Aqueous humor levels of TGFβ2 and SFRP1 in different types of glaucoma

Genes as drugs for glaucoma: latest advances

PURPOSE OF REVIEW

To provide the latest advances on the future use of gene therapy for the treatment of glaucoma.

RECENT FINDINGS

In preclinical studies, a number of genes have been shown to be able to reduce elevated intraocular pressure (IOP), and to exert neuroprotection of the retinal ganglion cells. These genes target various mechanisms of action and include among others: MMP3 , PLAT, IκB, GLIS, SIRT, Tie-2, AQP1. Some of these as well as some previously identified genes ( MMP3, PLAT, BDNF, C3, TGFβ, MYOC, ANGPTL7 ) are starting to move onto drug development. At the same time, progress has been made in the methods to deliver and control gene therapeutics (advances in these areas are not covered in this review).

SUMMARY

While preclinical efforts continue in several laboratories, an increasing number of start-up and large pharmaceutical companies are working on developing gene therapeutics for glaucoma ( Sylentis, Quetera/Astellas, Exhaura, Ikarovec, Genentech, Regeneron, Isarna, Diorasis Therapeutics ). Despite the presence of generic medications to treat glaucoma, given the size of the potential world-wide market (∼$7B), it is likely that the number of companies developing glaucoma gene therapies will increase further in the near future.

Low expression of TGF-β2 and matrilin2 in human aqueous humour with acute primary angle closure

Primary angle-closure glaucoma (PACG) is the leading cause of irreversible blindness in the world. Angle closure induced by pupil block and secondary iris synechia is the fundamental pathology of the PACG. The molecular mechanisms of angle closure have not yet been clearly illustrated. This study was designed to investigate the protein difference in the aqueous humour and explore new biomarker of the PACG. Aqueous humour (AH) was collected from patients with acute primary angle closure (APAC) and cataract (n = 10 in APAC group) and patients with cataract only (n = 10 in control group). Samples were pooled and measured using label-free proteome technology. Then, the differentially expressed proteins (DEPs) were verified by ELISA using independent AH samples (n = 20 each group). More than 400 proteins were revealed in both groups through proteomics. Comparing the two groups, there were 91DEPs. These proteins participate in biological activities such as inflammation, fibrosis, nerve growth and degeneration and metabolism. We found that the expression of transforming growth factor-β2 and matrilin2 was downregulated in the APAC group. The two proteins are related to inflammation and extracellular matrix formation, which might be involved in angle closure. This study characterized DEPs in AH of the APAC and found a downregulated protein matrilin2.

An Overview of Current Glaucomatous Trabecular Meshwork Models

PURPOSE

To provide an overview of the existing alternative models for studying trabecular meshwork (TM).

METHODS

Literature review.

RESULTS

The TM is a complex tissue that regulates aqueous humor outflow from the eye. Dysfunction of the TM is a major contributor to the pathogenesis of open-angle glaucoma, a leading cause of irreversible blindness worldwide. The TM is a porous structure composed of trabecular meshwork cells (TMC) within a multi-layered extracellular matrix (ECM). Although dysregulation of the outflow throughout the TM represents the first step in the disease process, the underlying mechanisms of TM degeneration associate cell loss and accumulation of ECM, but remain incompletely understood, and drugs targeting the TM are limited. Therefore, experimental models of glaucomatous trabeculopathy are necessary for preclinical screening, to advance research on this disease's pathophysiology, and to develop new therapeutic strategies targeting the TM. Traditional animal models have been used extensively, albeit with inherent limitations, including ethical concerns and limited translatability to humans. Consequently, there has been an increasing focus on developing alternative in vitro models to study the TM. Recent advancements in three-dimensional cell culture and tissue engineering are still in their early stages and do not yet fully reflect the complexity of the outflow pathway. However, they have shown promise in reducing reliance on animal experimentation in certain aspects of glaucoma research.

CONCLUSION

This review provides an overview of the existing alternative models for studying TM and their potential for advancing research on the pathophysiology of open-angle glaucoma and developing new therapeutic strategies.

