuroprotection, preservation of telomeres and anti-oxidative properties. Since oxidative stress is considered important in cataractogenesis, studies have investigated the effects of estrogens on lens epithelial cells in culture or in animal models. Several investigators have found protection by physiological concentrations of 17β-estradiol against oxidative stress induced by H2O2 in cultured lens epithelial cells. Although both main types of estrogen receptors, ERα and ERβ, have been demonstrated in lens epithelium, most studies so far indicate that the estrogen-mediated protection in the lens is exerted through non-genomic, i.e. receptor-independent mechanisms, possibly through phosphorylation of extracellular signal-regulated kinase (ERK1/ERK2), a member of the mitogen-activated protein kinase (MAPK)-signaling pathway. Further studies are needed, both epidemiologic as to the role of hormone therapies, and laboratory studies regarding molecular estrogen-mediated mechanisms, in order to comprehend the role of estrogens on cataract formation.

The lens equator: a platform for molecular machinery that regulates the switch from cell proliferation to differentiation in the vertebrate lens

The vertebrate lens is a transparent, spheroidal tissue, located in the anterior region of the eye that focuses visual images on the retina. During development, surface ectoderm associated with the neural retina invaginates to form the lens vesicle. Cells in the posterior half of the lens vesicle differentiate into primary lens fiber cells, which form the lens fiber core, while cells in the anterior half maintain a proliferative state as a monolayer lens epithelium. After formation of the primary fiber core, lens epithelial cells start to differentiate into lens fiber cells at the interface between the lens epithelium and the primary lens fiber core, which is called the equator. Differentiating lens fiber cells elongate and cover the old lens fiber core, resulting in growth of the lens during development. Thus, lens fiber differentiation is spatially regulated and the equator functions as a platform that regulates the switch from cell proliferation to cell differentiation. Since the 1970s, the mechanism underlying lens fiber cell differentiation has been intensively studied, and several regulatory factors that regulate lens fiber cell differentiation have been identified. In this review, we focus on the lens equator, where these regulatory factors crosstalk and cooperate to regulate lens fiber differentiation. Normally, lens epithelial cells must pass through the equator to start lens fiber differentiation. However, there are reports that when the lens epithelium structure is collapsed, lens fiber cell differentiation occurs without passing the equator. We also discuss a possible mechanism that represses lens fiber cell differentiation in lens epithelium.

The effects of postmenopausal hormone use on cataract: a meta-analysis

BACKGROUND

Cataract is the leading cause of blindness worldwide. Many observational studies assessed the relationship between postmenopausal hormone replacement therapy (HRT) and risk of cataract development, but the reported results were controversial. The aim of present meta-analysis was to evaluate the association of postmenopausal hormone replacement therapy with risk of cataract development.

METHODS

The eligible observational studies, including cross-sectional, case-control and cohort studies, were identified by searching PubMed and Embase during March of 2013. Either a fixed- or a random-effects model was used to calculate the pooled odds ratio (OR) with its 95% confidence interval (95%CI). Subgroup analysis on cataract types was performed.

RESULTS

A total of four cohort and five case-control or cross-sectional studies were finally included into this meta-analysis. Overall, a significant decreased risk of developing any type of cataract was found in ever HRT group as compared with non-HRT group among cohort studies (OR 0.83; 95%CI: 0.71,0.97) and case-control or cross-sectional studies (OR 0.74; 95%CI: 0.59,0.93). Subgroup analysis on cataract types determined that the significantly decreased risk of nuclear cataract in current HRT group (OR 0.72; 95%CI: 0.61,0.85) and also a critically reduced risk of nuclear cataract in ever HRT group (OR 0.80; 95% CI: 0.64,1.01) were found among case-control or cross-sectional studies, as compared with non-HRT group. No association of HRT with risk of cortical and posterior subcapsular cataract was observed.

CONCLUSIONS

The results of present meta-analysis indicate that postmenopausal hormone use may play a protective role in cataract development.

