Date of Award

1-7-2024

Document Type

Thesis

School

School of Chemical & Biotechnology

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr.K.Coral Miriam

Second Advisor

Dr.Nageswara Rao Dunna

Keywords

Glaucoma, POAG, PACG, Aqueous Humor, Human Tenon’s Fibroblast, Glaucoma Filtration Surgery

Abstract

Glaucoma is the second leading cause of blindness with irreversible vision loss. It is marked by the degeneration of retinal ganglion cells, which results in optic nerve head damage. Intraocular pressure (IOP) is a prime risk factor of glaucoma controlled by various treatment regimens i.e., medication, laser, and/ or surgery. It is reported that longterm exposure to anti-glaucoma medications (AGM) may subtle the surgical success rate leading to postoperative fibrosis. Transforming growth factor beta (TGF-β) is a growth factor that plays an important role in the development of glaucoma and promotes fibrosis.

This study is aimed at developing peptides to inhibit TGF-β as a therapeutic strategy. The total protein concentration in the aqueous humour (AH) was found to be substantially higher (p < 0.05) in primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG) patients compared to controls in the current study. Interestingly, mass spectrometry analysis unraveled numerous extracellular matrix

(ECM) proteins in PACG compared to POAG. Further, this study reports significantly increased expression of growth factors and ECM molecules (p < 0.05), both at protein and transcript levels in AH and tenon's tissue in glaucoma filtration surgery (GFS) patients compared to the cataract controls. While remarkably lowered expression of decorin, an anti-fibrotic molecule in AH and tenons of POAG and PACG compared to the control is a striking finding.

This study had shown a significant increase (p < 0.05) in the specific protein of AH i.e., CTGF, TGF-β1, TGF-β2, ELN, SPARC, LOXL2, and a decrease (p < 0.05) in DCN in primary glaucoma patients (i.e., POAG and PACG) with increased duration of preoperative AGMs (> 10 yrs), cup-to-disc ratio (CDR) < 0.5, visual field index (VFI) below 25 %, preoperative IOP > 20 mm of Hg and postoperative bleb with poor surgical

outcome. This study demonstrated a notable ECM alteration with increased SPARC, LOXL2, collagen levels, and a significant decrease in DCN, in human tenon’s fibroblast (HTFs) on exposure to various AGMs ± TGF-β1 co-treated conditions.

This study also revealed that peptides from the leucine rich repeat 5 (LRR5) of small leucine rich proteoglycans (SLRP) derived at 100 μM concentration significantly (p < 0.05) inhibited HTFs migration, downregulated TGF-β1 mediated phosphorylated Smad signaling, decreased collagen synthesis, inhibited collagen gel contraction, and decreased ECM remodeling proteins in TGF-β1 co-treated condition. Collectively, this study is the first report to show increased ECM remodeling proteins and lowered expression of DCN in AH and tenon’s tissue of primary glaucoma patients which is a prominent finding. The present study has provided novel insights on the anti-fibrotic role of SLRP derived peptides in HTFs; thereby it may minimize postoperative fibrosis to improve GFS outcomes which warrant further investigation.

Download

Share

COinS