Factors Correlated With Mid-Term Morphology of Functional Blebs Following Implantation of Preserflo MicroShunt Using AS-OCT

Purpose

Evaluating bleb morphology is crucial after glaucoma filtering surgery. Advances in anterior segment optical coherence tomography (AS-OCT) allow for objective assessment. While various parameters differentiate functional from failed blebs, limited information exists regarding variations within functional blebs. This study aimed to identify factors influencing morphology of functional blebs following implantation of Preserflo MicroShunt.

Methods

Eyes with functional blebs after Preserflo were retrospectively included. Age, gender, lens status, preoperative intraocular pressure (pre-IOP) and number of glaucoma medications were documented along with biometric measurements as axial length (AL), white-to-white distance, and anterior chamber depth. Postoperative data included time elapsed since surgery (TaS) and postoperative IOP (post-IOP). Bleb dimensions were measured using AS-OCT including maximal bleb height (MBH), width, length (MBL), bleb wall thickness (BWT), and bleb distance to limbus (DtL) along with dimensions of episcleral lake (maximal height, width [MLW], and length). Linear regression models were applied to correlate these parameters with bleb dimensions.

Results

Included were 50 eyes from 50 patients. Mean IOP decreased from 25.3 ± 10.0 to 11.9 ± 3.0 mm Hg after 278.5 ± 221.9 days after surgery. MBH correlated negatively with age (unstandardized coefficients [uSC] = -0.012) and TaS (uSC = -0.001, P = 0.008 for both). BWT correlated negatively with age (uSC = -0.013, P = 0.02), MBL with AL (uSC = -0.566, P = 0.01) and MLW with pre-IOP (uSC = -0.073, P = 0.02). DtL exhibited a positive correlation with post-IOP (uCS = 0.136, P = 0.02).

Conclusions

Morphology of functional blebs might be influenced by multiple factors such as age, TaS, AL, and pre- and post-IOP.

Translational Relevance

Age, time after surgery, axial length, and preoperative and postoperative IOP could affect the morphology of a functional bleb; hence, these factors should be taken into consideration when making treatment decisions.

Aqueous Humor TGF-β2 and Its Association With Intraocular Pressure in a Naturally Occurring Large Animal Model of Glaucoma

Purpose

Transforming growth factor (TGF)-β2 has been widely implicated in human glaucoma pathology. The purpose of this study was to determine the source of TGF-β2 in aqueous humor (AH) and its relationship with intraocular pressure (IOP) in an inherited large animal model of glaucoma.

Methods

Sixty-six glaucomatous cats homozygous for LTBP2 mutation, and 42 normal cats were studied. IOP was measured weekly by rebound tonometry. AH was collected by anterior chamber paracentesis from each eye under general anesthesia, and serum samples collected from venous blood concurrently. Concentrations of total, active and latent TGF-β2 in AH and serum samples were measured by quantitative sandwich immunoassay. For comparisons between groups, unpaired t-test or Mann Whitney test were used, with P < 0.05 considered significant. The relationships between TGF-β2 concentrations and IOP values were examined by Pearson's correlation coefficient and generalized estimating equation.

Results

IOP and AH TGF-β2 concentrations were significantly higher in glaucomatous than in normal cats. AH TGF-β2 showed a significant, robust positive correlation with IOP in glaucomatous cats (r = 0.83, R2 = 0.70, P < 0.0001). Serum TGF-β2 did not correlate with AH TGF-β2 and was not significantly different between groups. TGF-β2 mRNA and protein expression were significantly increased in local ocular tissues in glaucomatous cats.

Conclusions

Enhanced, local ocular production of TGF-β2 with a robust positive association with IOP was identified in this spontaneous feline glaucoma model, providing a foundation for preclinical testing of novel therapeutics to limit disease-associated AH TGF-β2 elevation and signaling in glaucoma.

