Copper, Lysyl Oxidase Activity, and Collagen in Aqueous Humour of Primary Glaucoma: An Association with Clinical Parameters.

INTRODUCTION: To measure copper (Cu), lysyl oxidase (LOX) activity, and collagen levels in aqueous humour (AH) of primary glaucoma patients and correlate with clinical parameters. METHODS: 120 patients with 40 each of primary open angle glaucoma (POAG), primary angle closure glaucoma (PACG), and cataract controls were recruited in this case-control study. AH samples were collected during the trabeculectomy and cataract surgeries. Cu levels were measured using an atomic absorption spectrophotometer. LOX unit activity was determined by Amplex Red assay and collagen concentration by Sirius red assay. RESULTS: Significantly higher levels of Cu expressed as median (IQR) µmol/L were observed in POAG (p = 0.008) and PACG (p = 0.005) compared to controls. The LOX activity was increased in POAG and PACG (p = 0.04) compared to controls represented as median (IQR) µmol/min. The collagen levels given as median (IQR) mg/ml showed an insignificant increase in POAG and PACG compared to controls (p = 0.78). The LOX unit activity was correlated with visual field index (VFI), which showed a significant increase with the progression of the diseases (p < 0.05), whereas Cu levels were negatively correlated with LOX activity in AH. Cu and LOX activity showed weak correlation with YAG peripheral iridotomy (YAGPI), duration of anti-glaucoma medications, and highest preoperative intraocular pressure. CONCLUSION: Elevated Cu and LOX activity was observed in both POAG and PACG groups compared to controls. LOX activity showed notable increase with VFI as the severity of the disease. Although Cu levels are increased in glaucoma, it's insufficient to significantly increase the activity of LOX.

Anti-glaucoma medications lowered decorin and altered profibrotic proteins in human tenon's fibroblasts.

Long term exposure to anti-glaucoma medications (AGMs) leads to an increase in extracellular matrix (ECM) accumulation in primary glaucoma patients. This study aims to evaluate the effect of topical AGMs in primary human tenon's fibroblasts (HTFs) and analyze the expression of profibrotic and anti-fibrotic proteins. Primary HTFs were cultured from patients undergoing cataract (control) and trabeculectomy. The different types of AGMs in single/multiple combinations (BB, PG, AA, CAI, CH, combinations of 3- PG + AA + CAI, 4A- BB + PG + AA + CAI, 4B- BB + PG + CAI + CH and 5- BB + PG + AA + CAI + CH) on chronic exposure were tested for cell viability using MTT assay and morphological alterations. Profibrotic proteins mainly SPARC, LOXL2, COL1A1 and anti-fibrotic DCN were analyzed in treated HTFs using q-PCR and ELISA. Sirius red staining and collagen gel contraction (CGC) assay were performed to assess collagen synthesis and the contractility of HTFs, respectively. Except for AA and CH, the other AGMs at a higher concentration were found to decrease the cell viability of HTFs. The morphology of HTFs were altered on exposure to BB, CH and AA; Profibrotic proteins i.e., SPARC, LOXL2 and COL1A1 were significantly increased (p < 0.05) on exposure to a combination of AGMs with TGF-ß1, whereas the anti-fibrotic DCN expression was significantly lowered (p < 0.05) in single/multiple AGM exposure. Sirius red staining showed increased collagen synthesis with combinations of AGMs with TGF-ß1. Meanwhile, HTFs showed increased collagen gel contraction with TGF-ß1, CAI and CH. This study reveals that altered profibrotic proteins, with significantly lowered DCN on chronic exposure of AGMs in HTFs.

Copper mediates mitochondrial biogenesis in retinal pigment epithelial cells.

Age related macular degeneration (AMD) is a multifactorial disease with genetic, biochemical and environmental risk factors. We observed a significant increase in copper levels in choroid-RPE from donor eyeballs with AMD. Adult retinal pigment epithelial cells (ARPE19 cells) exposed to copper in-vitro showed a 2-fold increase in copper influx transporter CTR1 and copper uptake at 50 µM concentration. Further there was 2-fold increase in cytochrome C oxidase activity and a 2-fold increase in the mRNA expression of NRF 2 with copper treatment. There was a significant increase in mitochondrial biogenesis markers PGC1ß and TFAM which was confirmed by mitochondrial mass and copy number. On the contrary, in AMD choroid-RPE, the CTR1 mRNA was found to be significantly down-regulated compared to its respective controls. SCO1 and PGC1ß mRNA showed an increase in choroid-RPE. Our study proposes copper to play an important role in mitochondrial biogenesis in RPE cells.

Lowered Decorin With Aberrant Extracellular Matrix Remodeling in Aqueous Humor and Tenon's Tissue From Primary Glaucoma Patients.