High affinity nuclear and nongenomic estradiol binding sites in the human and mouse lens

Estrogen is reported to be protective against cataracts in women and animal models. Immunodetection methods have identified the classic estrogen receptors (ER), ERα and ERβ, in human lens epithelial cells and their RNAs have been detected in the rat and human lens. To verify that estrogen binding occurs in the lens, sensitive [(125)I]-17β-estradiol binding analyses were performed on subcellular lens fractions from women (ages 39-78 years). The presence of high affinity estradiol binding sites in the nuclear, cytoplasmic, and membrane fractions indicate the lens is able to respond to estrogens, even up to age 78, although fewer binding sites were detected in the postmenopausal women. Additionally, due to the importance of mouse models in estrogen action and lens research, lenses from intact female mice were also analyzed. Both the C57BL/6 and FVB/N mouse strains also possessed high affinity binding sites in all three lens fractions. Furthermore, transcripts for ERα, ERβ, and G protein-coupled estrogen receptor (GPER; previously called GPR30) that bind estradiol with high affinity were expressed in the human and mouse lenses. These data provide the first evidence of GPER expression in the lens. Its role, functions, and subcellular location are currently unknown, but a G-shift assay in the membrane fractions of human and mouse lenses did not show evidence that estradiol induced classic G protein-coupled receptor activation. All three receptor transcripts were also detected in the lens capsule region isolated from female C57BL/6 mice, which is mainly comprised of epithelial cells. In contrast, only ERα and GPER were expressed in the cortex/nuclear region, which is primarily composed of differentiating and organelle-free fiber cells. No significant differences in specific estradiol binding and receptor RNA expression were observed in the lenses between male and female C57BL/6 mice. These findings indicate that the lens is an estrogen target tissue in both sexes. The identification of GPER, in addition to ERα and ERβ, in the lens also adds to the complexity of possible estrogen responses in the lens. Accordingly, the protective effects of estrogen in women and animals may be mediated by all three estrogen receptors in the lens. In addition, the similarities in binding and receptor RNA expression in the lenses of both species suggest that mice can be used to model estrogen action in the human lens.

Estrogen mediated protection of cytoskeleton against oxidative stress

BACKGROUND & OBJECTIVES

Cytoskeletal proteins are deregulated during oxidative stress and cataract formation. However, estrogen which protects against cataract formation and harmful effects of oxidative stress has not been tested on the cytoskeleton of lens epithelial cells (LECs). The current study was undertaken to assess if the protection rendered to LECs by estrogen was mediated by preserving the cytoskeletal proteins.

METHODS

Oxidative stress was induced by 50 μM of H 2 O 2 in cultured goat LECs (gLECs) and effect of 1 μM 17β-estradiol (E 2 ) was tested. After treatment, morphological analysis of cells was carried out using haematoxylin-eosin staining and cell density was also quantified. Cell viability was determined using Hoechst (Ho), YO-Pro (YP) and propidium iodide (PI). F-actin and vimentin were localized using phalloidin and anti-vimentin antibody, respectively, and viewed under fluorescence microscopy. Vimentin was further analysed at protein level by Western blotting.

RESULTS

H 2 O 2 led to increased condensation of nucleus, cell death and apoptosis but these were prevented with pre- and co-treatment of E 2 with increase in cell viability (P<0.001). E 2 also prevented H 2 O 2 mediated depolymerization of cytoskeleton but was not able to reverse the changes when given after induction of oxidative stress.

INTERPRETATION & CONCLUSIONS

Our findings showed that E 2 helped in preventing deteriorating effect of H 2 O 2 , inhibited cell death, apoptosis and depolymerisation of cytoskeletal proteins in LECs. However, the exact mechanism by which estrogen renders this protection to cytoskeleton of lens epithelial cells remains to be determined.

Lens opacities in Valencia, Spain

PURPOSE

To evaluate the most common lens opacities in Valencia (Spain), analyzed by gender, grade, and type of cataracts. The results are compared with other studies performed at other geographical latitudes and on different races.

METHODS

A total of 1951 eyes of patients diagnosed with cataracts, aged between 30 and 96 years, were evaluated in accordance with age, gender, type and degree of the cataract, bilaterality, and symmetry of this disease. Lens Opacities Classification System III was used to classify the cataract and the degree was graded as mild or moderate to advanced.

RESULTS

The most common type of cataract is corticonuclear in the elderly and subcapsular in younger subjects. The most common are nuclear (28.4%) followed by cortical (6.2%), if combined cataracts are ruled out. There is a greater incidence of cortical cataracts in women (70%) and subcapsular cataracts in men (70%).

CONCLUSIONS

The results suggest the existence of a gender factor in cataract formation and coincide with those obtained in similar studies performed in areas at a similar latitude (40º N) and with different race population. The geographical location (intensity and length of exposure to solar radiation) seems to be a determining factor in the formation of a specific type of cataract, more than race, although there are other factors that contribute in the formation of a specific type of cataract.

