High Intraocular Concentration of Fibrinogen Regulates Retinal Function Via the ICAM-1 Pathway.

Purpose: Diabetic retinopathy (DR) is a significant complication of diabetes mellitus that can lead to progressive visual impairment. This study aimed to elucidate the role of fibrinogen, a protein whose serum and intraocular concentrations are elevated in patients with diabetes and DR, in the pathogenesis of DR.
Methods: The changes in the protein levels of the neuronal marker tubulin-β3 (TUBB3) and retinal response induced by the intravitreal injections of 1× phosphate-buffered saline, 40 mg/mL of fibrinogen, and 40 mg/mL of fibrinogen in combination with anti-intracellular adhesion molecule-1 (ICAM-1) antibody in normal mice were observed using immunofluorescence, western blotting, and electroretinography.
Results: High concentrations of fibrinogen led to a decrease in the expression of TUBB3 in immunofluorescence and western blotting. The amplitudes of the positive scotopic threshold response and b-wave were notably reduced after the injection of fibrinogen, indicating potential damage to the retinal ganglion cells. The co-administration of anti-ICAM-1 antibody effectively mitigated these fibrinogen-induced changes, indicating that fibrinogen-induced damage is mediated via the ICAM-1 pathway.
Conclusions: The present study underscores the significance of elevated intraocular fibrinogen levels as a pathogenic factor in DR. Involvement of the fibrinogen/ICAM-1 pathway presents new avenues for therapeutic intervention, especially in patients with treatment-resistant conditions.