Abstract
Immune responses require spatial and temporal coordinated interactions between different cell types within distinct microenvironments. This dynamic interplay depends on the competency of the involved cells, predominantly leukocytes, to actively migrate to defined sites of cellular encounters in various tissues. Because of their unique capacity to transport antigen from the periphery to secondary lymphoid tissues for the activation of naive T cells, dendritic cells (DCs) play a key role in the initiation and orchestration of adaptive immune responses. Therefore, pathogen-mediated interference with this process is a very effective way of immune evasion. CYTIP (cytohesin-interacting protein) is a key regulator of DC motility. It has previously been described to control LFA-1 deactivation and to regulate DC adherence. CYTIP expression is up-regulated during DC maturation, enabling their transition from the sessile to the motile state. Here, we demonstrate that on infection of human monocyte-derived DCs with herpes simplex virus type 1 (HSV-1), CYTIP is rapidly degraded and as a consequence β-2 integrins, predominantly LFA-1, are activated. Furthermore, we show that the impairment of migration in HSV-1-infected DCs is in part the result of this increased integrin-mediated adhesion. Thus, we propose a new mechanism of pathogen-interference with central aspects of leukocyte biology.