Molecular responses of human retinal pigment epithelial cells to ebolavirus VP24.

Purpose: Uveitis (inflammation inside the eye) is a disabling manifestation of the post-Ebola syndrome that affects 10% to 35% of individuals who survive the infection. Post-Ebola uveitis presents with diverse clinical features but frequently involves the posterior segment of the eye, where the retinal pigment epithelium plays a key role in directing immune responses. Our previous work shows that this epithelium is relatively susceptible to infection with Methods: We investigated the activity of EBOV viral protein 24 (VP24) in human retinal pigment epithelial cells. An EBOV VP24 expression plasmid was constructed in-house. Multiple primary cell isolates were lipofectamine-transfected, first with VP24 or control expression plasmids and then with polyinosinic-polycytidylic acid (poly I:C) to simulate viral RNA. A type I interferon (IFN) response to transfection was confirmed by an IFN-β enzyme-linked immunosorbent assay. Cellular immune responses after 4- and 24-h exposures to poly I:C were characterized by reverse transcription-quantitative polymerase chain reaction. Results: Multidimensional scaling, drawing on 19 immune response-related gene transcripts, covering antiviral, immunomodulatory, and proinflammatory molecules, demonstrated changes in gene expression profiles following transfection. Analysis of individual cell isolates showed a range of changes, including upregulation and downregulation of different gene transcripts across the two investigated time points. Conclusions: Our findings suggest VP24 elicits variable immune responses from human retinal pigment epithelial cells, potentially contributing to the variation in clinical presentations of uveitis in Ebola survivors.