ESR 11 vision / project
ESR 11: June 26, 2019; PhD Natural Sciences
Role of different receptors in promoting pathogen and leukocyte migration across the BCSFB in meningitis
Echovirus 30 (E-30) is one of the most frequently isolated pathogens in aseptic meningitis worldwide. To gain access to the central nervous system (CNS), E-30 and immune cells have to cross one of the two main barriers of the CNS, the epithelial blood-cerebrospinal fluid barrier (BCSFB) or the endothelial blood-brain barrier (BBB). In an in vitro model of the BCSFB, it has been shown that E-30 can infect human immortalized brain choroid plexus papilloma (HIBCPP) cells.
In the first part of the project we investigated the migration of different T cell subpopulations, naive and effector T cells, through HIBCPP cells during E-30 infection. Effects of E-30 infection and the migration process were evaluated via immunofluorescence and flow cytometry analysis, as well as transepithelial resistance and dextran flux measurement.
We could demonstrate that Th1 effector cells and enterovirus-specific effector T cells migrated through HIBCPP cells more efficiently than naive CD4+ T cells following E-30 infection of HIBCPP cells. Among the different naive T cell populations, CD8+ T cells crossed the E-30-infected HIBCPP cell layer in a significantly higher number than CD4+ T cells. A large amount of effector T cells also remained attached to the basolateral side of the HIBCPP cells compared with naive T cells. Analysis of HIBCPP barrier function showed significant alteration after E-30 infection and trans- as well as paracellular migration of T cells independent of the respective subpopulation. Morphologic analysis of migrating T cells revealed that a polarized phenotype was induced by the chemokine CXCL12, but reversed to a round phenotype after E-30 infection. Further characterization of migrating Th1 effector cells revealed a downregulation of surface adhesion proteins such as LFA-1 PSGL-1, CD44, and CD49d.
Taken together these results suggest that naive CD8+ and Th1 effector cells are highly efficient to migrate through the BCSFB in an inflammatory environment. The T cell phenotype is modified during the migration process through HIBCPP cells.
In the second part of the project we investigated the polar infection with E-30 of HIBCPP cells. Both, apical and basolateral infections caused a significant decrease of the transepithelial resistance (TEER) of HIBCPP cells in a dose-dependent manner. However, to reach the same TEER decrease the multiplicity of infection (MOI) of the apical infection had to be 20 times higher than the basolateral infection. In line with this finding the number of infected cells at respective time-points after basolateral infection was significantly higher compared to apical infection. Cytotoxic effects of E-30 on HIBCPP cells during basolateral infection were observed following prolonged infection, and appeared more drastically compared to the apical infection. Evaluation of massive analysis of cDNA ends (MACE) RNA data comparing basolateral versus apical infection, revealed a distinct pattern of up- and down-regulated genes depending on the side of infection. Altogether, theses data highlight the polar effect of E-30 in HIBCPP cells as an important factor for an efficient infection.
University Heidelberg, University Children`s Hospital Mannheim, Germany
Tobias Tenenbaum and Horst Schroten
Early Stage Researcher