Estrogen receptor gene polymorphisms and their influence on clinical status of Caucasian patients with primary open angle glaucoma

Association of Gene Polymorphisms with Normal Tension Glaucoma: A Systematic Review and Meta-Analysis

BACKGROUND

Normal tension glaucoma (NTG) is becoming a more and more serious problem, especially in Asia. But the pathological mechanisms are still not illustrated clearly. We carried out this research to uncover the gene polymorphisms with NTG.

METHODS

We searched in Web of Science, Embase, Pubmed and Cochrane databases for qualified case-control studies investigating the association between single nucleotide polymorphisms (SNPs) and NTG risk. Odds ratios (ORs) and 95% confidence intervals (CIs) for each SNP were estimated by fixed- or random-effect models. Sensitivity analysis was also performed to strengthen the reliability of the results.

RESULTS

Fifty-six studies involving 33 candidate SNPs in 14 genetic loci were verified to be eligible for our meta-analysis. Significant associations were found between 16 SNPs (rs166850 of OPA1; rs10451941 of OPA1; rs735860 of ELOVL5; rs678350 of HK2; c.603T>A/Met98Lys of OPTN; c.412G>A/Thr34Thr of OPTN; rs10759930 of TLR4; rs1927914 of TLR4; rs1927911 of TLR4; c.*70C>G of EDNRA; rs1042522/-Arg72Pro of P53; rs10483727 of SIX1-SIX6; rs33912345 of SIX1-SIX6; rs2033008 of NCK2; rs3213787 of SRBD1 and c.231G>A of EDNRA) with increased or decreased risk of NTG.

CONCLUSIONS

In this study, we confirmed 16 genetic polymorphisms in 10 genes (OPA1, ELOVL5, HK2, OPTN, TLR4, EDNRA, P53, NCK2, SRBD1 and SIX1-SIX6) were associated with NTG.

Estrogen dysregulation, intraocular pressure, and glaucoma risk

Characterized by optic nerve atrophy due to retinal ganglion cell (RGC) death, glaucoma is the leading cause of irreversible blindness worldwide. Of the major risk factors for glaucoma (age, ocular hypertension, and genetics), only elevated intraocular pressure (IOP) is modifiable, which is largely regulated by aqueous humor outflow through the trabecular meshwork. Glucocorticoids such as dexamethasone have long been known to elevate IOP and lead to glaucoma. However, several recent studies have reported that steroid hormone estrogen levels inversely correlate with glaucoma risk, and that variants in estrogen signaling genes have been associated with glaucoma. As a result, estrogen dysregulation may contribute to glaucoma pathogenesis, and estrogen signaling may protect against glaucoma. The mechanism for estrogen-related protection against glaucoma is not completely understood but likely involves both regulation of IOP homeostasis and neuroprotection of RGCs. Based upon its known activities, estrogen signaling may promote IOP homeostasis by affecting extracellular matrix turnover, focal adhesion assembly, actin stress fiber formation, mechanosensation, and nitric oxide production. In addition, estrogen receptors in the RGCs may mediate neuroprotective functions. As a result, the estrogen signaling pathway may offer a therapeutic target for both IOP control and neuroprotection. This review examines the evidence for a relationship between estrogen and IOP and explores the possible mechanisms by which estrogen maintains IOP homeostasis.

Identification of Estrogen Signaling in a Prioritization Study of Intraocular Pressure-Associated Genes

Elevated intraocular pressure (IOP) is the only modifiable risk factor for primary open-angle glaucoma (POAG). Herein we sought to prioritize a set of previously identified IOP-associated genes using novel and previously published datasets. We identified several genes for future study, including several involved in cytoskeletal/extracellular matrix reorganization, cell adhesion, angiogenesis, and TGF-β signaling. Our differential correlation analysis of IOP-associated genes identified 295 pairs of 201 genes with differential correlation. Pathway analysis identified β-estradiol as the top upstream regulator of these genes with ESR1 mediating 25 interactions. Several genes (i.e., EFEMP1, FOXC1, and SPTBN1) regulated by β-estradiol/ESR1 were highly expressed in non-glaucomatous human trabecular meshwork (TM) or Schlemm’s canal (SC) cells and specifically expressed in TM/SC cell clusters defined by single-cell RNA-sequencing. We confirmed ESR1 gene and protein expression in human TM cells and TM/SC tissue with quantitative real-time PCR and immunofluorescence, respectively. 17β-estradiol was identified in bovine, porcine, and human aqueous humor (AH) using ELISA. In conclusion, we have identified estrogen receptor signaling as a key modulator of several IOP-associated genes. The expression of ESR1 and these IOP-associated genes in TM/SC tissue and the presence of 17β-estradiol in AH supports a role for estrogen signaling in IOP regulation.

The Association Between Genetic Polymorphisms in Estrogen Receptor Genes and the Risk of Ocular Disease: A Meta-Analysis

Objectives:

To evaluate the association between estrogen receptor (ER) genes polymorphisms and the risk of ocular disease.

