Inhibitory effects of PPARγ ligands on TGF-β1-induced corneal myofibroblast transformation

Area of Science:

• Ophthalmology
• Cell Biology
• Pharmacology

Background:

• Corneal scarring from injury, surgery, or infection is a major cause of vision loss.
• Ligands for peroxisome proliferator-activated receptor gamma (PPARγ) have demonstrated anti-scarring properties in various tissues.
• The efficacy and mechanisms of PPARγ ligands in corneal scarring are not well understood.

Purpose of the Study:

• To investigate the anti-fibrotic effects of three PPARγ ligands in cat corneal fibroblasts.
• To elucidate the signaling pathways involved in the anti-scarring mechanisms of these ligands.
• To evaluate the in vivo efficacy of troglitazone in a preclinical model of corneal injury.

Main Methods:

• Western blot analysis to assess protein expression and phosphorylation.
• Treatment of cat corneal fibroblasts with PPARγ ligands and transforming growth factor (TGF)-β1.
• Assessment of corneal haze and α-smooth muscle actin expression in a cat photorefractive keratectomy model.

Main Results:

• All three PPARγ ligands (15-deoxy-Δ12,14-prostaglandin J2, troglitazone, rosiglitazone) reduced TGF-β1-induced myofibroblast differentiation and extracellular matrix deposition.
• These anti-fibrotic effects were independent of PPARγ activation but significantly inhibited p38 mitogen-activated protein kinase phosphorylation.
• Topical troglitazone application reduced corneal haze and α-smooth muscle actin expression in vivo.

Conclusions:

• PPARγ ligands exhibit significant anti-fibrotic potential in corneal fibroblasts through p38 MAPK signaling.
• Troglitazone demonstrates therapeutic promise for preventing or reducing corneal scarring.
• Further research into PPARγ ligand mechanisms could lead to novel anti-scarring therapies for the eye.