Abstract
Purpose :
Eye infections with human adenovirus species D type 37 (HAdV-D37) result in severe, ocular surface inflammation, recognized clinically as epidemic keratoconjunctivitis. Our previous work focused on the role of intracellular signaling and downstream chemokine expression in response to HAdV-D37 infection of human corneal fibroblasts. We now elucidate differential patterns of cytokine expression across a broad range of ocular surface cell types and show a relationship between cytokine expression and intracellular trafficking by the virus.
Methods :
Human ocular surface cells, including epithelial cells, stromal cells, and bone marrow derived cells isolated from peripheral blood, were infected with cesium chloride gradient purified HAdV-D37 (MOI of 5 for 4 hours), empty HAdV-D37 viral capsid, or buffer control (mock infection), and incubated in Brefeldin A (20 µg/ml), followed by intracellular staining with antibodies against IL6, IL1β, CXCL10, TNFα, CXCL8, and CCL2, fixation in 2% paraformaldehyde, and quantification by flow cytometry, with statistical analysis by ANOVA. Intracellular localization of Cy3-labeled HAdV-D37 was studied by the Streptolysin O (SLO) method, in which cells infected for one hour are permeabilized with SLO, and stained with anti-Cy3 antibody.
Results :
Each cell type tested except tert-immortalized, human corneal epithelial cells, showed a significant increase in one or more of the cytokines tested above mock infection levels. In particular, in conventional dendritic cells, all the cytokines were increased by infection except CXCL10; intact virus was a stronger inducer of IL6 and CCL2 than empty capsid. On its own, empty capsid also elicited increased IL6 and CCL2 expression. In contrast, in plasmacytoid dendritic cells, only IL6 expression was increased by infection. At one hour post infection, SLO analysis showed HAdV-D37 in the cytosol of corneal epithelial cells but in the endosomes of other cells tested.
Conclusions :
The absence of cytokine expression by HAdV-D37 infected human corneal epithelial cells is consistent with prior observations. These data further confirm cell type specific cytokine responses upon infection, and suggest that endosomal retention of virus is associated with relatively greater proinflammatory responses by an infected cell.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.