A ROCK inhibitor suppresses the transforming growth factor-beta-2-induced endothelial-mesenchymal transition in Schlemm's canal endothelial cells

In the normal eye, most of the aqueous humor drains through the trabecular meshwork (TM) and Schlemm's canal (SC). The concentration of transforming growth factor beta 2 (TGF-β2) is increased in the aqueous humor of primary open angle glaucoma patients. TGF-β2 increases outflow resistance by affecting the TM and SC, and endothelial-mesenchymal transition (EndMT) of SC cells is involved in these changes. Here, we investigated the effect of a ROCK inhibitor on TGF-β2-induced EndMT in SC cells. The ROCK inhibitor Y-27632 suppressed the TGF-β2-induced increase in the trans-endothelial electrical resistance (TER) and proliferation of SC cells. Y-27632 suppressed the expression of α-SMA, N-cadherin, and Snail, which are upregulated by TGF-β2. Moreover, TGF-β2 decreased mRNA levels of bone morphogenetic protein (BMP) 4 and increased those of the BMP antagonist gremlin (GREM1), but Y-27632 significantly suppressed these changes. Y-27632 also inhibited TGF-β2-induced phosphorylation of p-38 mitogen-activated protein kinase (MAPK). BMP4 and the p-38 MAPK inhibitor SB203580 suppressed the TGF-β2-induced TER elevation in SC cells. Moreover, SB203580 suppressed TGF-β2-induced upregulation of fibronectin, Snail, and GREM1. These results indicate that a ROCK inhibitor inhibited the TGF-β2-induced EndMT in SC cells, implying the involvement of p38 MAPK and BMP4 signaling.

Aqueous humor cytokine levels are associated with the severity of visual field defects in patients with primary open-angle glaucoma

BACKGROUND

To evaluate the aqueous humor (AH) levels of cytokines in primary open-angle glaucoma (POAG) patients and cataract patients.

METHODS

Thirty-eight POAG patients and 26 cataract patients were recruited. Peripheral blood (PB) was collected from each subject. The POAG group was divided into 2 subgroups according to the severity of visual field defects. The cutoff point of the mean deviation (MD) of the visual field was -12 dB. AH was obtained at the time of anterior chamber puncture during cataract or glaucoma surgery by using a 27-gauge needle attached to a microsyringe. AH and PB levels of interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-α), transforming growth factor-beta2 (TGF-β2) and IL-4 were assayed by enzyme-linked immunosorbent assay. Postoperative intraocular pressures (IOPs) of POAG patients were recorded during the follow-up period.

RESULTS

TNF-α and TGF-β2 showed significantly higher AH levels in the POAG group than in the cataract group (P < 0.001 and P = 0.001, respectively). For the POAG group, preoperative IOPs were significantly positively correlated with AH levels of TNF-α (r² = 0.129, P = 0.027) and TGF-β2 (r² = 0.273, P = 0.001). AH levels of TGF-β2 were significantly different among cataract patients, POAG patients with MD> -12 dB and POAG patients with MD≤ -12 dB (P = 0.001). AH levels of TNF-α were significantly positively associated with IOP reduction after trabeculectomy (P = 0.025). AH and PB levels of cytokines were not related to the long-term success of trabeculectomy.

CONCLUSION

The levels of TNF-α and TGF-β2 showed different profiles in POAG patients and cataract patients. AH levels of TGF-β2 were correlated with the severity of glaucomatous neuropathy in POAG patients. The findings suggest possible roles for cytokines in the pathogenesis and development of POAG.

Precision Medicine in Glaucoma: Artificial Intelligence, Biomarkers, Genetics and Redox State

Glaucoma is a multifactorial neurodegenerative illness requiring early diagnosis and strict monitoring of the disease progression. Current exams for diagnosis and prognosis are based on clinical examination, intraocular pressure (IOP) measurements, visual field tests, and optical coherence tomography (OCT). In this scenario, there is a critical unmet demand for glaucoma-related biomarkers to enhance clinical testing for early diagnosis and tracking of the disease's development. The introduction of validated biomarkers would allow for prompt intervention in the clinic to help with prognosis prediction and treatment response monitoring. This review aims to report the latest acquisitions on biomarkers in glaucoma, from imaging analysis to genetics and metabolic markers.

