Abstract
Purpose:
To investigate the role of complement factor B (CFB) and complement activation product- membrane attack complex (MAC) in the pathology of glaucoma.
Methods:
Glaucoma was induced by elevating IOP by laser photocoagulation (two treatments, 7 days apart) of episcleral and limbal veins of Lewis rat eyes. The limbal vein and the three episcleral veins were photocoagulated (power 1000 mV; duration, 0.1 s) using an Argon laser. Approximately 80 laser spots around the limbal vein (except the nasal area) and 15 laser spots on each episcleral vein were applied. Intra-ocular pressure (IOP) was measured with a Tonolab tonometer before the first laser treatment and at different time points after the first laser treatment. Levels of CFB, MAC and activated caspase-3 were investigated in retinal ganglion layer of these animals using immunofluorescent (IF) staining. The function of CFB and MAC was blocked using specific antibodies against CFB and C6 respectively. Terminal deoxynucleotidyl transferase (TdT)-mediated d-UTP-biotin nick end labeling (TUNEL) assay was used to detect the apoptotic cells in RGC layer.
Results:
Our results demonstrated that CFB is elevated in the eyes with increased IOP. Our results of IF demonstrated that the inhibition of CFB led to reduced MAC level in the cells present in the RGC layer. TUNEL staining revealed the presence of only few apoptotic cells in RGC layer of anti-CFB antibody-treated rat eyes with elevated IOP. Inhibition of MAC using anti-C6 resulted in low levels of MAC and activated caspase-3 in the RGC layer of laser treated eyes.
Conclusions:
Our results demonstrate that MAC formed as a result of activation of CFB dependent complement alternative pathway plays a major role in the apoptosis of cells present in RGC layer in experimental glaucoma.
Keywords: 531 ganglion cells •
557 inflammation •
555 immunomodulation/immunoregulation