Listeria monocytogenesInfection and Activation of Human Brain Microvascular Endothelial Cells

Listeria monocytogenes invasion of human brain microvascular endothelial cells (BMEC) and its role as a stimulus for endothelial cell activation were studied. Binding and invasion of intact BMEC monolayers were independent of the L. monocytogenes inlAB invasion locus. Cytochalasin D abrogated invasion of BMEC, whereas genistein effected only a 53% decrease in invasion, indicating a requirement for rearrangement of actin microfilaments but less dependence on tyrosine kinase activity. L. monocytogenes stimulated surface expression of E-selectin, ICAM-1, and to a lesser extent, VCAM-1, whereas L. monocytogenes prfA- and Deltahly mutants were severely compromised in this respect. Other experiments showed that BMEC infection stimulated monocyte and neutrophil adhesion and that CD18-mediated binding was the predominant mechanism for neutrophil adhesion to infected BMEC under static conditions. These data suggest that invasion of BMEC is a mechanism for triggering inflammation and leukocyte recruitment into the central nervous system during bacterial meningitis.