MicroRNA-210-3p mediates trabecular meshwork extracellular matrix accumulation and ocular hypertension - Implication for novel glaucoma therapy

Elevation of intraocular pressure (IOP) is a major, controllable risk factor of primary open-angle glaucoma (POAG). Transforming growth factor-β2 (TGF-β2)-induced excessive accumulation of extracellular matrix (ECM) in the trabecular meshwork (TM) has been demonstrated to contribute significantly to the development of high IOP. We previously showed that treatment with salidroside (Sal), a plant-derived glucoside, can ameliorate the TGF-β2-induced ECM expression in cultured human TM cells and reduce TGF-β2-induced ocular hypertension in mice. In the current study, its underlying molecular mechanism associated with microRNA-210-3p (miR-210-3p) was characterized. We discovered that, in TM tissues of POAG patients, there was an increase in miR-210-3p. And miR-210-3p mediated a portion of the pathological effects of TGF-β2 in vitro (excessive accumulation of ECM in cultured human TM cells) and in vivo (mouse ocular hypertension and ECM accumulation in the TM). Most interestingly, miR-210-3p was down-regulated by Sal, which appeared to mediate a significant portion of its IOP-lowering effect. Thus, these results shed light on the probable molecular mechanisms of TGF-β2 and Sal and indicate that manipulation of miR-210-3p level/activity represents a potential new therapeutic strategy for POAG.

Aquaporins in Cardiovascular System

Recent studies have shown that aquaporins (AQPs) are involved in the regulation of cardiovascular function and the development of related diseases, especially in cerebral ischemia, congestive heart failure, hypertension, and angiogenesis. Therefore, further studies are needed to elucidate the mechanism accounting for the association between AQPs and vascular function-related diseases, which may lead to novel approaches to the prevention and treatment of those diseases. Here we will discuss the expression and physiological roles of AQPs in vascular tissues and summarize recent progress in the research on AQPs related cardiovascular diseases.

The Association Between Age and Systemic Variables and the Longitudinal Trend of Intraocular Pressure in a Large-Scale Health Examination Cohort

Purpose

The detailed effects of age and systemic factors on intraocular pressure (IOP) have not been fully understood because of the lack of a large-scale longitudinal investigation. This study aimed to investigate the effect of various systemic factors on the longitudinal change of IOP.

Methods

There were a total of 20,909 eyes of 10,471 subjects from a health checkup cohort that were followed up for systemic factors: (i) age at baseline, (ii) sex, (iii) time series body mass index (BMI), (iv) time series smoking habits, (v) time series systolic and diastolic blood pressures (SBP and DBP), and (vi) time series 19 blood examinations (all of the time series data was acquired at each annual visit), along with IOP annually for at least 8 years. Then the longitudinal effect of the systemic factors on the change of IOP was investigated.

Results

IOP significantly decreased by −0.084 mm Hg/year. BMI, SBP, DBP, smoking habits, total triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and glycosylated hemoglobin A1c were not significantly associated with the change of IOP. Higher values of age, aspartate aminotransferase, hemoglobin, platelet, and calcium were suggested to be significantly associated with the decrease of IOP, whereas higher alanine aminotransferase, guanosine triphosphate, white blood cell count, red blood cell count, and female gender were significantly associated with the increase of IOP.

Conclusions

Age, aspartate aminotransferase, hemoglobin, platelet, calcium, alanine aminotransferase, guanosine triphosphate, white blood cell count, red blood cell count, and gender were the systemic variables significantly associated with the change of IOP.

TGF-β-Mediated Modulation of Cell-Cell Interactions in Postconfluent Maturing Corneal Endothelial Cells

Purpose

Transforming growth factor-beta (TGF-β) is known to influence many cell functions. In the corneal endothelium, TGF-β1 exerts contextual effects, promoting endothelial–mesenchymal transition in proliferating cells and enhancing barrier integrity in early confluent maturing cells. Herein, we studied how TGF-β isoforms participate in the formation of corneal endothelial intercellular junctions.

