Abstract
Purpose:
Latest studies assume a participation of the complement system (CS) in the development of glaucoma. However, less is known about the pathways which activated the CS. In this study we wanted to investigate which complement pathways may play a role in the activation of the CS in an autoimmune model of glaucoma.
Methods:
Rats were immunized with optic nerve homogenate (ONA) or S100 protein. The control group (Co) received sodium chloride. After 7 and 14 days cross-sections of the retina were stained with C1q (Quidel), mannose binding lectin (MBL; Biozol), and mannose-associated-serine-proteases 2 (MASP2; Biozol) (n=5-6/group). Complement components were counted using ImageJ Software. Statistical analysis was performed using t-test.
Results:
7 days after immunization, no difference could be observed in C1q staining in both immunized groups compared to Co (ONA: p=0.09; S100: p=0.7). Regarding MBL, less cells could be seen in the ONA group compared to Co (p=0.0005), no changes could be noted in the S100 group (p=0.8). Although mean values showed no difference, we noted distinct more C1q and/or MBL positive cells in single immunized eyes compared to Co. Regarding MASP2 staining, significant more positive area could be seen in the ONA group compared to Co (Co: 4.24%±5.03; ONA: 9.45%±7.22; p=0.000001). No difference was noted in the S100 group (p=0.4). 14 days after immunization, no changes in C1q or MBL staining could be observed in the ONA animals (C1q: p=0.8; MBL: 0.5). Less C1q and MBL was present in the S100 group (C1q: p=0.002; MBL: p=0.046). At this point in time MASP+ area significantly decreased in ONA group (p=0.000001). No changes could be observed in the S100 group compared to Co (p=0.4).
Conclusions:
C1q and MBL, the marker for classical pathway or lectin pathway, were not significantly increased in both immunized groups at both points in time. But we could detect more MASP2 activation in ONA animals after 7 days. Nevertheless, we noted in single immunized eyes significant more C1q and/or MBL depositions compared to Co. Additionally, in previous studies, we could show a significant increase of C3 and the terminal pathway of the CS. These data suggest, that the CS might be activated via the classical and lectin pathway at an earlier point in time in this model.
Keywords: 688 retina •
554 immunohistochemistry •
555 immunomodulation/immunoregulation