Dynasore protects the ocular surface against damaging oxidative stress

Area of Science:

• Ocular surface disease
• Cellular biology
• Pharmacology

Background:

• Water-soluble vital dyes are clinically used to evaluate ocular surface health.
• The precise mechanisms driving vital dye uptake by living cells are not fully understood.
• Previous research suggests sublethal cellular damage may stimulate vital dye uptake.

Purpose of the Study:

• To investigate the cellular mechanisms underlying vital dye uptake in ocular surface health assessment.
• To test the hypothesis that dye uptake occurs via endocytic vesicles following cell damage.
• To explore the potential therapeutic applications of identified mechanisms or compounds.

Main Methods:

• Applied oxidative stress to human corneal epithelial cell cultures (undifferentiated and differentiated models).
• Co-treated cells with vital dyes and endocytosis inhibitors, including Dynasore.
• Utilized ex vivo mouse eye models to assess dye uptake and Dynasore's effect.
• Conducted cytotoxicity and western blotting assays to elucidate Dynasore's mechanism.

Main Results:

• Oxidative stress stimulated dye uptake and endocytosis in undifferentiated cells, blocked by inhibitors.
• In differentiated cells, stress stimulated dye uptake but not endocytosis; only Dynasore blocked uptake.
• Dynasore blocked stress-induced dye uptake in ex vivo mouse eyes when applied concurrently with stress.
• Dynasore demonstrated protective effects on cell and glycocalyx integrity, preventing stress-induced damage and dye entry.

Conclusions:

• Vital dye uptake in differentiated ocular surface cells is not primarily mediated by endocytosis.
• Dynasore acts as a cytoprotective agent, preventing stress-induced damage and subsequent vital dye uptake.
• Dynasore and its analogues show promise as therapeutic agents for ocular surface diseases.