Abstract
Purpose: :
To investigate whether complement expression is regulated by intraocular pressure in retinal cell cultures in vitro, retinal explant tissue cultures and induced models of glaucoma in vivo.
Methods: :
TR-MUL5 Muller cell line, RGC-5 Retinal Ganglion Cell line cultures and whole mounted C57BL/6 mouse retina tissue cultures were maintained under hydrostatic pressures of 0, 15, 30 or 45mmHg for either 24 or 72 hours. All experiments were repeated 4 times. High intraocular pressure was also unilaterally induced for 8 days via intracameral injection of polystyrene beads in a group of C57BL/6 mice (n=6) while another group (n=3) served as naive control group that no eye received injection. Intraocular pressure was monitored using a rebound tonometer. At the end of the experiment, RNA and protein was extracted from cell cultures, explants and retinas and RT-PCR was performed for C1q, C2, C3, C4, CFI, CFH and CD93. Protein expression of C1q and C3 was examined using immunoblotting and normalized against b-actin expression.
Results: :
RT-PCR experiments for TR-MUL5, RGC-5 cell cultures and retinal explant tissue cultures, showed low levels of expression of the complement genes studied while no significant difference (ANOVA, p>0.05) was observed under any of the conditions of hydrostatic pressure they were subjected to, for either 24 or 72 hours. Similarly, levels of both intracellular and extracellular C1q and C3 protein remained unchanged (p>0.05). C1q and C3 protein in retinas of animals that received microbead injection in the anterior chamber also showed no significant difference (p>0.05) to contralateral uninjected retinas or naïve control animal retinas.
Conclusions: :
The expression of complement components in Muller cell and Retinal Ganglion Cell lines and in retinal explants in culture as well as in the retina in vivo is not influenced by short term rise in hydrostatic pressure. More research is needed to determine the stimulus behind the upregulation of members of the complement system that is observed in glaucoma.
Keywords: intraocular pressure • Muller cells • retinal culture