Mass spectrometry-based proteomics approaches applied in cataract research

Cataract, the opacification of the eye lens, is the leading cause of blindness worldwide--it accounts for approximately 42% of all cases. The lens fibers have the highest protein content within the body, more than 35% of their wet weight. Given the eye lens pure composition of highly abundant structural proteins crystallins (up to 90%), it seems to be an ideal proteomic entity to study and might be also hypothesized to model the other protein conformational diseases. Crystallins are extremely long-lived, and there is virtually no protein turnover. This provides great opportunities for post-translational modifications (PTM) to occur and to predispose lens to the cataract formation. Despite recent progress in proteomics, the human lens proteome remains largely unknown. Mass spectrometry hold great promise to determine which crystallin modifications lead to a cataract. Quantitative analysis of PTMs at the peptide level with proteomics is a powerful bioanalytical tool for lens-tissue samples, and provides more comprehensive results. New mass spectrometry-based approaches that are being applied to lens research will be highlighted. Finally, the future directions of proteomics cataract research will be outlined.

Risk of cataract and glaucoma in patients with multiple sclerosis

BACKGROUND

The aim of the study was to evaluate whether multiple sclerosis (MS) is associated with risk of cataract or glaucoma.

METHODS

We conducted a population-based cohort study utilizing the UK General Practice Research Database (1987-2009) linked to the national hospital registry of England (1997-2008). Incident MS patients (5576 cases) were identified and each was matched to six patients without MS (controls) by age, gender, and practice. Cox proportional hazard models were used to estimate hazard ratios (HRs) of incident cataract and glaucoma in MS. Time-dependent adjustments were made for age, history of diseases and drug use.

RESULTS

MS patients had no overall increased risk of cataract, adjusted (adj.) HR 1.15 (95% CI 0.94-1.41) or glaucoma, adj. HR 1.02 (95% CI 0.78-1.33). Risk of cataract (adj. HR 2.45 (95% CI 1.56-3.86)) and glaucoma (adj. HR 1.70 (95% CI 1.01-2.86)) was significantly greater in patients < 50 years, particularly in men < 50 years: cataract, adj. HR 4.23 (95% CI 2.22-8.05) and glaucoma, adj. HR 2.76 (95% CI 1.28-5.93).

CONCLUSION

This is the first study which showed that the risk of cataract and glaucoma is elevated in MS patients younger than 50 years, particularly men.

Effects of 17β-estradiol on proliferation, cell viability and intracellular redox status in native human lens epithelial cells

PURPOSE

The purpose of this study was to examine the effects of 17β-estradiol on proliferation, cell death and redox status in cultured human lens epithelial cells (HLECs).

METHODS

HLECs were exposed to 17β-estradiol after which cell viability was measured by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) and the number of mitotic and apoptotic cell nuclei was determined after staining with Hoechst 33342. Apoptosis was also determined by measuring caspase-3 activity and propidium iodide was used to determine the proportion of non-viable cells. Pro- and antioxidative effects of 17β-estradiol was investigated by measuring peroxides, superoxides and glutathione, using dichlorofluorescein diacetate (DCFH-DA), dihydroethidium (HET), and monochlorobimane (MCB), respectively. Effects on mitochondrial membrane potential were determined using 5,5',6,6'-tetrachloro-1,1',3,3'- tetraethylbenzimidazolylcarbocyanine iodide (JC-1). The ability of 17β-estradiol to prevent reactive oxygen species (ROS)-production in HLECs after exposure to 25 µM H₂O₂ for 24h was also measured.

RESULTS

This study demonstrates increased mitotic activity in HLECs exposed to physiologic concentrations of 17β-estradiol (1 nM). Pharmacological concentrations of 17β-estradiol caused increased number of apoptotic cell nuclei and caspase-3 activation. Physiologic concentrations of 17β-estradiol (0.1-10 nM) stabilized the mitochondrial membrane potential. Similar or slightly higher concentrations of 17β-estradiol (0.01-1 µM) protected against H₂O₂-induced oxidative stress as evident by decreased levels of peroxides and superoxides.

CONCLUSIONS

The present study demonstrates mitogenic and anti-oxidative effects of 17β-estradiol at physiologic concentrations, whereas pharmacological levels induced oxidative stress and acted pro-apoptotic in cultured lens cells.

Five-year incidence of age-related cataract and cataract surgery in the adult population of greater Beijing: the Beijing Eye Study

PURPOSE

To estimate the 5-year incidence of cataract and cataract surgery in an adult Chinese population.

DESIGN

Population-based study.

PARTICIPANTS

The Beijing Eye Study 2006 included 3251 (73.2%) subjects (≥45 years) of 4439 subjects who participated in the 2001 survey and returned for re-examination.

