Rabbit retinal Muller cells undergo antigenic changes in response to experimentally induced proliferative vitreoretinopathy

Experimental proliferative vitreoretinopathy (PVR) was induced in the rabbi t eye by injecting mitotically active Muller cells into the vitreal chamber . Two weeks after the initiation of PVR, the retina and the epiretinal memb rane that formed were examined to ascertain the antigenic expression of Mul ler cells in the retina and in the epiretinal membrane. Examination of vari ous regions of the retina from the experimental PVR eye demonstrated that v imentin, glial fibrillary acidic protein (GFAP), cellular retinaldehyde bin ding protein (CRALBP), and beta-amyloid precursor protein (beta-APP), which were present in the Muller cells of the retina from the control eye, incre ased their expression, while the antigenicity of glutamine synthetase (GS), did not change; these proteins were also present in the cells contained wi thin the experimentally induced epiretinal membrane. Alpha smooth muscle ac tin (alpha-SMA), a cytoskeletal protein that is associated with migration a nd tractional forces in many cell types, was not only present in the cells embedded within the epiretinal membrane, but was also present in the Muller cells underlying the epiretinal membrane. However, Muller cells that were in the inferior portion of the retina, where epiretinal membrane pathology was absent, did not express alpha-SMA. Although this protein is not normall y found in Muller cells, they do express it de novo when they are maintaine d in culture. This suggests that a localized mechanism associated with epir etinal membrane formation induces the expression of alpha-SMA in Muller cel ls while the increased expression of GFAP, beta-APP, vimentin, and CRALBP a re probably regulated via a more general mechanism. (C) 1999 Academic Press .