Our Lead Drug Product

Proteris Biotech is developing Protearin™ (rhCLU ophthalmic solution) for the treatment of dry eye.

The active pharmaceutical ingredient is clusterin, a natural glycoprotein found in all bodily fluids. Clusterin is a molecular chaperone and a proteinase inhibitor. It binds directly to the damaged ocular surface to protect, seal, and heal. As shown in experimental models of dry eye, clusterin:

  1. Seals ocular surface damage and prevents further damage

  2. Reduces inflammation

  3. Restores goblet cells that produce the soluble mucins needed for high-quality tears

  4. Regenerates corneal nerves

Conceptual Model of Sealing by Clusterin at the Ocular Surface

Damage to the mucosal glycocalyx and plasma membrane is sealed by clusterin binding to damaged and denatured proteins, and by clusterin intercalation into the lipid bilayer.

Gold “brushes” represent highly glycosylated membrane-associated mucin ectodomains projecting into the tear film. Green “Pacman mouths” represent galectin molecules that link mucin ectodomains, forming a tight barrier that protects the ocular surface epithelial cells. Purple “stubs” represent damaged mucins. Light blue “ball and hairpin” structures represent the lipid bilayer of the epithelial cell plasma membrane. Blue “stools” represent clusterin.

Image created by Ella Marushchenko