Methods

Corneal endothelial cells (CECs) were cultured using a two-phase media approach. When CECs reached confluence, the proliferation medium was replaced with maturation medium, which was supplemented or not with TGF-β isoforms. The cell morphology (circularity index), intercellular junction protein expression, trans-endothelial electrical resistance (TEER), and permeability of 7-day postconfluent CECs were assessed. Gene transcription and signaling pathways that were activated following maturation in the presence of TGF-β2 were also studied. The beneficial effect of TGF-β2 on CEC maturation was evaluated using ex vivo corneas mounted on a corneal bioreactor.

Results

The results showed increases in circularity index, membrane localization of junction-related proteins, and TEER when TGF-β isoforms were individually added during the maturation phase, and TGF-β2 was the most effective isoform. Gene profiling revealed an increase in extracellular matrix-related gene expression. In ex vivo cell adhesion experiments, CECs that were matured in the presence of TGF-β2 had a higher circularity index and cell density and exhibited cell membrane-localized junction-related protein expression at earlier time points.

Conclusions

These results suggest that TGF-β2 can strengthen cell–cell and cell–substrate adhesion, which accelerates barrier integrity establishment and thus enhances CEC functionality.

Effect of peripheral iridectomy on VEGF-A and TGF-β levels in rabbit aqueous humour

Background

Peripheral iridectomy (PI), routinely performed during glaucoma filtration surgery, may contribute to scarring. This study aims to determine whether PI alters the concentrations of VEGF-A and TGF-β isoforms in the rabbit aqueous humour.

Methods

Anterior chamber paracentesis (ACP) was performed in both eyes of six New Zealand white rabbits, with additional surgical PI performed in the right eyes. Eyes were examined on postoperative days (PODs) 1, 7, 30 and 60 by means of the tonopen, slit-lamp biomicroscopy, and bead-based cytokine assays for TGF-β and VEGF-A concentrations in the aqueous humor.

Results

ACP caused a significant reduction in intraocular pressure (IOP) from mean preoperative 11.47 ± 1.01 mmHg to 5.67 ± 1.63 mmHg on POD 1 while PI did not cause further IOP reduction. Limbal conjunctival vasculature appeared slightly increased on POD 1 in both ACP and PI eyes with PI also causing mild bleeding from damaged iris vessels. Two PI eyes developed fibrinous anterior chamber reaction and/ or peripheral anterior synechiae. Aqueous VEGF-A levels were not significantly different between eyes treated with ACP and PI. Aqueous TGF-β concentrations distributed in the ratio of 4:800:1 for TGF-β1:TGF-β2:TGF-β3 respectively. While aqueous TGF-β2 was not significantly induced by either procedure at any time point, TGF-β1 and TGF-β3 were significantly induced above baseline levels by PI on POD 1.

Conclusion

PI increases the risk of inflammation. The combined induction of aqueous TGF-β1 and TGF-β3 by PI in glaucoma surgery may impact surgery success in glaucoma subtypes sensitive to these isoforms.

Protein Biomarkers in Glaucoma: A Review

Glaucoma is a multifactorial disease. Early diagnosis of this disease can support treatment and reduce the effects of pathophysiological processes. A significant problem in the diagnosis of glaucoma is limited access to the tested material. Therefore, intensive research is underway to develop biomarkers for fast, noninvasive, and reliable testing. Biomarkers indicated in the formation of glaucoma include chemical compounds from different chemical groups, such as proteins, sugars, and lipids. This review summarizes our knowledge about protein and/or their protein-like derived biomarkers used for glaucoma diagnosis since 2000. The described possibilities resulting from a biomarker search may contribute to identifying a group of compounds strongly correlated with glaucoma development. Such a find would be of great importance in the diagnosis and treatment of this disorder, as current screening techniques have low sensitivity and are unable to diagnose early primary open-angle glaucoma.

