Retinal pigment epithelium (RPE) builds the outer blood-retinal barrier of the eye. Since one typical feature of the
autoimmune disease, equine recurrent
uveitis (ERU), is the breakdown of this barrier, we recently performed comparative analysis of healthy and uveitic RPE. We identified for the first time
peripherin 2, which is responsible for visual perception and retina development, to be localized in RPE. The purpose of this study was therefore to validate our findings by characterizing the expression patterns of
peripherin 2 in RPE and retina. We also investigated whether
peripherin 2 expression changes in ERU and if it is expressed by the RPE itself. Via immunohistochemistry, significant downregulation of
peripherin 2 in uveitic RPE compared to the control was detectable, but there was no difference in healthy and uveitic retina. A further interesting finding was the clear distinction between
peripherin 2 and the phagocytosis marker,
rhodopsin, in healthy RPE. In conclusion, changes in the expression pattern of
peripherin 2 selectively affect RPE, but not retina, in ERU. Moreover,
peripherin 2 is clearly detectable in healthy RPE due to both phagocytosis and the expression by the RPE cells themselves. Our novel findings are very promising for better understanding the molecular mechanisms taking place on RPE in
uveitis.