METHODS

Nuclear, cortical, and posterior subcapsular lens opacities were assessed based on standardized slit-lamp-based photographs and retroilluminated photographs of the lens using a modification of the grading score of the Age-Related Eye Disease Study.

MAIN OUTCOME MEASURES

Incidence of any type of cataract and of cataract surgery.

RESULTS

The 5-year incidence of nuclear cataract was 5.98% (95% confidence intervals [CI], 5.96%-6.00%), that of cortical cataract was 11.14% (95% CI, 11.12%-11.17%), that of posterior subcapsular cataract was 5.47% (95% CI, 5.45%-5.48%), and that of cataract surgery was 2.01% (95% CI, 2.00%-2.02%). The incidence of any cataract (16.82%; 95% CI, 16.79%-16.86%) was significantly associated with higher age (P<0.001) and female gender (P<0.001). It was not significantly associated with the area of habitation (P = 0.78), smoking (P = 0.95), or alcohol consumption (P = 0.12). Differentiation into the 3 cataract types revealed that the incidence of nuclear cataract additionally was associated with rural region (P<0.001) and smoking (P<0.001). The incidence of cortical cataract additionally was associated with nonsmoking (P = 0.02). The incidence of cataract surgery was significantly (P<0.001) associated with age only.

CONCLUSIONS

As in white persons, the age-adjusted incidence of all types of cataract types increased with age and it was associated with female gender. When compared with data in the literature, the incidence rates of all cataract types did not vary markedly between Chinese in greater Beijing and white persons. In contrast, the incidence of cataract surgery was considerably lower in this Chinese population.

Exogenous oestrogen exposure, female reproductive factors and the long-term incidence of cataract: the Blue Mountains Eye Study

PURPOSE

To assess the association between exogenous oestrogen exposure, female reproductive factors and the long-term incidence of cataract.

METHODS

People aged 49+ years living in a defined geographic region were invited to participate in this prospective population-based survey. Of 2072 women (83% of those eligible) who were examined during 1992-1994 at baseline, around 75% of survivors were re-examined at 5- and 10-year follow-up visits. Lens photographs were assessed using the Wisconsin Cataract Grading System by masked graders. An interviewer-administered questionnaire was used at each visit to collect information on female reproductive factors and the use of the oral contraceptive pill and postmenopausal hormone replacement therapy.

RESULTS

After adjusting for age, smoking, socioeconomic status, steroid use, hypertension and diabetes, ever having used the oral contraceptive pill had a mild protective effect against incident cortical cataract (odds ratio 0.70, 95% confidence interval 0.50-0.98). However, hormone replacement therapy, age at menarche, age at menopause, duration of exposure to endogenous oestrogen, parity and type of menopause were not found to have significant associations with the incidence of any type of cataract or cataract surgery.

CONCLUSION

Apart from a weak protective association of oral contraceptive pill use and the development of cortical cataract, we found no significant longitudinal associations between exogenous oestrogen exposure, female reproductive factors and the long-term incidence of cataract in this older population-based cohort.

Regulation of lens gap junctions by Transforming Growth Factor beta

Using cultured lens epithelial cells, we discovered a new type of cross-talk between the FGF and TGF-β pathways, as well as a novel role for TGF-β and p38 kinase in the regulation of gap junctional intercellular communication. Our findings provide an explanation for how pathologically increased TGF-β signaling could contribute to cataract formation.

Gap junction–mediated intercellular communication (GJIC) is essential for the proper function of many organs, including the lens. GJIC in lens epithelial cells is increased by FGF in a concentration-dependent process that has been linked to the intralenticular gradient of GJIC required for lens transparency. Unlike FGF, elevated levels of TGF-β are associated with lens dysfunction. We show that TGF–β1 or -2 up-regulates dye coupling in serum-free primary cultures of chick lens epithelial cells (dissociated cell-derived monolayer cultures [DCDMLs]) via a mechanism distinct from that utilized by other growth factors. Remarkably, the ability of TGF-β and of FGF to up-regulate GJIC is abolished if DCDMLs are simultaneously exposed to both factors despite undiminished cell–cell contact. This reduction in dye coupling is attributable to an inhibition of gap junction assembly. Connexin 45.6, 43, and 56–containing gap junctions are restored, and intercellular dye coupling is increased, if the activity of p38 kinase is blocked. Our data reveal a new type of cross-talk between the FGF and TGF-β pathways, as well as a novel role for TGF-β and p38 kinase in the regulation of GJIC. They also provide an explanation for how pathologically increased TGF-β signaling could contribute to cataract formation.

