Abstract
Introduction: :
The retinal damage induced by laser photocoagulation is multiplied by secondary degeneration processes whereby tissues adjacent to the primary lesion are destroyed. The neuroprotective effect of immunization by the peptide glatiramer acetate (Copolymer–1) on the retina against laser–induced damage was previously reported (Belokopytov M, et al. IOVS 2004Abstract 837). PN–277 is a newly developed peptide similar to CNS antigens. It activates the immune system causing it to recognize the lesion site, and probably activates the resident cells to eliminate compounds involved in secondary degeneration and secrete factors that induce axonal elongation, synaptogenesis and neurogenesis.
Purpose: :
To test the neuroprotective ability of PN–277 to reduce the spread of laser–induced retinal damage.
Methods: :
Standard argon laser lesions (514 & 544 nm, 200 mm, 0.1 W, 0.05 second) were created in 36 DA pigmented rats pretreated by PN–277 (500 µg subcutaneously) or saline seven days before the laser session. The lesions were evaluated histologically and morphometrically 3, 20 and 60 days after the injury.
Results: :
The administration of PN–277 reduced the cell loss in the center of lesion area (P < 0.01) and decreased the laser lesion diameter (P < 0.01) sixty days after injury.
Conclusions: :
The results show that early pre–immunization with PN–277 is neuroprotective in unmyelinated (gray matter) neural tissue such as the retina. The clinical utility of this approach should be tested functionally. If successful, PN–227 may be tested clinically for prevention and treatment of various ophthalmic degenerative diseases and prophylaxis against laser–induced retinal injuries.
Keywords: immunomodulation/immunoregulation • neuroprotection • laser