Purpose: To evaluate the inflammatory cytokine, growth factors, extracellular matrix (ECM) remodeling genes, profibrotic and antifibrotic molecules in patients undergoing glaucoma filtration surgery (GFS). Additionally, the effect of preoperative antiglaucoma medications (AGMs) and postoperative bleb status were related to these parameters. Methods: Tenon's tissue and aqueous humour (AH) were collected from 207 patients undergoing GFS with primary open-angle glaucoma (POAG) (n = 77), primary angle-closure glaucoma (PACG) (n = 62), and cataract controls (n = 68). Monocyte chemoattractant protein-1 (MCP-1), connective tissue growth factor (CTGF), transforming growth factor ß1/2 (TGF-ß1/2), lysyl oxidase (LOX), lysyl oxidase L2 (LOXL2), elastin (ELN), collagen type 1 α 1 (COL1A1), secreted protein acidic and rich in cysteine (SPARC), α-smooth muscle actin (α-SMA), and decorin (DCN) were determined in tenon's tissue by real-time PCR and in AH using ELISA. Results: A significant increase was observed in the transcripts of MCP-1, TGF-ß2, and SPARC in POAG and PACG (P < 0.05); CTGF, TGF-ß1, LOX, LOXL2, ELN, COL1A1, and α-SMA in PACG (P < 0.05) compared with control. DCN transcript was significantly decreased in POAG and PACG (P < 0.05) compared with control. The protein levels of CTGF, TGF-ß1/ß2, ELN, SPARC, and LOXL2 was significantly elevated in POAG and PACG (P < 0.05); DCN was decreased (P < 0.05) compared with control. These parameters showed significant association with duration of preoperative AGMs and postoperative bleb status. Conclusions: This study demonstrates increased expression of growth factors and ECM molecules, both at protein and transcript levels in GFS patients. A decreased DCN in AH seems striking, and if restored might have a therapeutic role in minimizing postoperative scarring to improve GFS outcome.

Elemental concentrations in Choroid-RPE and retina of human eyes with age-related macular degeneration.

Heavy metals, metallic and toxic elements are reported to play an essential role in the complex multifactorial pathogenesis of age-related macular degeneration (AMD). This study was aimed to measure the concentrations of these elements in choroid-RPE and retina of human donor eyes with and without age-related macular degeneration associated changes. Human cadaver donor eyeballs were obtained from the CU Shah eye bank, Sankara Nethralaya Eye Hospital, India, after removal of the cornea. 39 control and 51 AMD donor eyes were used in this study. Alabama grading was done on the histopathological sections to identify early and late age-related macular degeneration changes. Concentrations of lead, cadmium, chromium, cobalt, nickel, arsenic and selenium were determined in choroid-RPE and retina using Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Further, gene expression of oxidative stress-related genes, Nrf-2, HO-1, GCLC, GCLM, and detoxification related gene GSTpi was performed. The data were analyzed for statistical significance using Graph Pad® Prism 5 software. Donor eyes with early and late AMD had significantly higher levels of lead, cadmium, chromium, arsenic, and nickel in choroid-RPE and retina compared to the control eyes. Selenium was significantly increased in late AMD compared to control. No significant difference was observed in the levels of cobalt between eyes with and without AMD. Decreased transcript levels of oxidative stress-related genes were observed in the choroid-RPE and retinal tissues. Nrf-2 (p < 0.05), HO-1 and GCLC expressions were lowered in the retina of AMD, whereas GCLM and GSTpi expressions were decreased (p < 0.05) with an increase in HO-1 in choroid-RPE of AMD. This study provides evidence that alterations of the heavy metals and toxic elements along with oxidative stress may play a role in the pathogenesis of AMD.

Detection of Proteins Associated with Extracellular Matrix Regulation in the Aqueous Humour of Patients with Primary Glaucoma.

Purpose: The protein composition of aqueous humour (AH) has held significant relevance and remains to be the prime sample in the discovery of biomarkers in glaucoma. The purpose of this study is to analyze the AH protein concentrations in primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) and further examine the proteome changes compared to cataract control. Methods: AH was collected from 90 POAG, 72 PACG, 78 cataracts (controls) in this study. The total protein was quantified using Bradford's assay. Samples were subjected to trypsin digestion followed by liquid chromatography-mass spectrometry (LC-MS) for proteomic studies (n = 3 per group). The extracellular matrix has a major influence on the AH outflow, and the regulator proteins osteopontin (OPN), cathepsin D, and cystatin C detected by mass spectrometry are validated in AH samples by Western blot and turbidimetric immunoassay. Results: We observed a significant increase in protein levels of POAG (p = .0009); interestingly, a similar increase in PACG compared to cataract (p < .0001) and POAG (p = .02). Proteomics analysis identified 184, 190, and 299 proteins in control, POAG and PACG. OPN was increased in POAG (p = .0319) and PACG (p = .0103) compared to control. The precursor form of cathepsin D was increased in POAG and decreased in PACG, though not significant compared to control. Cystatin C was also increased in both POAG (p = .0310) and PACG (p = .0125) compared to control. Conclusion: In this study, we report for the first time that PACG cohort had higher total protein compared to controls. A qualitative comparison of proteomes revealed increased numbers of proteins identified in PACG. We assume that elevated levels of OPN and cystatin C in POAG and PACG along with altered cathepsin levels may contribute to ECM aberration in glaucoma.