Effects of estrogen and gender on cataractogenesis induced by high-LET radiation

Planning for long-duration manned lunar and interplanetary missions requires an understanding of radiation-induced cataractogenesis. Previously, it was demonstrated that low-linear energy transfer (LET) irradiation with 10 Gy of (60)Co gamma rays resulted in an increased incidence of cataracts in male rats compared to female rats. This gender difference was not due to differences in estrogen, since male rats treated with the major secreted estrogen 17-beta-estradiol (E2) showed an identical increase compared to untreated males. We now compare the incidence and rate of progression of cataracts induced by high-LET radiation in male and female Sprague-Dawley rats. Rats received a single dose of 1 Gy of 600 MeV (56)Fe ions. Lens opacification was measured at 2-4-week intervals with a slit lamp. The incidence and rate of progression of radiation-induced cataracts was significantly increased in the animals in which estrogen was available from endogenous or exogenous sources. Male rats with E2 capsules implanted had significantly higher rates of progression compared to male rats with empty capsules implanted (P = 0.025) but not compared to the intact female rats. These results contrast with data obtained after low-LET irradiation and suggest the possibility that the different types of damage caused by high- and low-LET radiation may be influenced differentially by steroid sex hormones.

Effect of estrogen replacement therapy on lens epithelial cell apoptosis in an experimental rat model

Epidemiologic studies have revealed a higher incidence of cataracts in estrogen-deprived postmenopausal women, although the pathogenic mechanism has not yet been elucidated. Apoptosis of lens epithelial cells has been associated with cataractogenesis. The aim of the study reported here was to investigate the effect of estrogen replacement therapy (ERT) on lens epithelial cell apoptosis in an experimental rat model. Forty female Wistar rats were randomized into four groups: ERT (17beta-estradiol, 10 microg/kg/day) for 3 months without ovariectomy (group 1) and with ovariectomy (group 2); only ovariectomy (group 3); sham operated (group 4). At the end of the third month, all rats were sacrificed in estrous cycle, as determined by the vaginal smear test, and their right eyes were enucleated. Enucleated eyes were analyzed by immunohistochemical methods for the expression of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end (TUNEL), caspase-3, and bcl-2 labeling. The TUNEL, caspase-3, and bcl-2 staining scores were found to increase in group 3 rats following the ovariectomy compared to the sham-operated group. The ERT decreased these scores in rats with or without the ovariectomy; however, these differences were not statistically significant. These data suggest that estrogen does not significantly affect lens epithelial cell apoptosis. Further studies are needed to gain a better understanding of the protective mechanism of estrogen and to provide new ideas for the treatment and prevention of cataract.

Glutathione and catalase suppress TGFbeta-induced cataract-related changes in cultured rat lenses and lens epithelial explants

PURPOSE

The damaging effects of oxidative stress and transforming growth factor-beta (TGFbeta)-induced transdifferentiation of lens epithelial cells have both been implicated independently in the etiology of cataract. The aim of this study was to investigate whether the presence of antioxidant systems in the lens influences the ability of lens epithelial cells to respond to TGFbeta.

METHODS

Whole lenses from young rats were cultured with or without TGFbeta in the presence or absence of reduced glutathione (GSH). Lens epithelial explants from weanling rats were used to investigate the effects of GSH and catalase on TGFbeta-induced cataract-related changes. Lenses were monitored for opacification for three to four days, photographed, and then processed for routine histology. Explants were assessed by phase contrast microscopy, enzyme-linked immunosorbent assay (ELISA) of alpha-smooth muscle actin (alphaSMA), and/or immunolocalization of alphaSMA and Pax6, markers for transdifferentiation and normal lens epithelial phenotype, respectively.

RESULTS

In cultured lenses, GSH strongly suppressed TGFbeta-induced opacification and subcapsular plaque formation. In explants, both GSH and catalase suppressed changes typically associated with TGFbeta-induced transdifferentiation including wrinkling of the lens capsule, cell-surface blebbing, apoptotic cell loss, induction of alphaSMA, and loss of Pax6 expression.

CONCLUSIONS

This study suggests that antioxidant systems present in the normal lens, which protect the epithelium against the damaging effects of reactive oxygen species, may also serve to protect it against the potentially cataractogenic effects of TGFbeta. Taken together with other recent studies, it also raises the possibility that TGFbeta may induce cataract-related changes in lens epithelial cells via release of hydrogen peroxide.

