DESCRIPTION (provided by applicant): Bacterial meningitis continues to be an important cause of mortality and morbidity. A major contributing factor to such mortality and morbidity is our incomplete knowledge on the pathogenesis of this disease. E. coli is the most common Gram-negative bacillary organism causing meningitis, but the pathogenesis of E. coli meningitis remains incompletely understood. Several lines of evidence from human cases and experimental animal models of E. coli meningitis indicate that E. coli penetration into the brain follows a high level of bacteremia and cerebral capillaries are the portal of entry into the brain.
Since E. coli penetration into the brain occurred in the cerebral microvasculature, we developed the blood-brain barrier model with human brain microvascular endothelial cells (HBMEC) to study E. coli penetration of the blood-brain barrier. Our HBMEC monolayer, upon cultivation on collagen-coated Transwells, exhibits spatial organization of tight and adherens junction proteins as well as a polarized monolayer, a unique property of the blood-brain barrier endothelial cells. We have shown for the first time that meningitis-causing E. coli strains exhibit the ability to invade the HBMEC monolayer in vitro and that the ability of HBMEC invasion is correlated with E. coli penetration into the brain in vivo. The mechanisms involved in E. coli penetration of the blood-brain barrier, however, remain incompletely understood. Our preliminary studies revealed a novel mechanism exploited by meningitis-causing E. coli for invasion of the blood-brain barrier, and also suggest that such mechanism is likely to contribute to another meningitis-causing pathogen for penetration of the blood-brain barrier. Determination and characterization of such new mechanism will, therefore, provide a paradigm-shifting strategy for elucidating the pathogenesis of bacterial meningitis.