Topographic protein profiling of the age-related proteome in the retinal pigment epithelium of Callithrix jacchus with respect to macular degeneration

In the retinal pigment epithelium (RPE) several factors within the macular compared to peripheral regions cause differences in physiological aging. The molecular mechanisms during aging in the context of topography are not well known. The proteome of RPE of different aged macular-bearing primates Callithrix jacchus was thus analysed with ion mobility mass spectrometry. Macular and periphery of neonate RPE were well differentiated from aged tissues as demonstrated by principal component analysis. This finding was mainly due to proteins involved in major developmental processes and the visual cycle. The distinction of adult from senile tissue and macular from periphery was more subtle. The hypotheses of inflammation increasing with age was supported. High expression levels of proteins related to oxidative stress (e.g., cathepsin B) and chaperones (e.g., HSP90) were detected in aged RPE as confirmed by Western blot and immunohistochemical analysis. Decreased levels of proteins participating in angiostatic properties (e.g., thrombospondin 1) and the integrity of tissue basement membranes with age (e.g., nidogen 1) were in agreement with neovascularization. This study presents targets for further investigations of the mechanisms of the aging process with the aim to elucidate predictive factors for the conversion of physiological aging into pathological conditions. Significance: The current study characterized the different protein profiles of the retinal pigment epithelium (RPE) of the macula-bearing, non-human primate Callithrix jacchus during life-time. In addition, the sub-proteomes of macular and peripheral RPE were investigated. Differently expressed proteins described developmental processes in neonate tissue and destructive mechanisms in aged samples. Insights into the physiological aging process of the RPE and its conversion into pathophysiological conditions were gained. They assist in designing therapeutical approaches to counteract age-related diseases of the retina.