Estrogen protects against radiation-induced cataractogenesis

Cataractogenesis is a complication of radiotherapy when the eye is included in the treatment field. Low doses of densely ionizing space radiation may also result in an increased risk of cataracts in astronauts. We previously reported that estrogen (17-beta-estradiol), when administered to ovariectomized rats commencing 1 week before gamma irradiation of the eye and continuously thereafter, results in a significant increase in the rate and incidence of cataract formation and a decreased latent period compared to an ovariectomized control group. We therefore concluded that estrogen accelerates progression of radiation-induced opacification. We now show that estrogen, if administered continuously, but commencing after irradiation, protects against radiation cataractogenesis. Both the rate of progression and incidence of cataracts were greatly reduced in ovariectomized rats that received estrogen treatment after irradiation compared to ovariectomized rats. As in our previous study, estradiol administered 1 week prior to irradiation at the time of ovariectomy and throughout the period of observation produced an enhanced rate of cataract progression. Estrogen administered for only 1 week prior to irradiation had no effect on the rate of progression but resulted in a slight reduction in the incidence. We conclude that estrogen may enhance or protect against radiation cataractogenesis, depending on when it is administered relative to the time of irradiation, and may differentially modulate the initiation and progression phases of cataractogenesis. These data have important implications for astronauts and radiotherapy patients.

Posterior capsule opacification

Posterior Capsule Opacification (PCO) is the most common complication of cataract surgery. At present the only means of treating cataract is by surgical intervention, and this initially restores high visual quality. Unfortunately, PCO develops in a significant proportion of patients to such an extent that a secondary loss of vision occurs. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior and the entire posterior capsule. The bag remains in situ, partitions the aqueous and vitreous humours, and in the majority of cases, houses an intraocular lens. The production of a capsular bag following surgery permits a free passage of light along the visual axis through the transparent intraocular lens and thin acellular posterior capsule. However, on the remaining anterior capsule, lens epithelial cells stubbornly reside despite enduring the rigours of surgical trauma. This resilient group of cells then begin to re-colonise the denuded regions of the anterior capsule, encroach onto the intraocular lens surface, occupy regions of the outer anterior capsule and most importantly of all begin to colonise the previously cell-free posterior capsule. Cells continue to divide, begin to cover the posterior capsule and can ultimately encroach on the visual axis resulting in changes to the matrix and cell organization that can give rise to light scatter. This review will describe the biological mechanisms driving PCO progression and discuss the influence of IOL design, surgical techniques and putative drug therapies in regulating the rate and severity of PCO.

Mitochondrial superoxide dismutase activation with 17 beta-estradiol-treated human lens epithelial cells

PURPOSE

17 beta-estradiol (17beta-E(2)) protects human lens epithelial cells against oxidative stress by preserving mitochondrial function in part via the non-genomic rapid activation of prosurvival signal transduction pathways. The study described herein examined whether 17beta-E(2) also elicits genomic protection by influencing the expression (and activity) of mitochondrial-associated manganese superoxide dismutase (MnSOD) as a possible parallel mechanism by which 17beta-E(2) protects against oxidative stress.

METHODS

Virally-transformed human lens epithelial cells (HLE-B3) were pre-incubated with 17beta-E(2), and mRNA or protein lysates were collected over a time course ranging from 90 min to 24 h. Positive expression of lens epithelial cell MnSOD mRNA was determined by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR), and its levels were monitored by real-time PCR up to 24 h after 17beta-E(2) administration. Western blot analysis was used to examine the pattern of protein expression as influenced by 17beta-E(2) treatment. MnSOD activity as influenced by 17beta-E(2) was determined by measuring enzymatic activity.

RESULTS

A significant rapid increase in the activity of MnSOD was observed with HLE-B3 cells by 90 min post-bolus addition of 17beta-E(2), which returned to control level by 240 min. Neither an increase in MnSOD mRNA nor in protein expression was detected up through 24 h.

CONCLUSIONS

These data demonstrate that 17beta-E(2) rapidly and transiently increases the activity of MnSOD but influences neither its mRNA expression nor its protein expression. The results suggest that (estrogen-activated) MnSOD plays an important role against mitochondrial oxidative stress by diminishing reactive oxygen species, thus promoting cell survival.

Ten-year incidence of age-related cataract and cataract surgery in an older Australian population. The Blue Mountains Eye Study

PURPOSE

To estimate the 10-year incidence of cataract and cataract surgery in an older Australian population.

DESIGN

Prospective population-based study.

PARTICIPANTS

Persons at least 49 years old living in 2 postcode areas west of Sydney, Australia.

METHODS

Eye examinations were performed at baseline and at 5- and 10-year follow-up visits. Lens photographs were taken and graded by masked graders using the Wisconsin Cataract Grading System.

