Abstract
Purpose: :
Retinal injuries affecting the retinal pigment epithelium may result in leakage of retinal proteins into the systemic circulation through the underlying choroid. We hypothesize that autoantibodies against these proteins are generated following retinal laser photocoagulation.
Methods: :
Using a continuous 532 nm laser, 50 laser spots of mild, minimally visible lesion (MVL, n=10), moderate (grade II, n=8), or severe (grade III, n=6) lesions were created in retinas of Dutch Belted rabbits. Twelve weeks following treatment, serum was collected from treated and control rabbits. Serum immunoreactivity to retinal proteins was determined using two dimensional electrophoresis followed by western blot (WB). Proteins reactive only in blots that used laser-treated sera as primary antibody were excised from the gel and identified by liquid chromatography/tandem mass spectrometry. Pathway Studio 6.0TM was used to map the proteins into functional categories.
Results: :
Fifteen autoantibodies were detected in the serum of laser treated rabbits. The autoantigens were identified as alpha-enolase, fructose-bisphosphate aldolase C, T-complex protein-1-zeta, transketolase, glutamine synthetase, pyruvate kinase isozyme, elongation factor 1, vasolin-containing protein, transferrin, dihydropyrimidinase related protein-2, beta-2-tubulin, ubiquilin-1, cofilin-1, triosephosphate isomerase and DEAD box protein 17. Seven, eleven, and one protein were detected following MVL, grade II, and grade III laser treatment respectively; 4 were common to both MVL and grade II. Most proteins are expressed in the retina as confirmed by immunohistochemistry and WB. Per the t-test provided by the Pathway Studio 6.0TM, the functional groups significantly represented by these proteins included inflammation and apoptosis.
Conclusions: :
Detection of autoantibodies against retinal proteins in serum of laser treated rabbits demonstrates that an immune response is elicited following retinal laser injury. The autoantibody response appears to be related to proteins expressed in the retina but not to retina specific proteins. The response was more robust with MVL and grade II laser lesions, suggesting that the more severe grade III lesions cause protein degradation at the site of injury and does not initiate an immune response.
Keywords: retina • laser • proteomics