Suberoylanilide hydroxamic acid (SAHA) inhibits transforming growth factor-beta 2-induced increases in aqueous humor outflow resistance

Transforming growth factor-beta 2 (TGF-β2) is highly concentrated in the aqueous humor of primary open-angle glaucoma patients. TGF-β2 causes fibrosis of outflow tissues, such as the trabecular meshwork (TM), and increases intraocular pressure by increasing resistance to aqueous humor outflow. Recently, histone deacetylase (HDAC) activity was investigated in fibrosis in various tissues, revealing that HDAC inhibitors suppress tissue fibrosis. However, the effect of HDAC inhibitors on fibrosis in the eye was not determined. Here, we investigated the effect of suberoylanilide hydroxamic acid (SAHA), an HDAC inhibitor, on TGF-β2-induced increased resistance to aqueous humor outflow. We found that SAHA suppressed TGF-β2-induced outflow resistance in perfused porcine eyes. Moreover, SAHA cotreatment suppressed TGF-β2-induced ocular hypertension in rabbits. The permeability of monkey TM (MTM) and Schlemm’s canal (MSC) cell monolayers was decreased by TGF-β2 treatment. SAHA inhibited the effects of TGF-β2 on the permeability of these cells. TGF-β2 also increased the expression of extracellular matrix proteins (fibronectin and collagen type I or IV) in MTM, MSC, and human TM (HTM) cells, while SAHA inhibited TGF-β2-induced extracellular matrix protein expression in these cells. SAHA also inhibited TGF-β2-induced phosphorylation of Akt and ERK, but did not inhibit Smad2/3 phosphorylation, the canonical pathway of TGF-β signaling. Moreover, SAHA induced the expression of phosphatase and tensin homolog, a PI3K/Akt signaling factor, as well as bone morphogenetic protein 7, an endogenous antagonist of TGF-β. These results imply that SAHA prevents TGF-β2-induced increases in outflow resistance and regulates the non-Smad pathway of TGF-β signaling in TM and MSC cells.

Candidate Glaucoma Biomarkers: From Proteins to Metabolites, and the Pitfalls to Clinical Applications

Glaucoma is an insidious group of eye diseases causing degeneration of the optic nerve, progressive loss of vision, and irreversible blindness. The number of people affected by glaucoma is estimated at 80 million in 2021, with 3.5% prevalence in people aged 40-80. The main biomarker and risk factor for the onset and progression of glaucoma is the elevation of intraocular pressure. However, when glaucoma is diagnosed, the level of retinal ganglion cell death usually amounts to 30-40%; hence, the urgent need for its early diagnosis. Molecular biomarkers of glaucoma, from proteins to metabolites, may be helpful as indicators of pathogenic processes observed during the disease's onset. The discovery of human glaucoma biomarkers is hampered by major limitations, including whether medications are influencing the expression of molecules in bodily fluids, or whether tests to validate glaucoma biomarker candidates should include human subjects with different types and stages of the disease, as well as patients with other ocular and neurodegenerative diseases. Moreover, the proper selection of the biofluid or tissue, as well as the analytical platform, should be mandatory. In this review, we have summarized current knowledge concerning proteomics- and metabolomics-based glaucoma biomarkers, with specificity to human eye tissue and fluid, as well the analytical approach and the main results obtained. The complex data published to date, which include at least 458 different molecules altered in human glaucoma, merit a new, integrative approach allowing for future diagnostic tests based on the absolute quantification of local and/or systemic biomarkers of glaucoma.

Crosstalk between transforming growth factor β-2 and Autotaxin in trabecular meshwork and different subtypes of glaucoma

BACKGROUND

Elevated transforming growth factor (TGF)-β2 in aqueous humor (AH) has been suggested to contribute to trabecular meshwork (TM) fibrosis and intraocular pressure (IOP) regulation in primary open-angle glaucoma (POAG), but TGF-β2 is downregulated in secondary open-angle glaucoma (SOAG). Because autotaxin (ATX) is upregulated in SOAG, we investigated the relationships and trans-signaling interactions of these mediators.

METHODS

The level of ATX in AH was determined using a two-site immunoenzymetric assay, and TGF-β levels were measured using the Bio-Plex Pro TGF-β Assay. RNA scope was used to assess the expression of ATX and TGF-β2 in human's eye specimen. And in vitro studies were performed using hTM cells to explore if trans-signaling of TGF-β2 regulates ATX expressions.