MAIN OUTCOME MEASURES

Incidences of nuclear cataract, cortical cataract, posterior subcapsular cataract (PSC), and cataract surgery.

RESULTS

Ten-year person-specific incidences were 36.0% for nuclear cataract, 28.0% for cortical cataract, 9.1% for PSC, and 17.8% for cataract surgery. Corresponding rates were 31.7%, 24.4%, 8.2%, and 14.4%, respectively, in men and 39.3%, 30.8%, 9.8%, and 20.1%, respectively, in women. The incidence for each type of cataract and cataract surgery was positively associated with age (P<0.0001). Women had a significantly higher incidence than men for nuclear cataract (P = 0.04), cortical cataract (P = 0.007), any cataract (P = 0.0006), and cataract surgery (P = 0.03) after adjusting for age. There was no significant gender difference for PSC. The mean age at cataract surgery was 75.8 years, and there was no significant gender difference (P = 0.9). Among persons who developed any cataract, 22% had more than one type and 1.3% had all 3 types present. Nuclear cataract and PSC were significantly associated with visual impairment (visual acuity worse than 20/40).

CONCLUSION

Age- and gender-specific cataract incidences in this study were similar to those reported from the U.S. Beaver Dam Eye Study. In this study, 72% of the participants were affected by cataract or had had cataract surgery over the 10-year follow-up period.

Effect of protocatechualdehyde on receptor for advanced glycation end products and TGF-β1 expression in human lens epithelial cells cultured under diabetic conditions and on lens opacity in streptozotocin-diabetic rats

Advanced glycation end products and transforming growth factor-beta (TGF-beta) have been implicated in the development of diabetic complications such as cataract. The diverse metabolic effects of protocatechualdehyde (PCA, 3, 4-dihydroxybenzaldehyde) include the inhibition of aldose reductase and oxidation, two processes that are involved in the development of complications in diabetic patients. Here, the potential therapeutic effects of PCA in the treatment of diabetic complications were studied by determining this compound's ability to inhibit the formation of advanced glycation end products-bovine serum albumin (BSA) and the expression of receptor for advanced glycation end products and TGF-beta1 in human lens epithelial cells cultured under diabetic conditions. In addition, the ability of PCA to suppress lens opacification in streptozotocin-diabetic rats was analyzed. PCA significantly reduced advanced glycation end products-BSA formation in vitro and was more effective than aminoguanidine. In human lens epithelial cells, PCA significantly inhibited the induction of receptor for advanced glycation end products protein and mRNA expression by the receptor for advanced glycation end products-specific ligand S100b. Moreover, PCA inhibited high glucose- or S100b-induced TGF-beta1 protein and mRNA expression as well as nuclear accumulation of phosphorylated Smad2/3. In streptozotocin-induced diabetic cataract in rats, oral administration of PCA (25 mg/kg body weight) for 8 weeks significantly ameliorated the development of lens opacity (cataract) with effect on glycemic control. These results suggest that PCA is of therapeutic interest with respect to the prevention of diabetic complications such as diabetic cataract.

Effect of Hormone Replacement Therapy in Women on Ocular Refractive Status and Aberrations

PURPOSE

To evaluate the effects of hormone replacement therapy (HRT) on refractive status, corneal topography, and aberrations of the eye in postmenopausal women.

METHODS

Thirty-six healthy postmenopausal women (72 eyes) were included in the study. All patients received HRT that consisted of 0.625 mg/day conjugated estrogen and 5 mg/day medroxyprogesterone acetate in a continuous combined regimen. Schirmer II test and tear film break-up time (BUT) were performed on all patients at the time of enrollment and 6 months after initiation of HRT. Refractive status, corneal topography, and wavefront aberrations were evaluated with the NIDEK Optical Path Difference-Scan before and 6 months after HRT was initiated.

RESULTS

Mean patient age was 50.8 +/- 2.6 years (range: 47 to 57 years). The mean duration of menopause was 2.7 +/- 0.8 years (range: 1.4 to 3.5 years). The Schirmer II test and tear film BUT measurements were significantly lower after HRT (P < .05). Before HRT, the mean spherical equivalent refraction was -0.19 +/- 1.79 diopters (D) (range: -4.38 to +3.00 D). After HRT, the mean spherical equivalent refraction was -0.22 +/- 1.81 D (range: -4.63 to +/- 2.63 D). No significant differences were noted between refractive status, corneal topography, and wavefront aberrations of eyes of patients before and 6 months after HRT (P > .05).

CONCLUSIONS

Hormone replacement therapy in postmenopausal women does not significantly affect refractive status, corneal topography, and wavefront aberrations of the eye at 6-month follow-up.