Materials and Methods:

A meta-analysis was performed of all available studies that investigated the association between ER gene polymorphisms and the risk of ocular disease.

Results:

Studies that were selected based on inclusion criteria reported 5 and 4 single-nucleotide polymorphisms (SNPs) identified in the ESR1 (ERα) (rs2234093, rs12154178, rs1884054, rs1801132, and rs9340799) and ESR2 (ERβ) (rs1268656, rs7159462, rs1256031, and rs4986938) genes, respectively. The pooled result showed a significant association between ESR2 rs1256031 gene polymorphism and ocular disease (odds ratio: 0.55, 95% confidence interval: 0.41-0.74, p<0.0001).

Conclusion:

The recessive genotype of ESR2 rs1256031 gene polymorphism had a protective effect against ocular disease, which supports the hypothesis that the estrogen-signaling pathway through ERβ plays a pivotal role in the pathogenesis of ophthalmic disorders.

Girl Power in Glaucoma: The Role of Estrogen in Primary Open Angle Glaucoma

Estrogen is essential in maintaining various physiological features in women, and a decline in estrogen levels are known to give rise to numerous unfortunate symptoms associated with menopause. To alleviate these symptoms hormone replacement therapy with estrogen is often used, and has been shown to be fruitful in improving quality of life in women suffering from postmenopausal discomforts. An often forgotten condition associated with menopause is the optic nerve disorder, glaucoma. Thus, estrogen may also have an impact in maintaining the retinal ganglion cells (RGCs), which make up the optic nerve, thereby preventing glaucomatous neurodegeneration. This review aims to provide an overview of possible associations of estrogen and the glaucoma subtype, primary open-angle glaucoma (POAG), by evaluating the current literature through a PubMed-based literature search. Multiple in vitro and in vivo studies of RGC protection, as well as clinical and epidemiological data concerning the well-defined retinal neurodegenerative disorder POAG have been reviewed. Over all, deficiencies in retinal estrogen may potentially instigate RGC loss, visual disability, and eventual blindness. Estrogen replacement therapy may therefore be a beneficial future treatment. However, more studies are needed to confirm the relevance of estrogen in glaucoma prevention.

Clinical Features of Pseudoexfoliative Glaucoma in Treated Polish Patients

PURPOSE

The aim of this study was to describe clinical characteristics of glaucomatous optic neuropathy in treated Polish patients with pseudoexfoliative glaucoma.

METHODS

In the course of the study, 348 eyes of 231 patients with pseudoexfoliative glaucoma. The patients involved in the study were treated in the Department of Diagnostic and Microsurgery of Glaucoma in Lublin between 2012 and 2019. The following parameters were assessed in the examination: visual acuity, slit-lamp biomicroscopy with evaluation of anterior segment of the eye, gonioscopic examination, stereoscopic fundus examination of the eye, intraocular pressure, visual field, and pachymetry.

RESULTS

The mean age of all the patients was 73.16 years (SD±8.03). The mean age of women was 74.06 (SD±6.97), and the mean age of men was 71.8 (SD±8.51, p=0.006265). Women represented 37.93% (n=132) of the studied group, while men 62.07% (n=216). In the group of patients younger than 65 years of age, 27.9% were male and 15% female (p=0.0021). In the whole studied group, mean peak IOP was 29.25 mmHg with higher mean values in male patients (M vs F: 33.24 mmHg vs 26.86 mmHg; p=0.000). Peak values exceeding 30 mmHg were significantly more frequent in males (M vs F: 56.5% vs 31.9%; p=0.0000). Peak IOP never exceeding 21 mmHg was observed in 18.6% of the patients. The mean value of MD (Mean Deviation) was -12.85 dB in the whole group. The men were more likely to have more advanced glaucoma, according to MD (M vs F: -16.35 dB vs -11.13 dB; p=0.0000).

CONCLUSION

Pseudoexfoliative glaucoma was more frequently observed in men with younger age, higher IOP, and more advanced glaucoma. Normotensive glaucoma was observed in 18.6% of the patients with pseudoexfoliative glaucoma.

The association of estrogen-signaling pathways and susceptibility to open-angle glaucoma

Background

Glaucoma is a complex multivariate disorder characterized by retinal ganglion cell (RGC) loss and optic nerve degeneration. Evidence suggests the role of estradiol (E2) and the etiology of glaucoma. Therefore, this present study evaluates the association between estrogen-signaling pathways and the risk of open-angle glaucoma (OAG).

Results

Meta-analysis was performed from available studies that investigated intraocular pressure (IOP) in patients treated with or without hormone replacement therapy (HRT) and studies that evaluated the associations between estrogen receptor (ER) polymorphisms and the risk of OAG. The pooled result showed that HRT had a positive effect in lowering IOP. Moreover, ERβ polymorphisms showed a significant association with the risk of OAG.

Conclusion

This report supports the notion that estrogen-signaling pathways play a pivotal role in the development of OAG.