Abstract
Purpose: :
Increased risk for development of AMD has been associated with modifications in genes associated with the complement system (complement factor H, complement factor B, complement component 2 and HTRA1/LOC387715). The purpose of this study was to evaluate the role of complement activation in light-exposed retinas.
Methods: :
Albino rats were dark adapted for 24 hrs prior to light exposure. Control rats (N=3) remained in the dark while experimental rats (N=3 per group) were exposed to blue light (220 fc) for 6 hours. Retinas were examined after 3 hours of light exposure, immediately following the 6-hour light treatment, or 1, 2 and 7 days after a 6-hour photic insult. Immunohistochemical localization of C3 and C1q was determined in paraffin embedded tissue.
Results: :
Pyknotic nuclei in the ONL (>50%) were observed in retinas obtained immediately after a 6-hour blue-light exposure which was followed by thinning of the ONL. C1q expression was not observed in control retinas or light-exposed retinas evaluated immediately following light exposure or 1 to 7 days after light exposure. C3 expression was not observed in retinas evaluated immediately after 3 or 6-hour light exposures but was present in retinas examined 1 to 7 days after light exposure. C3 expression was observed in the RPE, subretinal space and ONL.
Conclusions: :
Blue-light exposure results in activation of the alternative complement pathway (positive C3 expression, negative C1q expression). This model may have utility in evaluating therapeutic agents to treat AMD.
Keywords: radiation damage: light/UV • photoreceptors • retinal pigment epithelium