Prevention of posterior capsular opacification through cyclooxygenase-2 inhibition

PURPOSE

To determine if cyclooxygenase-2 (COX-2) is upregulated when lens epithelial cells (LEC) in clinical samples of cataracts and posterior capsule opacification (PCO) undergo epithelial-mesenchymal transition (EMT)-like changes. We also wanted to learn if inhibition of the enzymatic activity of COX-2 could prevent PCO formation.

METHODS

To ensure that EMT-like changes were occurring in LEC, real-time RT-PCR was used to examine expression of EMT markers. Clinical samples of canine cataracts and PCO were examined for COX-2 expression using immunohistochemistry, western blot analysis, and real-time RT-PCR. The COX-2 inhibitors, rofecoxib and celecoxib, were used in an ex vivo model of PCO formation, and the effects on cellular migration, proliferation, and apoptosis were analyzed using immunohistochemistry and western blots. Prostaglandin E2 (PGE2) expression was examined with ELISA.

RESULTS

Markers of EMT, such as lumican, Snail, Slug, and COX-2 were expressed in LEC. In clinical samples of cataracts and PCO, there was overexpression of COX-2 protein and mRNA. Both rofecoxib and celecoxib were effective at inhibiting PCO formation in our ex vivo model. Prevention of PCO with the COX-2 inhibitors appeared to work through decreased migration and proliferation, and increased apoptosis. Neither of the drugs had a toxic effect on confluent LEC and appeared to inhibit PCO through their pharmacologic action. Synthesis of PGE2 was inhibiting in the capsules treated with the COX-2 inhibiting drugs.

CONCLUSIONS

Extracapsular phacoemulsification cataract surgery is the most common surgical procedure performed in human and veterinary ophthalmology. The most frequent postoperative complication is PCO. The LEC that remain adhered to the lens capsule undergo EMT-like changes, proliferate, and migrate across the posterior lens capsule causing opacities. We have shown that COX-2, a protein associated with EMT, is upregulated in canine cataracts and PCO. Inhibiting the enzymatic activity effectively prevented EMT of LEC in our ex vivo model of PCO through pharmacologic action, and not acute toxicity. These findings indicate that using COX-2 inhibitors in vivo may be an effective technique in preventing PCO.

Incidence and risk factors of Nd:YAG capsulotomy after phacoemulsification in non-diabetic and diabetic patients

PURPOSE

To estimate the cumulative incidence and identify the risk factors of posterior capsule opacification (PCO) that required Nd:YAG capsulotomy in non-diabetic and diabetic patients.

METHODS

Retrospective case-note review of 806 consecutive patients that underwent phacoemulsification and intraocular lens (IOL) implantation, 327 (40.6%) of whom were diabetic.

RESULTS

The cumulative incidence of Nd:YAG capsulotomy were 10.6%, 14.8%, 21.2% and 28.6% in non-diabetic patients; and 9%, 9.4%, 15.3% and 5.3% in diabetic patients after 1, 2, 3 and 4 years, respectively. A multivariate Cox regression analysis showed that, over the follow-up period, diabetes mellitus was associated with a decreased risk of Nd:YAG capsulotomy (hazard ratio [HR]=0.69; 95% confidence interval [CI] 0.47-0.99; P=0.047), whereas age of 65 years or younger (HR=1.58; 95% CI 1.09-2.27; P=0.02), polymethylmethacrylate (PMMA) (HR=3.98; 95% CI 1.60-9.95; P=0.003) or plate-haptic silicone IOLs (HR=3.75; 95% CI 1.60-8.80; P=0.002) in comparison with three-piece silicone IOLs, postoperative inflammation (HR=2.62; 95% CI 1.56-4.42; P<0.001) and pars plana vitrectomy (HR=1.85; 95% CI 1.20-2.83; P=0.005) were associated with an increased risk. Subgroup analysis showed that in non-diabetic patients, male gender (HR=1.63; 95% CI 1.04-2.57; P=0.03) was an additional risk factor and in diabetic patients there was no significant association between diabetes type, duration or retinopathy grade and the risk of Nd:YAG capsulotomy.

CONCLUSION

Although diabetes mellitus appears to be associated with a lower long-term incidence and a decreased risk of Nd:YAG capsulotomy, younger age, pars plana vitrectomy, postoperative inflammation, plate-haptic silicone and PMMA IOLs in addition to male gender in non-diabetic patients appear to be associated with a greater risk. Estimation of the incidence and risk factors of PCO should help in patient counselling and to design methods to reduce or prevent its development.