RESULTS

TGF-β2/ATX ratio was significantly high in AH of control or POAG compared with SOAG, and negatively correlated with IOP. RNA scope revelated positive expressions of both TGF-β2 and ATX in ciliary body (CB) and TM in control, but ATX expressions was significantly enhanced in SOAG. In hTM cells, ATX expressions were regulated by TGF-β2 with concentration-dependent manner. In counter, ATX also induced TGF-β1, TGF-β2 and TGFBI upregulations and activation of the Smad-sensitive promoter, as well as upregulation of fibrotic markers, and these upregulation was significantly suppressed by both TGF-β and ATX inhibition.

CONCLUSIONS

Trans-signaling of TGF-β2 regulates ATX expressions and thereby induced upregulations of TGF-βs or fibrosis of hTM. TGF-β2 trans-signaling potently regulate ATX transcription and signaling in hTM cells, which may reflect different profile of these mediators in glaucoma subtypes. Trial Registration This prospective observational study was approved by the Institutional Review Board of the University of Tokyo and was registered with the University Hospital Medical Information Network Clinical Trials Registry of Japan (ID: UMIN000027137). All study procedures conformed to the Declaration of Helsinki. Written informed consent was obtained from each patient.

Association of TGFB -509C>T promoter polymorphism with primary angle closure glaucoma in a North Indian Punjabi cohort

PURPOSE

Transforming growth factor beta (TGFB) is an important candidate gene implicated in glaucoma pathogenesis because it affects retinal ganglionic cell survival. The present study assessed the genetic association of -509C > T variant in the TGFB promoter region with primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) in a North Indian Punjabi population.

METHOD

A total of 867 subjects (307 POAG, 133 PACG cases and 427 controls) were recruited from the targeted population. Genotyping was done by PCR-RFLP method and the data was analyzed using PLINK software (v1.07). Logistic regression under different genetic models was applied and genotype phenotype correlation was assessed by one-way ANOVA.

RESULT

A statistically significant difference in the frequency of heterozygotes among PACG cases (53.16%) and controls (30.07%) (p = 0.0002) was observed. Genetic model analysis revealed that mutant "TT" genotype conferred 2-fold risk towards PACG development under recessive model (p = 0.0019) while dominant model and co-dominant model provided 0.62 and 0.37 fold protection against PACG (p = 0.025 and p = 0.0001, respectively). Data segregation based on sex revealed a strong protective effect of heterozygous 'CT' genotype against progression of PACG among females (p = 0.002, OR = 0.37, 95% CI = 0.19-0.70), but conferred 2.14-fold risk among female POAG subjects (p = 0.013).

CONCLUSION

The study revealed a strong genetic association of -509C > T variant in TGFB with PACG in females. There is a need to replicate the results in a larger PACG cohort in other populations and further assess the contribution of sex specific factors in modifying genetic susceptibility to PACG.

Association Between PM2.5 Exposure Level and Primary Open-Angle Glaucoma in Taiwanese Adults: A Nested Case-Control Study

Primary open-angle glaucoma (POAG) is the most common type of glaucoma. However, little is known about POAG in adults and exposure to air pollution. The current study aims to investigate whether exposure to particulate matter with a mass median aerodynamic diameter of ≤2.5 μm (PM_2.5) is associated with POAG diagnosis. Patient data were obtained from the Longitudinal Health Insurance Database 2010 (LHID2010) of Taiwan for the 2008–2013 period. PM_2.5 concentration data, collected from the Ambient Air Quality Monitoring Network established by the Environmental Protection Administration of Taiwan, were categorized into four groups according to World Health Organization (WHO) exposure standards for PM_2.5. We estimated the odds ratios (ORs) and 95% CIs for risk factors for POAG with logistic regression. The OR of per WHO standard level increase was 1.193 (95% CI 1.050–1.356). Compared with the normal level, the OR of WHO 2.0 level was 1.668 (95% CI 1.045–2.663, P < 0.05). After excluding confounding risk factors for POAG in this study, we determined that increased PM_2.5 exposure is related to POAG risk (ORs > 1, P < 0.05). In this study, PM_2.5 was an independent factor associated with open-angle glaucoma. Further research is required to better understand the mechanisms connecting PM_2.5 and open-angle glaucoma.

