TGF-β2 Promotes Oxidative Stress in Human Trabecular Meshwork Cells by Selectively Enhancing NADPH Oxidase 4...

Area of Science:

• Ophthalmology
• Cell Biology
• Biochemistry

Background:

• Primary open-angle glaucoma (POAG) pathophysiology involves TGF-β2.
• TGF-β2 remodeling of the trabecular meshwork (TM) extracellular matrix (ECM) impairs aqueous humor outflow and elevates intraocular pressure (IOP).
• Oxidative stress is implicated in TGF-β2 signaling in human TM cells.

Purpose of the Study:

• To determine how oxidative stress facilitates TGF-β2 profibrotic responses in cultured primary human TM cells.
• To investigate the role of NADPH oxidase (Nox) in TGF-β2-induced cellular changes.

Main Methods:

• Primary human TM cells were treated with TGF-β2.
• Changes in mRNA and protein expression of Nox isoforms, CTGF, collagens, and Smad2/3 were quantified.
• Inhibition of Nox with GKT137831 and siRNA against Smad3 were employed.
• Immunocytochemistry and phalloidin staining assessed ECM and actin remodeling.

Main Results:

• TGF-β2 selectively increased endogenous Nox4 mRNA and protein expression in TM cells.
• Smad3 knockdown prevented TGF-β2-induced Nox4 mRNA increase.
• GKT137831 attenuated TGF-β2-induced ROS, CTGF, collagen expression, Smad3 phosphorylation, and actin stress fiber formation.

Conclusions:

• TGF-β2 promotes oxidative stress in TM cells via selective upregulation of NADPH oxidase 4.
• Nox4 induction is a key event in TGF-β2-mediated profibrotic responses and ECM remodeling.
• Targeting Nox4 offers a potential therapeutic strategy for POAG.