Effects of topical TGF-β1, TGF-β2, ATX, and LPA on IOP elevation and regulation of the conventional aqueous humor outflow pathway

PURPOSE

The effects of aqueous mediators possibly increasing the outflow resistance, transforming growth factor-β1 (TGF-β1), TGF-β2, autotaxin (ATX), and lysophosphatidic acid (LPA) on human trabecular meshwork (hTM) cells and monkey Schlemm's canal endothelial (SCE) cells were characterized and compared, and the effects of intracameral application of these mediators on intraocular (IOP) elevation were also examined.

METHODS

Cells were treated with TGF-β1, TGF-β2, ATX, LPA, or vehicle, and mRNA and protein expression levels of α-SMA, COL1A1, fibronectin, β-catenin, and ZO-1 were examined with real-time quantitative PCR (RT-qPCR) or immunofluorescence analyses or both. The permeability of cell monolayers was measured by determining the transendothelial electrical resistance (TEER) or with the fluorescein isothiocyanate (FITC)-dextran permeability assay. IOP was evaluated in rabbit eyes after intracameral administration of the mediators.

RESULTS

All mediators induced upregulation of α-SMA, COL1A1, and fibronectin in hTM cells. The effect of TGF-β2 on mRNA expression of fibrotic markers was statistically significantly greater than that of TGF-β1. The effects of ATX and LPA indicated the time-dependent difference in the upregulation of α-SMA, COL1A1, and fibronectin. The TEER and FITC-dextran permeability of the SCE cells was evaluated after treatment with TGF-β1 and TGF-β2, but no statistically significant change was observed within 24 h. ATX and LPA also reduced permeability statistically significantly after 3 h and 0.5 h, respectively, and the effect of LPA was more rapid compared to that of ATX. Statistically significant IOP elevation was observed in rabbit eyes as early as 0.5-2.0 h after ATX and LPA treatment and at 24 h after treatment with TGF-β2.

CONCLUSIONS

TGF-β2 and ATX and LPA regulate aqueous outflow by modulation of hTM cells and SCE cells, and differences in timing between the effects of each mediator were observed. ATX and LPA showed more rapid effects on IOP elevation than TGF-β2. It was suggested that TGF-β2 and ATX/LPA are involved in increases of IOP, but the timing and sustainability differ between mediators, and they may play specific roles in different glaucoma subtypes.

Proteome alterations in aqueous humour of primary open angle glaucoma patients

AIM

To unravel the primary open angle glaucoma (POAG) related proteomic changes in aqueous humour (AH).

METHODS

Totally 35 patients listed for cataract surgery (controls: n=12, age: 67.4±13.6y) or trabeculectomy for POAG (n=23, age: 72.5±8.3y) were included. AH samples of those patients were obtained during cataract surgery or trabeculectomy. AH samples were subsequently pooled into the experimental groups under equal contribution in terms of protein amount of each individual patient. Protein samples were analyzed by a linear trap quadrupol Orbitrap Mass Spectrometry device with an upstream liquid chromatography system. The obtained raw data were analyzed using the Maxquant proteome software and compared. Proteins with a fold-change ratio higher than a cut-off of 2 were considered as noticeably altered.

RESULTS

A total number of 175 proteins could be identified out of the AH from POAG and cataract by means of quantitative mass spectrometric analysis. Apolipoprotein D (fold change, 3.16 times), complement C3 (2.96), pigment epithelium-derived factor (2.86), dickkopf-related protein 3 (2.18) and wingless-related integration (Wnt) inhibitory factor 1 (2.35) were significantly upregulated within the AH of glaucoma compared to cataract serving as controls.

CONCLUSION

AH provides a tool to analyze changes in glaucoma and shows striking changes in Wnt signaling inhibitory molecules and other proteins.